bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of neural crest ablation on development of the heart and arch arteries in the chick
Authors: Bookman Dale E. , Redmond Mary E. , Waldo Karen , Davis Harry , Kirby Margaret L.
Published: February 2005

Mesenchymal derivatives of the neural crest contribute to the connective tissues and blood vessels of the pharyngeal arches, and participate in the septation of the outflow tract of the heart. The present study was designed to determine the nature and timing of alterations in the development of the heart and arch arteries subsequent to diminished neural crest contributions. The neural crest contributing to the three caudalmost pharyngeal arches was ablated bilaterally in chick embryos and compared with sham or unoper‐ated controls. Heart development was studied by scanning electron microscopy. Arch artery development was studied microscopically after intravascular injection of India ink and clearing of the specimen. Neural crest ablation caused morphological changes in most hearts. Hearts in experimental animals commonly were elongate and were subject to inappropriate development of ventricular and atrial areas. A surgical effect delayed the disappearance of arch arteries one and two, and removal of neural crest produced an additional delay. Neural crest ablation caused failure of arch arteries three, four (right), and six to develop to the proper size in some animals. Survival of those whose sixth arch arteries achieved the proper size caused group measurements to reach normal values again by stage 32. Closure of arch arteries in some animals and maintenance in others produced greater variability in experimental animals than in controls. It is significant that heart morphology was altered before septation of the outflow tract normally occurs. This indicates at the least that another factor, such as altered blood flow, contributes to the abnormal development. Altered flow may result from changes in pharyngeal arch mesenchyme and arch artery endothelium.
Distribution of serotonin‐immunoreactive paraneurons in the lower urinary tract of dogs
Authors: Hanyu Shugo , Iwanaga Toshihiko , Kano Kenichi , Fujita Tsuneo
Published: February 2005

Morphological and quantitative studies were made on serotonin‐containing paraneurons throughout the lower urinary tract in male and female dogs. Using an anti‐serotonin antiserum, the cells were consistently demonstrated to be dispersed in the epithelium from the vesico‐urethral junction to the external urethral ostium. They occurred most frequently in the urethra proximal to the urogenital diaphragm in both sexes. The total number of the serotonin‐immunoreactive cells in the urethra, was estimated to be 36.2 × 104 (SD 9.9 × 104 in the male (n=3) and 15.6 × 104 2.1 × 104) in the female (n=3). Besides the urethra, the prostate and vaginal vestibule contained several sero‐tonin‐immunoreactive cells. The urethral serotonin cells were basically bipolar basal‐granulated cells that extended the basal cytoplasm too the basement membrane and reached the lumen with an apical process. Modified cell shapes were, however, also frequent, and included bifurcated apical and/or basal processes or a laterally directed basal process. Occasional serotonin cells possessed a threadlike basal process with varicos‐ities and a terminal bouton, reminiscent of a neuronal process. Immunoreactivity for chromogranin A, a carrier protein common to endocrine paraneurons, was demonstrated in all of the urethral serotonin cells. The chromogranin A‐immunoreactive granules accumulated more densely in the basal and perinuclear regions of the cell. It is hypothesized that the serotonin‐immu‐nopositive paraneurons may receive chemical and/or physical information from urine and, in response to it, secrete serotonin which presumably causes the contraction of the musculature of the urethra.
An assessment of posture in bipedal rats
Authors: Moravec Steven J. , Cleall John F.
Published: February 2005

Alteration in posture was examined following foreleg amputation in rats. After the surgical induction of bipedal stance, a detailed, quantified, and longitudinal assessment of rat posture and the amount of time spent in the upright stance was undertaken.

An experimental group of rats had both forelimbs amputated. A group of unaltered quadrupedal rats served as controls. A standardized series of photographs of altered and control rats was taken. Postural differences between the two groups of rats were analyzed through photographic analysis of their profiles in upright and in crouched positions.

Analysis of the photographs showed that the percentage of rats assuming upright posture did not differ between the experimental and control groups. Foreleg amputation forced the rats to adopt an altered posture, but did not result in habitual assumption of upright stance to a greater degree than that of controls. Adaptation to bipedalism was marked by a tucking of the hindlimbs under the body, and a flexure of the vertebral column and the head.
Animal model of acute pericarditis and its progression to pericardial fibrosis and adhesions: Ultrastructural studies
Authors: Leak Lee V. , Ferrans Victor J. , Cohen Steven R. , Eidbo Elling E. , Jones Michael
Published: February 2005

To study the evolution of pericardial inflammation, we have developed a model of pericarditis in sheep by surgically injecting heat‐killed staphy‐lococci and Freund's adjuvant into the pericardial cavity under sterile conditions. The pericarditis evolved through the following phases: (1) inflammatory response, (2) mesothelial cell injury and desquamation, and (3) fibrotic phase. At 3–24 hr there was increased microvascular permeability, which resulted in the exudation of fluid, neutrophils, macrophages, ami fibrin into the pericardial cavity and the pericardial intersti‐tium. By 72 hr, large numbers of inflammatory cells were aggregated on the mesothelial surfaces and dispersed throughout the pericardial cavity, either as free‐floating cells or located between strands of fibrin. At 6 days, fibrinolysis was apparent along the mesothelial surfaces; and newly formed collagen fibrils were deposited throughout the interstitial spaces and among the aggregated cells. These fibrils provided a matrix for the growth of new blood and lymphatic vessels into new connective tissue on both parietal and visceral pericardial surfaces. At 2 weeks, intrapericardial fibrosis had produced focal adhesions between the pericardial surfaces. By 1 month, extensive areas of the pericardial cavity were obliterated. By 9 months, there was a marked reduction in the numbers of cells and blood vessels and increased deposition of collagen and elastic fibers. The intrapericardial injection of heat‐killed staphylococci and adjuvant provides a reproducible animal model to study the time course of pericardial inflammation.
On the origin of ganoine: Histological and ultrastructural data on the experimental regeneration of the scales of Calamolchthys calabaricus (osteichthyes, brachyopterygii, polypteridae)
Authors: Sire Y. , Géraudie J. , Meunter F. J. , Zylberberg L.
Published: February 2005

In order to understand the process of anoine formation on the ganoid scales, scale regener‐ation has been studied to overcome the lack of a growth cries of scale ontogeny. Seven stages of ganoid scale regeneration have been defined over a period of five months in the polypterid fish Calamoichthys calabariits. The study has been carried out using transmission electron microscopic techniques. After wound healing and differentiation of the osseous basal plate, a layer of vascular dentin is deposited at the upper surface of he basal plate owing to the presence there of odonto‐ilasts closely applied to the dentin. When these cells nove away, a close contact is then established between he stratified epidermis and the regenerating scale. Nu‐nerous alterations of the epidermal‐dermal boundary occur until its disappearance and a thick layer of pre‐canoine is formed. This layer is progressively mineral‐zed; and finally an organic intermediate layer differentiates between the ganoine, which is a hyper‐nineralized tissue, and the overlying epidermis.

This ultrastructural study demonstrates rather un‐quivocally the involvement of the inner epidermal layer (EL) in the appearance and growth of the ganoine. It suggested that these epidennal cells can be compared functionally to the inner dental epithelium (IDE) described during mammal tooth morphogenesis. Consequently, our results allow us to propose that ganoine an be identified as true enamel, although additional lata are necessary to analyze the proteinaceous com‐ponent of its organic matrix.
Spontaneous regeneration of older dystrophic muscle does not reflect its regenerative capacity
Authors: Bourke Dianna L. , Ontell Marcia , Taylor Floyd
Published: February 2005

Young dystrophic (dy) murine muscle is capable of ( spontaneous) regeneration (i.e., regeneration in the absence of external trauma); however, by the time the mice are 8 weeks old, this regeneration ceases. It has been suggested that the cessation of regeneration in dystrophic muscle may be due to exhaustion of the mitotic capability of myosatellite cells during the early stages of the disease. To test this hyptothesis, orthotopic transplantation of bupivacaine treated, whole extensor digitorum longus muscles has been performed on 14 to 16‐week‐old 129 ReJ/++ and 129 ReJ/dydy mice. The grafted dystrophic muscle is able to produce and maintain for 100 days post‐transplantation 356 ± 22 myofibers, a number similar to that found in age‐matched dystrophic muscle. The ability of old dystrophic muscle to regenerate subsequent to extreme trauma indicates that the cessation of ( spontaneous) regeneration is due to factor(s) other than the exhaustion of mitotic capability of myosatellite cells. Moreover, there is no significant difference in myosatellite cell frequencies between grafted normal and dystrophic muscles (100 days post‐transplantation). Myosatellite cell frequencies in grafted muscles are similar to those in age‐matched, untraumatized muscles. While grafting of young dystrophic muscle modifies the phenotypic expression of histopathological changes usually associated with murine dystrophy, grafts of older dystrophic muscle show extensive connective‐tissue infiltration and significantly fewer myofibers than do grafts of age‐matched normal muscle. As early as 14 days post‐transplantation, it is possible to distinguish between grafts of old, normal and dystrophic muscles. It is suggested that the connective tissue stroma, present in the dystrophic muscle at the time of transplantation, may survive the grafting procedure.
Comparison of components of the testis interstitium with testosterone secretion in hamster, rat, and guinea pig testes perfused in vitro
Authors: Mendis‐Handagama S. M. L. C. , Zirkin B. R. , Ewing L. L.
Published: February 2005

Components of the testis and cytoplasmic organelles in Leydig cells were quantified with morphometric techniques in hamster, rat, and guinea pig. Testosterone secretory capacity per gram of testis and per Leydig cell in response to luteinizing hormone (LH) (100 ng/ml) stimulation was determined in these three species from testes perfused in vitro. Numerous correlations were measured among structures, and between structures and testosterone secretion, to provide structural evidence of intratesticular control of Leydig cell function.

Testosterone secretion per gm testis and per Leydig cell was significantly different in the three species: highest in the guinea pig, intermediate in the rat, and lowest in the hamster. The volume of seminiferous tubules per gm testis was negatively correlated, and the volumes of interstitium. Leydig cell, and lymphatic space per gm testis were positively correlated with testosterone secretion. No correlations were observed between volumes of blood vessels, elongated spindle‐shaped cells, or macrophages per gm testes and testosterone secretion.

The average volume of a Leydig cell and the volume and surface area of smooth endoplasmic reticulum (SER) and peroxisomes per Leydig cell were positively correlated, and the volume of lysosomes and surface area of inner mitochondrial membrane per Leydig cell were negatively correlated with testosterone secretion. No correlations were observed between volume and surface area of rough endoplasmic reticulum (RER), Golgi apparatus, and lipid, and volume of ribosomes, cytoplasmic matrix, and the nucleus with testosterone secretion per Leydig cell.

These results suggest that Leydig cell size is more important than number of Leydig cells in explaining the difference in testosterone‐secreting capacity among the three species, and that this increase in average volume of Leydig cell is associated specifically with increased volume and surface are of SER and peroxisomes. An important unresolved question is what is the role of peroxisomes in Leydig cell steroidogenesis.
Amianthoid (Asbestoid) transformation: Electron microscopical studies on aging human costal cartilage
Authors: Mallinger R. , Stockinger L.
Published: February 2005

The present study reports on the fine structure of human costal cartilage at different ages in order to obtain information on the morphogenesis of amianthoid fibers. Our results reveal an overall increase of collagen fibril diameter with increasing age, even in areas with no signs of amianthoid transformation. Ultrastmctural evidence is presented that this increase in diameter is due to a gathering of the preexisting collagen fibrils. The age‐related change in collagen fibril diameter is paralleled by changes in the composition and ultrastructural appearance of cartilage proteoglycans (as revealed by acridine orange staining). Acridine‐orange‐positive filaments indicative for proteoglycans are markedly reduced in size with advancing age in centrally located regions of costal cartilage. Treatment with testicular hyaluronidase previous to acridine‐orange staining leaves these small proteoglycan filaments unaffected. By contrast, the filaments visible after acridine‐orange staining in the extracellular matrix near to the perichondrium are susceptible to hyaluronidase treatment. Infrequently, a sharp increase in collagen fibril diameter can be observed in territorial matrix areas of degenerating chondrocytes. This observation is conspicuous at ages of 10 and 20 years. Amianthoid transformation is characterized by the appearance of collagen fibrils strictly arranged in parallel. These amianthoid fibers are embedded in a matrix rich in small acridine‐orange‐positive filaments similar to the proteoglycan filaments observed in centrally located matrix regions. It can be concluded that extensive remodelling not only of the collagen fibrils but also of the cartilage proteoglycans is involved in the development of amianthoid transformation.
Developmental heterogeneity of mesenchymal glycosaminoglycans (GAG) distribution in chick embryo lung anlagen
Authors: Becchetti E. , Evangelisti Rita , Stabellini G. , Pagliarini A. , Borrello Elia Del , Calastrini Carla , Carinci P.
Published: February 2005

The presence and distribution of mesenchymal components in the extracellular matrix during lung development in the chick embryo (from 5½/6 to 18 incubation days) has been examined histochemically. Attention is focused mainly on glycosaminoglycans (GAG). Morphological reconstructions show three main stages: first (5½/6–8 days), formation of 2nd‐order branching; second (9–12 days), proliferation of para‐bronchi and third (from 13th day on), formation of air capillaries. In the first phase, hyaluronic acid (HA) prevails around the mesobronchus, but chondroitin sulfate (CS) dominates the 2nd‐order branches. Basement membranes of 2nd‐order branches are strongly positive for sulphated GAG. In the second phase, CSA increases in the ground substance of mesenchyme. This increase is irregular, being smaller in older areas (mesobronchus, branches of 2nd order) and larger in the more recent parabronchi, which extend into the lateral and dorsal areas of the rudiment. An increase in both sulfated GAG and glycoprotein (GP) occurs in basement membranes. In the third phase, GAGs are uniformly distributed in the mesenchymal septa and around the interlobular vascular network. This concentration decreases while the GP concentration increases. Basement membranes around every branch of the 1st, 2nd, and 3rd orders possess large quantities of GP. Mesenchymal GAG occurs in every stage of lung development, temporally correlating with the morphogenesis and differentiation of epithelium. Our results provide necessary information, which has not been available so far. Experimental studies specifically designed to clarify the developmental significance of such a heterogeneous distribution may be interpreted in the light of this information.
Maturation antigen of the mouse sperm flagellum. I. Analysis of its secretion, association with sperm, and function
Authors: Feuchter F. A. , Tabet A. J. , Green M. F.
Published: February 2005

We report here recent findings on the sperm maturation antigen SMA4, which is secreted by holocrine cells of the distal caput epididymis and binds to the flagellar surface of mouse sperm during epididymal transit.

Washed sperm from the caput and corpus epididymides of mice were examined by immunofluorescence and SDS‐PAGE using wheat germ agglutinin, which binds specifically to SMA4 as a primary probe. Results indicate that sperm first exhibit WGA reactivity on their flagellae in the region of the distal caput, and that the appearance of WGA receptors is due to the binding of a 54‐Kd glycoprotein (SMA4) to the cell surface. Extracts of epididymis containing SMA4 were tested for their ability to bind to the surfaces of caput and corpus sperm. Caput sperm surfaces bound SMA4 in & temperature‐independent manner, and binding occurred in the presence of enzyme inhibitors., suggesting a nonenzymatic process. Biochemical studies revealed that SMA4 contains disulfide bonds which stabilize it on the sperm surface and restrict its mobility. Terminal carbohydrate residues of the molecule are sialic acids. The addition of SMA4 to caput sperm flagellae prevented tail‐to‐tail agglutination, normally seen when caput sperm are diluted into saline; and SMA4 was able to disperse clumps of agglutinated caput sperm. The data suggest that a primary function of SMA4 is to prevent tail‐to‐tail agglutination of sperm during storage in the epididymis.
The development of the sexually indifferent gonad in the prosimian, Galago crassicaudatus crassicaudatus
Authors: Yoshinaga Kazuya , Hess David L. , Hendrickx Andrew G. , Zamboni Luciano
Published: February 2005

The morphogenesis of the sexually indifferent gonad of the primate Galago crassicaudatus crassicaudatus was studied by high‐resolution light microscopy and electron microscopy in 15 embryos aged 26 to 33 days. Onset of gonadal development follows the morphogenesis of the mesonephros by a conspicuous interval and is identified as the time when the first primordial germinal cells arrive in the region ventral to the central third of the mesonephros; this is followed by intense proliferation of the coelomic mesothelial cells lining the area. They become organized into short piles that deepen in the underlying mesenchyme, enclosing the germinal cells in the process. Rapidly, the piles become confluent forming a compact mass, the gonadal blastema, which is soon cleaved into gonadal cords by stroma and vascular lacunae. The mesonephros becomes involved in the morphogenesis of the gonad only in late stages of development when anatomic continuities become established between the capsules of its regressing glomeruli and the elongating gonadal rete cords. These observations show that in the Galago the somatic cells of the gonadal blastema, i.e., the precursors of the definitive testicular and ovarian sustentacular cells, derive from the coelomic mesothelium in contrast to other mammals, e.g., ruminants and rodents, where they are of mesonephric derivation. This important point is discussed in light of the differences that exist among species with regard to the structural complexity, functionality, and stages of differentiation/ involution of their mesonephroi on the one hand, and the time of gonadal development on the other.
Ultrastructural cytochemistry of complex carbohydrates in developing feline neutrophils
Authors: Fittschen C. , Parmley R. T. , Austin R. L.
Published: February 2005

The feline species provides animal models for at least six congenital lysosomal disorders. Since knowledge of normal feline neutrophils is a prerequisite for studies of their abnormalities, the present report describes the morphology and cytochemistry of normal feline neutrophils and compares the subcellular distribution of sulfate‐ and vicinal‐glycol‐containing complex carbohydrates to that of peroxidase and acid phosphatase. Immature feline primary granules, formed in promyelocytes, were stained for peroxidase, acid phosphatase, sulfate, and vicinal glycols. During maturation, primary granules retained strong staining for peroxidase, but staining for vicinal glycols decreased, and acid phosphatase and sulfate reactivity was lost. Secondary granules formed in myelocytes lacked peroxidase, acid phosphatase, and sulfate staining, but stained intensely for vicinal‐glycol‐containing complex carbohydrates. No analogues of tertiary granules previously described in rabbits and humans were demonstrated in feline neutrophils. However, a new sequential staining technique for peroxidase and vicinal glycols has suggested the formation in myelocytes and late neutrophils of a third granule type that contained peroxidase, acid phosphatase, and vicinal glycols but lacked sulfate staining. Thus, the staining characteristics of primary and secondary granules in cats closely resembled those in humans and rabbits. The third (late‐forming) type of granule has not previously been described in other species.
Ultrastructure of the pineal body of the common vampire bat, Desmodus rotundus
Authors: Bhatnagar Kunwar P.
Published: February 2005

The type AB pineal body of the common vampire bat, Desmodus rotundus was recessed and lobulated, was extensively vascularized and intimately related to great veins, and was unassociated with the epithalamic region. The habenular and the posterior commmissures coursed anteriorly and were unassociated with the pineal. The saccular suprapineal recess of the third ventricle extended dorsally juxtaposed to the pineal body. These anatomical features are likely to make pinealectomies in the vampire more difficult to manage.

The pineal parenchyma consisted of light pinealocytes surrounded by canaliculi of various sizes, often transmitting unmyelinated nerve fibers and glial processes. Desmosomes were common. The pinealocyte nuclei were large and highly infolded; characteristic cytoplasmic constituents included abundant dilated Golgi complexes associated with clear vesicles, numerous polyribosomes, few single cisternae of ribosome‐studded rough endoplasmic reticulum, mitochondria, and occasional multivesicular bodies and lysosomes. Almost all pinealocytes exhibited centrioles and some, in addition, displayed basal bodies but rarely ciliary shafts. A conspicuous feature of the pinealocyte cytoplasm was the presence of branched bundles of intermediate filaments, especially in the perinuclear zone.

Siderotic macrophages, lipofuscin‐pigment‐containing phagocytic cells, mast cells, myelin bodies, and both fenestrated and continuous capillaries were present. The perivascular compartment was densely packed with unmyelinated nerve bundles containing small to large fibers exhibiting axoaxonic densities. Other constituents of the perivascular compartment were club‐shaped pinealocyte processes filled with clear vesicles, microtubules, an occasional mitochondrion, glial processes, and collagen fibers. “Synapselike” contacts were observed between the axons and pinealocyte processes. Abundant pinocytotic vesicles in the capillary endothelium indicated active pinocytosis. Myelinated nerve fibers were lacking. The pineal ultrastructure of Desmodus is in part unlike that reported for other mammals, including bats.
Gross and cellular analysis of 6‐mercaptopurine‐induced cleft palate in hamster
Authors: Burdett David N. , Shah Ravindra M.
Published: February 2005

The present study analyzes the morphological, histochemical, and ultrastructural aspects of the pathogenesis of 6‐mercaptopurine (6MP)‐induced cleft palate in hamster fetuses. Gross and light microscopic observations indicated that 6MP stunts the growth of vertical palatal shelves and thus induces cleft palate. Ultrastructural analysis showed that, in contrast to controls, 6MP‐induced alterations were first seen in the mesenchymal cells 24 hr after drug administration. The initial alterations were characterized by swelling of the nuclear membrane. During the next 12 hr, lysosomes were seen first in the mesenchymal cells and then in the cells of the medial edge epithelium (MEE) of the developing palatal primordia. The appearance of lysosomes was temporally abnormal and was interpreted as a sublethal response to 6MP treatment. Subsequently, the nuclear alterations and the lysosomes diminished; and 48 hr after 6MP administration, they were absent from the palatal tissues. Ninety hours after 6MP administration, unlike the controls (in which the palatal shelves were already fused), changes were seen at the epithelial‐mesenchymal interface in the developing cleft palatal shelves. These changes were characterized by breakdown of the basal lamina and epithelial‐mesenchymal contacts. Eventually, at term, the MEE of the vertical shelf stratified. It was suggested that 6MP affected cytodifferentiation in the palatal tissues during the critical phase of early vertical shelf development and thereby induced cleft palate.
Nascent muscle fiber appearance in overloaded chicken slow‐tonic muscle
Authors: Kennedy J. M. , Eisenberg B. R. , Reid S. K. , Sweeney L. J. , Zak R.
Published: February 2005

The application of a weight overload to the humerus of chickens induces a hypertrophy of anterior latissimus dorsi (ALD) muscle fibers. This growth is accompanied by a rapid and almost complete replacement of one slow‐tonic myosin isoform, SM‐1, by another slow‐tonic isoform, SM‐2. In addition, a population of small fibers appears mainly in extrafascicular spaces and, concurrently, three additional myosin bands are detected by gel electrophoresis. Five antibodies against myosin heavy chain (MHC) isoforms were selected as immunocytochemical probes to determine the cellular location and nature of these myosins. The antibodies react with ventricular, fast skeletal muscle and either SM‐1 or SM‐2, or both the slow‐tonic MHCs. The antifast and antiventricular antibodies react with myosin present in the 10‐day embryonic ALD muscle but do not react with myosin in posthatch ALD muscle. The small fibers in overloaded muscle contain a myosin isoform characteristically expressed during the embryonic stage of ALD muscle development and therefore are named nascent myofibers. Some of the nascent myofibers do not react with the antibody to both slow‐tonic MHCs, indicating the lack of the normal adult slow‐tonic myosins which are expressed in 10‐day embryos. In order to explore the origin of the nascent fibers, an electron microscopic study was performed. Stereological analysis of the existing fibers shows a stimulation of numbers and sizes of satellite cells. In addition, the volume occupied by nonmuscle and undifferentiated cells increases dramatically. Myotube formation with incipient myofibrils is seen in extrafascicular spaces. These data suggest that new muscle fiber formation accompanies hypertrophy in overloaded chicken ALD muscle, and the process may involve satellite cell migration.
Pulmonary intravascular macrophages in domestic animal species: Review of structural and functional properties
Authors: Winkler Gian C.
Published: February 2005

In dogs, laboratory animals, and man, the clearance of bacteria and participates from blood occurs predominantly in hepatic Kupffer cells and splenic macrophages. In contrast, removal of blood‐borne particulates in calves, sheep, goats, cats, and pigs occurs predominantly in pulmonary intravascular macrophages (PIMs). Review of recent studies indicates that PIMs are a resident cell population, junctionally adherent to the capillary endothelium of lungs and morphologically similar to hepatic Kupffer cells. PIMs are a pulmonary constituent of the mononuclear phagocyte system with respect to secretory, endocytic, and functional properties. Differentiated PIMs are rare in newborn pigs, and the majority of cells closely apposed to capillary endothelium consists of monocytes, which are occasionally in mitosis. In 7‐day‐old and older pigs, most cells apposed to capillary endothelium have characteristics of differentiated PIMs. This suggests a monocytic origin of PIMs in pigs. Perinatal colonization of lung capillaries by monocytes and their subsequent differentation into PIMs represent a component of postnatal lung development. Estimates of relative PIM numbers in ovine and porcine lung parenchyma suggest cell densities similar to that of rat hepatic Kupffer cells. Apart from phagocytic properties, PIMs participate in the removal and disintegration of aged and impaired blood cells. After phagocytic stimulation, isolated PIMs secrete oxygen radicals, which are essential for microbicidal function. Similarly, by secreting bioactive lipids, stimulated PIMs may contribute to regulation of pulmonary hemodynamics. After receiving minute amounts of bacterial endotoxin, pulmonary injury is pronounced in sheep, calves, pigs, and cats, but not in laboratory animals and dogs. This presumably is related to the secretion of bioactive lipids by PIMs.
Microcirculatory pathways in normal human spleen, demonstrated by scanning electron microscopy of corrosion casts
Authors: Schmidt E. E. , MacDonald I. C. , Groom A. C.
Published: February 2005

Confusion regarding microcirculatory pathways in normal human spleen has arisen due to extrapolation from pathological material and from other mammalian spleens, not to mention difficulties in tracing intricate three‐dimensional routes from the study of thin sections or cut surfaces of tissue. We examined microcirculatory pathways in normal human spleens freshly obtained from organ transplant donors. A modified corrosion casting procedure was used to obtain an open view of vessels and their connections. Our results demonstrate: (1) „arteriolar‐capillary bundles”︁ within lymphatic nodules and extensive branching of arterioles; in the marginal zone (MZ); (2) the marginal sinus around lymphatic nodules; (3) the peri‐marginal cavernous sinus (PMCS) outside the MZ or immediately adjacent to the nodule itself; the PMCS receives flow via ellipsoid sheaths and MZ, or directly from arterial capillaries, and drains into venous sinuses; (4) fast pathways for flow into venous sinuses via ellipsoid sheaths; (5) arterial capillary terminations in the reticular meshwork of the red pulp or MZ („open”︁ circulation); direct connections to venous sinuses also occur („closed”︁ circulation), although rarely; and (6) numerous open‐ended venous sinuses in the MZ, allowing a large proportion of the splenic inflow to bypass the red cell filtration sites in the reticular meshwork and at venous sinus walls.
Cytoarchitecture of the fetal murine soleus muscle
Authors: Ontell Marcia , Bourke Dianna , Hughes Donna
Published: February 2005

The organogenesis of the soleus muscle of the 120 ReJ mouse (a mixed muscle, which in the adult contains approximately equal numbers of slow‐twitch oxidative and fast‐twitch oxidative‐glycolytic myofibers) was studied in spaced, serial transverse, and longitudinal sections of muscles of 14‐, 16‐, and 18‐day in utero and 1‐ and 5‐day postnatal mice. A discrete soleus muscle was distinguished by 14 days in utero. It consisted of groups of closely apposed primary myotubes displaying junctional complexes and a pleo‐morphic population of mononucleated cells. Between 14 and 16 days in utero there was little de novo myotube formation. At 16 days in utero, basal lamina surrounded groups of primary myotubes; and primitive motor endplates were found on these myotubes. At 18 days in utero, the basal‐lamina‐enclosed groups of primary myotubes were no longer present. At this stage, basal lamina surrounded clusters (consisting of one primary myotube and one or more secondary myotubes) or independent myotubes (single myotubes surrounded by their own basal lamina). Cluster formation and cluster dispersal occurred concurrently, beginning at 18 days in utero and extending until birth. At birth, there was still a substantial population of immature, secondary myotubes that interdigitated with larger, more mature primary myofibers. At this stage, intermuscular axons had begun to myelinate, and posteynaptic specialization of the motor endplates had begun. Cluster dispersal and myonuclear migration was completed during the first 5 days postnatally with the muscle taking on adult characteristics. Beginning at 16 days in utero and extending into the neonatal period, there was evidence of myotube death in the soleus muscle.
Morphometric analysis of the developing mouse soleus muscle
Authors: Ontell Marcia , Hughes Donna , Bourke Dianna
Published: February 2005

The pattern of organogenesis of the soleus muscle of the 129 ReJ mouse was evaluated quantitatively using spaced, serial, ultrathin sections and computer‐assisted morphometric analysis. Muscles from 14‐, 16‐, and 18‐day in utero mice and muscles of 1‐ and 5‐day‐old mice were analyzed to determine age‐related alterations in the maximal girth and length of the muscle, number of myotubes, cluster frequency, and the lengths and diameters of myotubes. Primary myotubes are found in the muscle at 14 days in utero. There is little de novo myotube formation between 14 and 16 days in utero, this interval being principally one of primary myotube growth and maturation. The interval between 16 and 18 days in utero is marked by extensive secondary myotube formation, with more myotubes being formed during this period than in any period studied. Morphometric data support the hypothesis that secondary generation myotubes use primary myotubes as a scaffold on which they are formed. Morphometric data also confirm the hypothesis that cluster formation and cluster dispersal occur concurrently during the prenatal period. Secondary myotubes continue to form until birth. At birth, the soleus muscle contains the adult number of myofibers. The first 5 days postnatally are marked by myofiber growth and maturation.
Light and electron microscopic observation on the cervical epithelium of the rabbit. I
Authors: Odor D. Louise , Blandau Richard J.
Published: February 2005

The light and electron microscopy of the cervical epithelium of ovulatory, estrous, and long‐term ovariectomized rabbits have been studied to determine what structural changes occur under different hormonal conditions. The percentage of nonciliated secretory cells is 49.6 in ovulatory, 43.6 in estrous, and 23.7 in long‐term ovariectomized rabbits, and of ciliated cells is 50.2 in ovulatory, 56.2 in estrous, and 76.3 in long‐term ovariectomized animals. The values for the ovulatory and estrous rabbits are significantly different at the P <0.05 level from those of the ovariectomized animals.

In all 3 groups the general ultrastructure of the normal ciliated cells is similar. Interestingly, the Golgi complex is very prominent in all. Glycogen bodies occur frequently only in ciliated cells of ovariectomized and occasionally of estrous animals. Abnormalities in cil‐iation are quite common in the ovariectomized rabbits.

The structure of the nonciliated secretory cells varies appreciably within and between the 3 groups. In these cells from well‐developed epithelia of certain ovulatory and estrous animals, the apical cytoplasm contains secretory granules of at least three types. In addition, very irregularly shaped, dense, perinuclear granules occur, which may be another type of secretory granule or lysosomes. As compared to ciliated cells, the secretory cells have less prominent Golgi complexes, more abundant bundles of intermediate filaments, a more extensive glycocalyx on their apical surface, and more heterochromatic nuclei. In comparison to the cells of well‐developed epithelia, the nonciliated cells of some other ovulatory and estrous rabbits are less well differentiated with fewer or no secretory granules and less well developed organelles. In the nonciliated cells of the long‐term ovariectomized rabbits, there are no secretory or dense perinuclear granules. There is a decrease in the number of organelles that are involved in secretion, in the size of the cells, and in the amount of nuclear euchromatin.
Formation and differentiation of extraembryonic mesoderm in the rhesus monkey
Authors: Enders Allen C. , King Barry F.
Published: February 2005

Differentiation of extraembryonic mesoderm in the rhesus monkey was studied from the epithelial penetration stage of implantation (stage 4) through the first week of postimplantation development (to stage 6). It was found that the first cells that appeared between the primitive endoderm (hypoblast) and trophoblast were separated from the latter by a basal lamina but appeared to be either loosely attached to the endoderm or to have been detached from it. Cells in this intermediate position differentiated cytologically into mesenchymal cells, which, by stage 5, had a distinctive intraendoplasmic reticulum marker. This differentiation occurred prior to the time at which the primitive streak could be recognized. By the time the primitive streak was readily discernible (stage 6), the extraembryonic mesoderm had already produced substantial extracellular matrix. The sequence of differentiation was repeated, with a 1‐ to 2‐day lag, in the secondary implantation site. No evidence of a contribution from cytotrophoblast or primitive streak to the extraembryonic mesoderm was found. It is concluded that the origin of the first extraembryonic mesoderm in the rhesus monkey is probably a two‐step process, with formation of a reticulum from primitive endoderm followed by differentiation in situ into mesenchymal cells. The first blood vessels formed also differentiated in situ from the extraembryonic mesenchymal cells. Primitive capillaries were identifiable as early as the 13th day of pregnancy.
Three‐dimensional network of cords: The main component of basement membranes
Authors: Inoue S. , Leblond C. P.
Published: February 2005

Basement membranes were divided into two types: (1) thin basement membranes, such as those of the epidermis, trachea, jejunum, seminiferous tubule, and vas deferens of the rat, the ciliary process of the mouse, and the seminiferous tubule of the monkey, and (2) thick basement membranes, such as the lens capsule of the mouse and Reichert's membrane of the rat. High‐magnification electron microscopy was used to examine both types after fixation either in glutaraldehyde followed by postosmication or in potassium permanganate.

The basic structure of thin and thick basement membranes was found to be a three‐dimensional network of irregular, fuzzy strands referred to as “cords”; the diameter of these cords was variable, but averaged 4 nm in all cases examined. The spaces separating the cords differed, however. In the lamina densa of thin basement membranes, the diameter of these spaces averaged about 14 nm in every case, whereas in the lamina lucida it ranged up to more than 40 nm. Intermediate values were recorded in thick basement membranes. Finally, the third, inconstant layer of thin basement membranes, pars fibroreticularis, was composed of discontinuous elements bound to the lamina densa: i.e., anchoring fibrils, microfibrils, or collagen fibrils. In particular, collagen fibrils were often surrounded by processes continuous with the lamina densa and like‐wise composed of a typical cord network. Finally, two features were encountered in every basement membrane: (1) a few cords were in continuity with a 1.4‐ to 3.2‐nm thick filament or showed such a filament within them; the filaments became numerous after treatment of the seminiferous tubule basement membrane with the proteolytic enzyme, plasmin, since cords decreased in thickness and could be reduced to a filament, and (2) at the cord surface, it was occasionally possible to see 4.5‐nm‐wide sets of two parallel lines, referred to as “double tracks”.

On the basis of evidence that the filaments are type IV collagen molecules and the double tracks are polymerized heparan sulfate proteoglycan, it is proposed that cords are composed of an axial filament of type IV collagen to which are associated glycoprotein components (laminin, entactin, fibronectin) and the double tracks of the proteoglycan.
Ultrastructural observations on human sublingual gland
Authors: Riva Alessandro , Tandler Bernard , Riva Francesca Testa
Published: February 2005

That part of the human sublingual gland that corresponds in morphology to the conventional description of this organ presented in most histology texts (probably the major sublingual gland, in contradistinction to the aggregated small glands that compose the minor sublingual glands) was studied by electron microscopy. The gland is mixed, with slightly more mucous elements than seromucous ones. The mucous cells are arranged in tubules that usually are capped by seromucous demilunes. Seromucous cells also form occasional acini or may be scattered in the walls of the mucous tubules. The appearance of the mucous cells varies with the stage of the secretory cycle that they may be in. Their secretory droplets increase in number and progressively compress cytoplasmic organelles. Filamentous bodies also may be present. Based on secretory‐granule substructure, four different kinds of seromucous cells can be recognized; these may be a morphological expression of asynchronous synthesis of different secretory proteins. The duct system is an abbreviated one compared to the other major salivary glands. The first duct segments, into which the mucous tubules drain, are similar to intercalated ducts. Larger ducts contain mitochondria‐rich cells but lack the basal striations that characterize striated ducts. The paucity of typical striated ducts may be correlated with the elaboration of sodium‐rich saliva by the human sublingual gland.
Endocytosis in the epithelium of the mouse oviduct
Authors: Parr Earl L. , Tung Hai‐Nan , Parr Margaret B.
Published: February 2005

We studied the pathway of serum protein transport into the lumen of the mouse oviduct by localizing several tracer proteins in the oviduct after intravenous injection on days 1, 5, and 11 of pregnancy. Fluorescent proteins were observed in the lamina propria and in vesicles in the lumenal epithelial cells mainly in the preampulla segment on days 5 and 11 of pregnancy. In the isthmus, there was much less fluorescence in the lamina propria and no fluorescent vesicles in lumenal epithelial cells. This is similar to previous observations on day 1 and indicates that the uptake of serum proteins into lumenal epithelial cells in the preampulla is not limited to the time when embryos are present in the oviductal lumen. Horseradish peroxidase (HRP) was present in the lamina propria of the preampulla on days 1 and 5, but direct tracer movement into the oviductal lumen was blocked by the epithelial junctional complexes. Within the epithelial cells, HRP was localized in endocytic vesicles along the basolateral membrane, multivesicular bodies (mvb), elongated dense bodies below the nucleus (bdb), and many small vesicles near the apical surface of the cells. Ferritin was also used as a tracer and was observed in the same locations as HRP. Acid phosphatase in the epithelial cells of the preampulla on day 1 was localized in mvb and bdb, indicating that these structures are lysosomes. It appeared that HRP and ferritin followed two pathways after basolateral endocytosis by the epithelial cells in the preampulla: (1) they were transported to apical vesicles that may release their contents into the oviductal lumen, or (2) they were transported to lysosomes. These observations suggest the occurrence of an intracellular vesicular transport system in the preampulla for the transfer of serum proteins to the oviductal lumen in mice.
Splenic hemopoiesis of the platypus (Ornithorhynchus anatinus): Evidence of primary hemopoiesis in the spleen of a primitive mammal
Authors: Tanaka Yasukazu , Elshi Yoshinobu , Morris Bede
Published: February 2005

The generation of blood cells has been observed in the spleen and in the bone marrow of the platypus. Hemopoiesis was found to be far more active in the spleen than in the bone marrow judging by the number of proliferating hemopoietic elements within a unit area of tissue from each organ. Granulocytes, erythroblasts, and megakaryocytes, with the related immature forms for each cell line, were noted in the spleen. In contrast, there were very few examples of immature forms of these cell lines and a complete absence of mature megakaryocytes in the bone marrow. These findings suggest that the spleen is the primary hemopoietic organ in the platypus. Since the platypus is one of two species representing the most primitive existing mammals, it seems likely that the spleen may be the primary hemopoietic organ in mammalian evolution.
Electron microscopic study of the prenatal development of the thoracic aorta in the rat
Authors: Nakamura Hiroaki
Published: February 2005

Prenatal development of the thoracic aorta of the rat during the period ranging from gestational days 12 to 21 was examined by transmission electron microscopic and morphometric studies. The process of wall formation occurred in four major phases. At phase I (gestational day 12), the dorsal aorta consists of an endothelium and loosely surrounding mesenchymal cells. Collagen fibrils and fine filamentous materials are sparsely present in the intercellular space. At phase II (days 13 to 16), the mesenchymal cells begin to differentiate to myoblasts, which have small clusters of myofilaments with dense bodies, rough endoplasmic reticulum, and a discontinuous basal lamina. The differentiating cells form a few compact cell layers around the endothelium. Elastic fibers first occur sparsely in juxtacellular spaces at days 13–14. The thickness of the aorta increases rapidly from 1–3 layers of cells at day 13 to 5–8 layers at day 17, leading to a maximum of 5–9 cell layers at day 20. The differentiation of myoblasts and elastogenesis are initiated in the inner layers, and later progress toward the outer layer of the aortic wall. At phase III (days 17 to 19), the myoblasts continue to develop into typical smooth muscle cells, and elastic fibers rapidly increase in both size and number. At phase IV (day 20 and later), smooth muscle cells have well‐developed myofilaments in the cell periphery, and rough endoplasmic reticulum and other organelles tend to accumulate in the apical portion of the cytoplasm. Elastic laminae appear in a few inner layers of the aortic wall.
Detection and quantification of CUPED, an estrogen‐dependent uterine protein, in uterine fluid and endometrial tissue of estrous and pregnant cats
Authors: Verhage Harold G. , Fazleabas Asgerally T. , Mavrogianis Patricia A. , Jaffe Randal C.
Published: February 2005

Uterine flushings, media from cultured endometrial explants, and endometrial tissue obtained from estrous and pregnant cats were analyzed for the presence of a previously characterized, high‐molecular‐weight, estrogen‐dependent glycoprotein (CUPED) by polyacrylamide‐gel electrophoresis, Western blots, radioimmunoassay, and immunocytochemistry. Elevated levels of CUPED were present within the flushings, media, and tissue of estrous and 3‐day postcoital animals. High levels of CUPED were also present in the flushings of 5‐day postcoital animals; but the ability of endometrial explants to synthesize CUPED during short‐term culture was greatly reduced, and only some of the endometrial glands contained CUPED secretory granules. CUPED was essentially nondetectable in the flushings, media, and tissues of animals pregnant for 7 or more days. Thus CUPED is present within the uterine lumen of the cycling cat at the time of sperm migration through the uterus and also for the first day or two that the developing blastocyst is present within the uterine lumen. The disappearance of CUPED from the tissue and flushings was correlated with the luteal production of progesterone.