bluuebunny/crossref_metadata_2025 huggingface dataset:
SEM characterization of a cellular layer separating blood vessels from endoderm in the quail embryo
Authors: Reiss Karen Z. , Noden Drew M.
Published: February 2005

The associations between the developing blood vessels and both endoderm and splanchnic mesoderm in quail embryos at stages 9–11 were examined by using scanning electron microscopy. Embryos were pinned ventral‐side up on agar plates and the endoderm was surgically removed prior to fixation and dehydration. This procedure exposes a netlike layer of cells closely apposed to the ventral surface of paraxial mesoderm and all visible blood vessels; we are calling this the subvascular layer. Development of this layer proceeds rostral‐to‐caudal, and lateral‐to‐medial, with the earliest stages of formation being visible over the unsegmented paraxial mesoderm of the segmental plate. The subvascular layer increases markedly in density slightly medial to the innermost boundary of the intraembryonic vascular plexus. Cells of this layer eventually establish a continuous sheet beneath the lateral plate and paraxial mesoderm and the notochord. With maturation, the cells of the subvascular layer approach confluence. The spatial and temporal patterns of development of the embryonic vascular tissues and the subvascular layer are closely correlated, suggesting a possible role for the subvascular layer in normal embryonic vascular development.
Use of nude (athymic) mice for the study of hypertrophic scars and keloids: Vascular continuity between mouse and implants
Authors: Ward Kischer C. , Sheridan Don , Pindur Jana
Published: February 2005

Hypertrophic scars and keloids appear to be unique to humans since animals are not known to form these lesions. Therefore, in an effort to develop an experimental model for their study, implants of these human lesions were made in nude (athymic) mice (nu/nu) in suprascapular subcutaneous pockets. The implants were recovered from 2 to 246 days. By histological and fine structural parameters all implants remained viable and their morphological character was maintained. Selected mice were injected with barium to confirm by microangiography vascular flow between mouse and implant. Hoechst stain for DNA, used to distinguish mouse cells from human cells, confirmed vascular anastamosis between host and implant: barium‐filled vessels in the interior of the implant demonstrated human endothelial cells. Peripheral vascularization of the implant with minimal ingrowth of mouse vessels occurs during the first 8 days. Anastamosis probably occurs sometime before 16 days postimplantation, or earlier, depending upon the availability of patent microvessels in the implanted tissue. The presence of the implant does not appear to prompt a continuing vascular growth into or throughout the implant. The time frame of 16 days postimplantation should be taken into account when developing schemata of experimental or therapeutic modalities.
Vestibular system of the newborn marsupial cat Dasyurus hallucatus
Authors: Gemmell R. T. , Nelson J.
Published: February 2005

The ultrastructure of the ear of the newborn native cat was examined to determine whether the vestibular system contained sensory receptors. A sensory region, presumably the utricle, was identified in each ear and consisted of a discrete population of otoliths overlying a sensory epithelium which possessed kinocilia and stereocilia. The remainder of the vestibular system did not appear to be developed anatomically. The newborn cat has rudimentary vestibular, olfactory, and mechanoreceptors (Merkel cells), and these structures may aid the newborn marsupial in the journey from the urogenital sinus to the pouch and in locating the teat.
Alteration of early vascular development after ablation of cranial neural crest
Authors: Bockman Dale E. , Redmond Mary E. , Kirby Margaret L.
Published: February 2005

A previous study has shown that, subsequent to ablation of cranial neural crest, heart morphology and pharyngeal arch vessels (aortic arches) are altered before septation of the outflow tract normally occurs. In the present study, we concentrated on very early development of the aortic arch apparatus in the chick (incubation days 3–5). The three‐dimensional organization of the arch vessel apparatus was studied by scanning electron microscopy after intravascular injection of Mercox, and by serial sections of embryos embedded in plastic. Alterations in the arch vessel apparatus were already present by day three in embryos with neural crest ablation at stage 9–10. Bilateral symmetry frequently was lost. Arch vessels sometimes were enlarged and occupied most of the arch, with little surrounding mesenchyme. Some arch vessels were small or occluded. Mesenchyme was significantly reduced in quantity in the arches, and was not condensed and symmetrical as in controls. There was a significant increase in the proportion of direct apposition of vessel endothelium with epithelium, without the intervening mesenchyme typical of controls. The surgical manipulation used in this study leads to distinct alterations in the arches of components and relationships which are important in development. Altered blood flow likely affects the development of the heart.
Ultrastructural localization and identification of adrenergic and cholinergic nerve terminals in the olfactory mucosa
Authors: Zielinski Barbara S. , Getchell Marilyn L. , Wenokur Randall L. , Getchell Thomas V.
Published: February 2005

Pharmacological and ultrastructural methods were used to demonstrate alpha‐adrenergic regulation of secretory granule content of acinar cells of Bowman's glands and to localize and identify adrenergic and cholinergic axonal varicosities and terminals in the olfactory mucosa of the tiger salamander.

The alpha‐adrenergic agonist phenylephrine caused secretory granule depletion from Bowman's glands; the alpha‐adrenergic antagonist phentolamine partially blocked this effect. These observations were quantified using light microscopic computer‐assisted morphometric techniques. Both drugs caused morphological signs of electrolye/water transport.

Adrenergic axonal varicosities were identified by the presence of small granular vesicles (SGVs, 45–60 nm in diameter) containing electron‐dense material that was enhanced by 5‐hydroxydopamine loading and chromaffin reaction fixation techniques. Throughout the lamina propria, small fascicles with axons containing SGVs as well as varicosities and terminals with SGVs were located adjacent to blood vessels, Bowman's gland acini, and melanocytes. Mean vesicle diameters at these sites were 54 ± 7 nm, 50 = 9 nm, and 56 ± 8 nm, respectively; varicosities were located approximately 0.1–1.0 μm from their presumed cellular targets. Axonal varicosities containing small agranular vesicles (AGVs, 65 ± 8 nm in diameter), identified as cholinergic by their size and by the absence of electron‐dense material after 5‐hydroxydopamine loading and chromaffin reaction fixation, were located between adjacent acinar cells. In addition, adrenergic varicosities containing SGVs (56 ± 6 nm in diameter) were found within 1 μm of blood vessels associated with Bowman's gland ducts and sustentacular cells near the base of the olfactory epithelium.

These results characterize the ultrastructural basis for adrenergic and cholinergic regulation of vasomotor tone and secretion within the olfactory mucosa.
Complex anomalies of the human aortic arch system: Unique case with both vertebral arteries as additional branches of the aortic arch
Authors: Schwarzacher Stephan W. , Krammer Eva B.
Published: February 2005

We describe a case of an aortic arch with five primary branches arising in a sequence that has previously never been reported. From right to left, the brachiocephalic trunk and left common carotid, left vertebral, and subclavian arteries originated from the convexity of the aortic arch. The last branch was the right vertebral artery that arose from the dorsal aspect of the aortic arch opposite the ligamentum arteriosum. Presenting a dilatation at its commencement, the right vertebral ran to the right behind the esophagus and entered the foramen transversarium of the seventh cervical vertebra, whereas the left vertebral passed to the foramen transversarium of the fifth cervical vertebra. The left vertebral artery gave off the left thyroid artery; a thyrocervical trunk was absent on the left side. A thyroidea ima arose from the brachiocephalic trunk. The embryology of this complex anomaly as well as its potential clinical significance are discussed.
Localization of serotonin‐like immunoreactivity in the merkel cells of pig snout skin
Authors: García‐Caballero T. , Gallego R. , Rosón E. , Basanta D. , Morel G. , Beiras A.
Published: February 2005

The presence of serotonin in the Merkel cells of pig snout epidermis was investigated by the peroxidase‐antiperoxidase immunohistochemical technique. Serotonin‐like immunoreactive Merkel cells were found in groups located at the base of epidermal rete pegs and in the external root sheath of sinus hair follicles (vibrissae). Immunoreactivity was stronger on the basal side of the Merkel cells, where dense‐cored granules are most numerous. Neither the nerve terminal associated with the Merkel cell nor the neighbouring epidermal cells were immunostained.

These results are the first evidence of serotonin‐like immunoreactivity in mammalian Merkel cells. The fact that immunoreactivity is strongest in those parts of the Merkel cells with the highest granule density suggests that in these cells serotonin is probably localized in the dense‐cored granules.
Cytodifferentiation of two epithelial populations of the respiratory bronchiole during fetal lung development in the rhesus monkey
Authors: Tyler Nancy K. , Hyde Dallas M. , Hendrickx Andrew G. , Plopper Charles G.
Published: February 2005

This study describes the cytodifferentiation of the two populations of epithelial cells found in the respiratory bronchiole of the adult rhesus monkey. One population, pseudostratified and containing ciliated, nonciliated secretory, and basal cells, is found overlying the pulmonary artery (PA). The other population, not associated with the PA, contains nonciliated cuboidal cells between alveolar outpockets. In this study we used terminal conducting airways from the lungs of fetal (90 to 155 days gestational age [DGA]), postnatal, and adult rhesus monkeys. Ciliated cells were partially differentiated at 90 DGA (54% gestation) and completely differentiated by 134 DGA (80% gestation). Nonciliated secretory cells were partially differentiated at 95 DGA (57% gestation) but did not lose all glycogen until the postnatal period. Basal cells appeared by 134 DGA (80% gestation) and matured in the postnatal period. Small mucous granule cells appeared at 125 DGA (74% gestation) and did not change throughout fetal development. Neuroendocrine cells were present throughout the entire period studied. Nonciliated cuboidal bronchiolar cells of the nonciliated population of the respiratory bronchiole appeared at 105 DGA (62% gestation) and matured in the postnatal period. We conclude that 1) although most of the differentiation of the lower airway occurs before birth, most of the cell types are not completely differentiated at birth; 2) the sequence of differentiation for the cells of the ciliated pseudostratified epithelial population is ciliated, nonciliated secretory, and basal; 3) the sequence of differentiation for the nonciliated secretory cell is similar to that of the secretory cells in more proximal airways; and 4) basal, neuroendocrine, and small mucous granule cells are not a part of the differentiation sequence of the other cell types.
Embryonic development of the posterolateral structures of the knee
Authors: Oransky Michel , Canero Gianfranco , Maiotti Marco
Published: February 2005

The development of the structures in the posterolateral corner of the knee was studied in fifteen human embryos and seventeen fetuses by means of serial sections in the coronal and sagittal planes. The attachments of the lateral meniscus and fibular head to the popliteal tendon and muscle are formed during the process of cavitation that forms the bursa. The connection between the tendon and the posterior border of the lateral meniscus forms obliquely to follow the direction of the muscle and tendon. The edge of the bursa is limited by attachments that connect the tendon to the lateral meniscus and fibular head. In this study, no direct ligamentous continuity was found to exist between the posterolateral femur and tibia during development. The only ligament that indirectly connects the lateral femur posteriorly to the proximal segment of the tibia, which has never been reported in human development, is the one that links the popliteal tendon to the fibular head. We have designated this the popliteo fibular ligament which was also found in adult specimens. This ligament should not be confused with the arcuate popliteal ligament.
Ultrastructure of the myocardium of the least shrew, Cryptotis parva say
Authors: Forbes M. S. , Mock O. B. , Van Niel E. E.
Published: February 2005

The heart of the least shrew, Cryptotis parva Say, is an extremely active organ, capable of achieving rates of 800—1,200 beats/minute. The general features of myocardial cell ultrastructure in this insectivore are much like those of other small mammals; no single striking feature of fine structure is present to which the physiological properties of this heart might necessarily be attributed. Still there exist in these myocardial cells a number of atypical properties. These include (1) mitochondria having a wide variety of sizes and internal configurations (2) a pleiomorphic, highly ramified, small‐diameter transverse‐axial tubular system (TATS) (3) numerous “labyrinths,” which are proliferated components of the TATS, and (4) myofibril‐free regions, located both in juxtanuclear and other myoplasmic levels and populated by a concentration of TATS elements and fibrillar structures. Features (2) and (3) are also characteristic of another fast‐beating heart, that of the mouse. The sinoatrial and atrioventricular nodal regions, as well as a Purkinje system, have been identified in the least shrew heart, along with sparsely distributed atrial cells whose myofibrils contain proliferated Z‐band material. A feature frequently encountered in atrial working muscle cells is the occurrence of close appositions between gap junctions and tubules of sarcoplasmic reticulum; such appositions are also present in other regions of the shrew heart, as are complexes composed of gap junctions and mitochondria.
Case with a high‐positioned origin of the testicular artery
Authors: Shinohara Harumichi , Nakatani Toshio , Fukuo Yoshifumi , Morisawa Satoshi , Matsuda Takeshi
Published: February 2005

In a Japanese male, the left testicular artery originated from the aorta as high as 1 cm cranial to the origin of the left inferior phrenic artery. The testicular artery emitted two branches, one to the costal part of the diaphragm and the other to the suprarenal gland. This testicular artery is the most highly positioned one that has ever been reported.
Patterns of skeletal histologic change through time: Comparison of an archaic native american population with modern populations
Authors: Burr David B. , Ruff Christopher B. , Thompson David D.
Published: February 2005

This paper compares patterns of histologic change in an archaic Native American population with those in modern white populations. Histologic sections were removed from core biopsies taken from the anterior femoral cortex of an archeologic sample of Pecos Indians. The data demonstrate many microstructural similarities between the Pecos and modern populations, even though they were genetically and culturally distinct. Pecos women had small Haversian canals and large osteon mean wall thickness, with no clear evidence of an intracortical bone volume deficit even in the older age groups, although significant marrow cavity expansion occurred in both males and females with age. No striking relationships were found between bone tissue changes and gross geometric changes with age. The data suggest that a more active life‐style is associated with greater osteon mean wall thickness or osteon population density, but that it alone does not protect against significant bone loss on the cortical‐endosteal surface.
Neuronal regulation of substrate cycle between glucose 6‐phosphate and glucose in brown adipose tissues of cold‐exposed mice
Authors: Suzuki Hiroshi , Watanabe Jun , Itani Tsuyoshi , Ogawa Ryokei , Kanamura Shinsuke
Published: February 2005

The increase in both glucose 6‐phosphatase and hexokinase activities in brown adipose tissues of cold‐exposed mice probably relates to thermogenesis by the substrate cycle between glucose 6‐phosphate and glucose (Watanabe et al.: Anatomical Record 219:39—44, 1987). To clarify the factors causing the simultaneous increase, we examined biochemically the effects of uni‐ or bilateral surgical denervation of brown adipose tissues, of adrenalectomy, or of streptozotocin injection on the increase in the two activities in the tissues of cold‐exposed mice. Further, the effects of denervation on the increase were also examined histochemically. The simultaneous increase in the two activities was inhibited in the denervated tissues of cold‐exposed animals in biochemical and histochemical experiments. However, the increase in the activities was not inhibited in the tissues of animals exposed to cold after adrenalectomy or streptozotocin injection. The results suggest strongly that the activation of the substrate cycle in brown adipose tissues of cold‐exposed mice is caused by a transmitter released from sympathetic nerve endings, probably norepinephrine.
Endorphin suppresses FSH‐stimulated proliferation of isolated neonatal sertoli cells by a pertussis toxin‐sensitive mechanism
Authors: Orth Joanne M. , Boehm Rosemarie
Published: February 2005

During perinatal development, when the size of the Sertoli cell population is determined, Leydig cells produce β‐endorphin, a peptide which may interact with Sertoli cells to modify their FSH‐responsiveness, as suggested by our previous work. The goal of the present study was first, to test directly the possibility that β‐endorphin modifies the proliferative response of neonatal Sertoli cells to FSH, and second, to gain information on a mechanism(s) involved in any observed effect. We treated isolated 6‐day‐old Sertoli cells with FSH or vehicle in vitro and measured their incorporation of exogenous, radiolabeled thymidine with quantitative autoradiography. After 2 days in culture with FSH, we detected a 10‐fold increase in the rate of Sertoli cell proliferation. The level of cell division in these FSH‐treated cultures was identical to that in other cultures exposed to cAMP under similar conditions. In addition, inclusion of β‐endorphin 3 hr prior to FSH or cAMP decreased the effect of the hormone by 50% but left the cAMP response unchanged. Thus, β‐endorphin acts on isolated, neonatal Sertoli cells at a point prior to intracellular production of cAMP to suppress their response to FSH. When other cultures were treated with pertussis toxin, a blocker of intracellular GTP‐binding proteins such as Gi, before sequential addition of endorphin and FSH, the effect of β‐endorphin on FSH‐responsiveness was abolished. Moreover, when other cultures were exposed to pertussis toxin in the absence of endorphin, followed by FSH, their response to the hormone was unchanged. Thus, β‐endorphin apparently modifies the proliferative response of neonatal Sertoli cells to FSH via a mechanism involving one or more G proteins. These observations, along with our previous data showing enhanced Sertoli cell division in vivo in the presence of an opiate blocker, point to the existence of endorphin‐mediated communication between Leydig and Sertoli cells during perinatal development and provide new evidence suggesting that paracrine mechanisms modify Sertoli cell function during perinatal development, when the size of this population is established.
Impaired elastic matrix development in the great arteries after ablation of the cardiac neural crest
Authors: Rosenquist Thomas H. , Beall Arthur C. , Módis Lászlo , Fishman Richard
Published: February 2005

The cells that form the aorticopulmonary septum in the avian embryo have been shown to be similar to the cells that form the walls of the great vessels in two ways: both are derived from the cardiac neural crest and both are able to synthesize an elastogenic matrix in the early embryo. Because of these similarities, and because ablation of the cardiac neural crest causes congenital defects of the outflow tract that are related to failure of proper septation, it was hypothesized that such an ablation also would cause the walls of the great vessels to be defective. The purpose of this study was to compare the elastic matrix in the mediae of the great vessels of normal embryos with those from which the cardiac neural crest had been ablated.

The results show that the elastic matrix in the great vessels of the experimental embryos was impaired (1) in the rate of downstream propagation of the initiation of elastogenesis among younger embryos, incubation days 4–8 and (2) in the spatial configuration of the elastic matrix among the older embryos, incubation days 16–20.

These results may provide a biological explanation for the elastin defect that affects the pulmonary artery of many patients with cyanotic congenital heart defects.
Changes in mesenchymal cell and hyaluronate distribution correlate with in vivo elevation of the mouse mesencephalic neural folds
Authors: Morris‐Wiman Joyce , Brinkley Linda L.
Published: February 2005

The mesenchyme of the elevating mesencephalic neural folds of the mouse is composed primarily of mesenchymal cells embedded in an hyaluronate‐rich extracellular matrix. In this study we provide evidence that hyaluronate and mesenchymal expansion may play a role in neural fold elevation and closure. Spatial and temporal patterns of mesenchymal cell and hyaluronate distribution were analyzed during neural fold elevation and closure using the computer‐assisted method of smoothed spatial averaging and established methods of image processing. Degree of fold elevation and fold shape changes were analyzed using standard morphometric measures. The results of these analyses defined five distinct stages in mesencephalic neural fold elevation and closure. Mesenchymal cells and hyaluronate were found in a non‐random distribution within the neural fold and showed distinct patterns of distribution which could be correlated with specific stages in neural fold elevation. The results of these analyses suggested that the elevation of the mesencephalic neural folds is produced by the expansion of an hyaluronate‐rich extracellular matrix in the central mesenchyme which under the direction of surrounding tissues pushes the folds mediad towards the dorsal midline.
Skeletal structural adaptations to mechanical usage (SATMU): 3. The hyaline cartilage modeling problem
Authors: Frost H. M.
Published: February 2005

A chondral growth/force response curve predicts how intact hyaline cartilage plates grow in vivo under typical peak mechanical unit loads and gradients thereof in healthy immature mammals. Growth under tension would increase as tension rises from zero to a level that damages the tissue. Under compression, growth would increase as the load rises from zero to a level at which growth becomes maximal (the growth‐ascending limb of the curve). Further increases in compression loads retard growth and large enough increases can stop it entirely (the growth‐descending limb of the curve). For equal changes in loads, the smallest growth change would occur under tension; the largest change would occur on the growth‐descending part of the curve. Under zero load a respectable “baseline growth” still occurs. Those effects are superimposed on inherent differences in growth potential of different chondral plates, differences that are determined partly in utero and by the genome.

The curve's features can explain many anatomical facts, including the ball‐and‐socket ankle, joint alignment in the valgus‐varus sense, hip dislocations in spasticity, different epiphyseal heights, short bones in paralysed limbs, long bone overgrowth after fractures, why some joint surfaces remain concave and others convex throughout growth, and why some growth plates are domed instead of flat. The above phenomena can be expressed mathematically, and a phenomenologic basic logical framework for doing that is suggested.
Melano‐macrophage centers in the aglomerular kidney of the sea horse (Teleosts): Morphologic studies on its formation and possible function
Authors: Tsujii Tadashi , Seno Satimaru
Published: February 2005

In order to elucidate the process of the formation and possible function of the renal “melano‐macrophage centers (MMC)” of fish, light and electron microscopic observations were carried out on the aglomerular kidney of the sea horse, Hippocampus kuda BLEEKER, injected with antigenic horse‐spleen ferritin (AF) and nonantigenic carbon particles (CP). Kidneys of the sea horse have well‐developed hemopoietic foci in the interstitial tissues surrounding the bundles of renal tubules. Each hemopoietic focus has a small artery in the central area and is framed with the densely arranged sinusoids lined with monolayered macrophages which have no melanin pigments. In the hemopoietic foci free macrophages (Mϕ) were hardly found, but large clusters or MMC filled with densely packed masses of cell debris with some melanin pigments were encountered. Some of them had degenerated Mϕ with fibrotic change surrounded by fibroblasts. AF and CP injected intraperitoneally entered quickly into blood vessels and were taken up actively by the sinusoidal Mϕ. The Mϕ full of AF or CP left the sinusoidal wall and moved gradually into hemopoietic foci to form the MMC or to fuse with the preexisting MMC. The melanophores in the interstitial connective tissue joined to form the MMC. No specific histologic change suggestive of immune response to the AF was present in and around the MMC. The results indicate that the MMC of fish should be only the aggregates of Mϕ to digest the ingested materials effectively. The process of formation of MMC and their possible function is discussed.
Sites of endometrial vascular leakage during implantation in the rabbit
Authors: Hoffman Loren H. , Winfrey Virginia P. , Hoos Paula C.
Published: February 2005

Vascular labelling with carbon suspension was used to identify endometrial vessels demonstrating macromolecular leakage at implantation sites in the rabbit. Extravasation was seen first in venous components of the deep endometrial stroma on the mesometrial aspect of implantation sites. Carbon labelling was apparent in such vessels at 7 d, 0 hr post coitum, (p.c.), and was attributed to gap formation between endothelial cells. Later in the implantation process, leakage was seen as microextravasations of carbon in the lateral and antimesometrial walls of implantation chambers. Here, penetration of vessels by trophoblast was apparent and membranous processes from the trophoblast projected into vessel lumina. Extravasated material (carbon, platelets) was localized to a labyrinthine system of membranes within the trophoblast, and a potential role for the labyrinth in handling of ingested plasma constituents is discussed. A similar process of trophoblastic penetration of vessels occurred on the mesometrial aspect of implantation sites several hours later. Systemic administration of the anti‐inflammatory agent indomethacin blocked vascular leakage due to endothelial gap formation but had little or no effect on trophoblast knob penetration of vessels. This observation may explain the results of previous studies in which treatment with anti‐inflammatory agents reduced, but could not inhibit completely, the vascular permeability changes at implantation sites.
Development of the conducting airway epithelium in fetal Syrian golden hamsters during normal and diabetic pregancies
Authors: McDowell Elizabeth M. , Coleman William P. , De Santi Andrea M. , Newkirk Carnell , Strum Judy M.
Published: February 2005

The conducting airway epithelium of fetal Syrian golden hamsters was studied from gestational day 12 to day 15, during normal and uncontrolled diabetic pregnancies. Diabetes was induced in the pregnant hamsters by injecting streptozotocin at 60 mg/kg body weight, subcutaneously, early on gestational day 10. Cells in S‐phase were labelled immunochemically with bromodeoxyuridine (BrdU), and the day on which endocrine cells and ciliated cells first appeared was determined.

In control fetuses, the BrdU‐labelling indices (LI's) of different anatomical airway levels were significantly different from one gestational day to the next. For example, the LI of the lobar bronchus was significantly different on each gestational day (P.0001), and the same was true of the bronchioles. Moreover, the difference between LI's of the lobar bronchus and bronchioles‐terminal buds was highly significant on day 12 (P <.0001), and on day 13 the differences between lobar bronchus and bronchioles, lobar bronchus and terminal buds, and bronchioles and terminal buds were also highly significant (P .0001). However, on gestational days 14 and 15, the LI's were reduced and were comparable at different airway levels. The BrdU‐labelling indices were very consistent among fetuses of the same age, and the differences between the average LI's for pups of different litters was numerically very small.

Hyperglycemia (mild, moderate, severe) did not alter LI's in the fetal airway epithelial cells. Furthermore, although glycogen was not depleted from the airway epithelium of the hyperglycemic fetuses as it was in the controls, the endocrine cells first appeared on gestational days 12, 13, and 14, respectively, in the trachea, lobar bronchus and bronchioles, followed 1 day later by the ciliated cells, in the fetuses of control and diabetic mothers. In our experimental model, induction of diabetes in the pregnant hamsters on gestational day 10 did not appear to alter development or diferentiation of the fetal conducting airway epithelium.
Polar trophoblast (Rauber's layer) of the rabbit blastocyst
Authors: Williams Betsey S. , Biggers John D.
Published: February 2005

The germinal area of the rabbit blastocyst between 108 h postcoitum (pc) and 168 h pc has been examined by scanning electron and transmission electron microscopy. At 108 h and 120 h pc the polar trophoblast (Rauber's layer) is an intact epithelium overlying the epiblast of the inner cell mass. By 132 h pc the polar trophoblast cells begin to separate at multiple foci, exposing the underlying epiblast. Most of the polar trophoblast cells have become individually separated at 144 h pc. The villous, electron‐dense polar trophoblast cells can be easily distinguished from cells for the epiblast, which have smooth apical surface. By 162 h pc the polar trophoblast cells have disappeared from the germinal area.

Before the polar trophoblast breaks up, the underlying epiblast cells are only loosely attached to one another. Concurrent with the disintegration of the trophoblast epithelium, the epiblast cells change in shape so that their lateral borders become closely apposed, and juctions develop to form a new epithelium. The epiblast becomes contiguous with the mural trophoblast, and thus the blastocyst does not lose its turgidity as the permeability sea is maintained.

There are two classical theories on the fate of the polar trophoblast: the cells die, or they become incorporated into the epiblast as living cells. In newly exposed epiblast the presence of very large phagosomes, which are not found when the polar trophoblast is still intact, favors the first hypothesis and indicates that in the rabbit the epiblast is involved in the phagocytosis of the polar trophoblast.
Glycogen metabolism in cultured chick hepatocytes: A morphological study
Authors: Parkes Joan Lee , Cardell Emma Lou , Grieninger Gerd , Cardell Robert R.
Published: February 2005

Ultrastructural and autoradiographic observations of cultured chick hepatocytes under the following conditins are described: Induction of glycogen synthesis with glucose alone and glucose plus insulin, and glucagon‐induced glucogen glucogen breakdown. Profiles of hepatocytes cultured in medium containig 10 mM glucose showed typical cellular organelles and occasionally a few glycogen granules. After incubation of hepatocytes with 3H‐glucose, silver grains were found over these sparse glycogen granules, indicating a low level of glycogen synthesis by a few cells. After addition of 75 mM glucose for 1 hr about 3% of the profiles of cells showed glycogen, and by 24 hr half of the hepatocytes had glycogen. Addition ofinsulin plus glucose induced glycogen synthesis in 82% of the cells after 6 hr. and by 24 hr almost every cellular profile showed glyocgen particles. Morphologically, glycogen accumulation was similar whether the cells were stimulated by high glucose or by glucose plus insulin: glycogen granules appeared in restricted regions of the cytoplasm, which were rich in smooth endoplasmic reticulum (SER), and peroxisomes were found close to the newly deposited glycogen particles. At maximum glycogen accumulation the association of SER and peroxisomes with glycogen was less obvious. Glycogenolysis induced by incubation of glycogen‐rich hepatocytes with glucagon resulted in proliferation of SER in the glycogen regions of the cells. These observations are compatible with the concept of regions in the hepatocyte cytoplasm specialized for glycogen metabolism. Possible roles for SER and peroxisomes found near glycogen particles and other organelles in hepatic glycogen metabolism are discussed.
Taste bud distribution in the rat pharynx and larynx
Authors: Travers Susan P. , Nicklas Kent
Published: February 2005

The present study evaluated the number and distribution of taste buds in the rat pharynx and larynx using light microscopic techniques. The average number of taste buds in this region was 141.9 (S.D. = 29.4, n = 10). Pharyngeal and laryngeal taste buds could be grouped into three subpopulations: those associated with laryngeal structures (LA), the nasopharynx (NP), or the palatopharyngeal eminence (PE). Laryngeal taste buds were most numerous (X = 103.2, S.D. =23.6). They were observed on the laryngeal surface of the epiglottis and extended caudally along the aryepiglottic folds, reaching peak density at the caudal extreme of the folds. Further caudally, when the larynx and rostral esophagus separated, taste bud density decreased sharply. Fewer taste buds were associated with the NP (X = 31.9, S.D. = 13.7) or PE (X = 6.8, S.D. =4.0) and taste bud density in these subpopulations peaked at the anterior border of the nasopharyngeal hiatus. Taste buds in the rat larynx and pharynx account for 10% all taste buds in this species, a proportion similar to that accounted for by taste buds on the soft palate. Taste buds in this region appear to be ideally situated for protecting the airway during accidental aspiration of food or fluids. Most pharyngeal and laryngeal taste buds are unlikely to be involved in triggering normally occurring swallows, although they could be stimulated as the bolus is propelled from the oral cavity to the esophagus.
Satellite cell response in rat soleus muscle undergoing hypertrophy due to surgical ablation of synergists
Authors: Snow Mikel H.
Published: February 2005

Although the role of satellite cells has been confirmed during skeletal muscle growth and regeneration, their involvement during work‐induced muscle growth remains uncertain. In this study, chronically overloaded rat soleus muscles were ultrastructurally monitored following surgical ablation of synergists to examine cytological adaptations of satellite cells and myofibers. The left soleus muscle of 20 female Spague‐Dawley rats (7 weeks of age) was induced to hypertrophy by excising the contralateral plantaris and gastrocnemius muscles under pentobarbital anesthesia. Right limbs were sham‐operated and served as controls. On days 3, 7, 14, 21, and 30 after surgery, the soleus muscles were removed and processed for electron microscopy. Two morphologically distinct phases were noted in the surgically overloaded muscles. The first stage (week 1) was characterized by a significant increase in the number of satellite cells, and by more than half of the experimental muscle fibers displaying myofibrillar disruptions, mitochondrial alterations and glycogen pooling. The second phase (weeks 2–4) featured mostly normal, although larger appearing muscle fibers, with the satellite cell frequency remaining slightly elevated. These findings suggest that muscle fiber structural abnormalities, rather than an increase in muscle activity, may play a more significant role in the early activation of satellite cells during compensatory hypertrophy, whereas activation of satellite cells during the later stages may be in response to increased levels of muscle activity.
Spatial distribution of “tissue‐specific” antigens in the developing human heart and skeletal muscle. I. An immunohistochemical analysis of creatine kinase isoenzyme expression patterns
Authors: Wessels A. , Vermeulen J. L. M. , Virágh S. Z. , Kálmán F. , Morris G. E. , Man Nguyen Thi , Lamers W. H. , Moorman A. F. M.
Published: February 2005

Using monoclonal antibodies against the M and B subunit isoforms of creatine kinase (CK) we have investigated their distribution in developing human skeletal and cardiac muscle immunohistochemically. It is demonstrated that in skeletal muscle, a switch from CK‐B to CK‐M takes place around the week 8 of development, whereas in the developing heart, CK‐M is the predominant isoform from the earliest stage examined onward (i.e., 4½ weeks of development). In all hearts examined, local differences in concentration of the CK isoforms are observed. The CK‐M expression in the developing outflow tract (OFT) and conduction system is described in detail. Between the weeks 5 and 7 of development, the distal portion of the OFT is characterized by low CK‐M expression, whereas around the week 8–10 of development the myocardium around the developing semilunar valves in the OFT expresses a very high level of CK‐M. At all stages examined, a relatively low CK‐M level is observed in those regions in which the “slow” components of the conduction system do develop (e.g., the sinoatrial junction and atrioventricular junction), whereas a relatively high concentration of CK‐M is observed in those areas that are destined to become the “fast” components, i.e., the subendocardial myocardium of the ventricles. The high expression of CK‐M in the developing “fast components” of the conduction system contrasts with the relatively low expression of CK‐M in the force‐producing myocardium of the interventricular septum and free ventricular wall.
Effects of purified Pasteurella multocida dermonecrotoxin on cartilage and bone of the nasal ventral conchae of the piglet
Authors: Martineau‐Doizé Beatrice , Frantz Joseph C. , Martineau Guy‐Pierre
Published: February 2005

The effect of intramuscular injection of purified dermonecrotoxin (DNT) from Pasteurella multocida type D on the nasal ventral conchae of piglets was studied. Severe atrophy of the conchae was observed 4, 6, and 10 days after injection (p.i.d.). Lesions were observed in conchae cartilage and bone. Cartilage changes observed were the absence of chondrocyte maturation and hypertrophy, hyaline cartilage invasion by fibroblast‐like and multinucleated cells, and endothelium damage with haemorrhages along the cartilage. Intramembranous bone was absent on p.i.d. 4, 6, and 10. Lamellar bone trabeculae were rarefied on p.i.d. 4 and almost absent on p.i.d. 10. Trabeculae were either normal or had the aspect of a dissolved bone matrix, leaving only irregularly oriented collagen fiber bundles. The number of osteoclasts was increased, especially the subperiosteal osteo‐clasts at the eccentric side of the scrolls. The osteoblasts appeared normal or their cytoplasm was dilated by vacuoles. It is concluded that the macroscopic conchae atrophy results from histological alterations and subsequent loss of both cartilage and bone. Further investigation is necessary to know whether the toxic effect of DNT on cells and matrix is direct or dependent of the vascular damage.
Ultrastructural study of lamellar and nucleolus‐like bodies in the harderian gland during postnatal development of the hamster (Mesocricetus auratus)
Authors: López J. M. , Tolivia J. , Díaz C. , Alvarez‐Uría M.
Published: February 2005

Membranous structures identified as lamellar bodies (LBs) and dense intracytoplasmic bodies referred to as nucleolus‐like bodies (NLBs) have been found in the hamster Harderian gland during neonatal stages. Both structures appear between 8 and 12 postnatal days, coinciding with the beginning of secretory activity. LBs in males and NLBs in both sexes gradually decrease in number with further differentiation of the glandular cells. The morphological features of these cytoplasmic structures are described, and their origin as well as their possible functional significance are discussed.
Ultrastructural evidence of mature Leydig cells and Leydig cell regression in the neonatal human testis
Authors: Prince Frederick P.
Published: February 2005

The neonatal period in male development is characterized by an acute rise in serum testosterone, which peaks at 2 to 3 months of age. The purpose of this study is to examine the neonatal human testicular interstitium at 4 months for evidence of Leydig cell maturation, as well as any morphological criteria relating to the fate of Leydig cells during this period, specifically, for signs of cell regression.

Leydig cells are described with impressive development of the steroid secreting apparatus, which are consistent with the mature Leydig cells found during early fetal development and in the adult. The outstanding feature of these cells is the “organelle association” of extensive, anastamosing tubules of smooth endoplasmic reticulum (SER), pleomorphic mitochondria with a component of tubular cristae, and abundant microperoxisomes associated with the SER. Well‐developed Golgi elements, regionalized RER, and diverse cell inclusions are also characteristics of these cells. Reinke crystals and paracrystalline inclusions are absent. Gap junctions are common in this system and are notable in the asymmetric nature of the adjacent cytoplasmic components.

These findings provide a morphologic correlate to the reported neonatal phase of testosterone production in man.

Intermediate forms of Leydig cells are described with “organelle associations” including decreased SER with increased lipid droplets, and decreased SER with prominent cytoplasmic filaments and/or dramatic mitochondrial changes supportive of mitochondrial involution. Cells consistent with immature Leydig cells are also present. The rather impressive diversity in cell morphology present during this time frame of 4 months, slightly past the peak in testosterone production, provides evidence of Leydig cell regression and a continuity of the mature neonatal Leydig cells with the immature Leydig cells of childhood (Prince, 1984). There is also some evidence of cell degeneration.

Although the developmental history of Leydig cells has been described for years as biphasic, it is time to view Leydig cell development in man as a triphasic event, fetal, neonatal, and pubertal.
Effects of maternal bilateral ureteral ligation on the development of the proximal tubule of the kidney in fetal rats: Morphometry and electron microscopic study
Authors: Okada Toshiya , Morikawa Yoshio
Published: February 2005

Development of the proximal tubule in the fetal kidney was studied following ligation of both ureters of pregnant rats. The ligation was performed on days 15, 17, 19, and 21 of gestation and autopsy followed 24 hours after each operation. On fetal days 20 and 22, the proximal tubular length per unit volume (1 mm3) of whole kidney of the fetuses from the ligatd mothers was significantly increased, while the ratio of total glomerular volume to total proximal tubular volume, was remarkably decreased when compared to that of the fetuses from the non‐ligated mothers. Apical vacuoles in proximal tubular cells were increased by the ligation on fetal days 20 and 22. These findings suggest that maternal bilateral ureteral ligation accelerates the growth and differentiation of the proximal tubule in fetal kidney, when the fetal kidney is functional in urine production.
Premitotic DNA synthesis in the brain of the adult frog (Rana esculenta L.): An autoradiographic 3H‐thymidine study
Authors: Bernocchi Graziella , Scherini Elda , Giacometti Silvia , Mareš Vladislav
Published: February 2005

Replicative synthesis of DNA in the brain of the adult frog was studied by light microscope autoradiography. Animals collected during the active period (May–June) and in hibernation (January) were used. In active frogs, 3H‐thymidine labelling occurred mainly in the ependymal cells which line the ventricles. The mean labelling index (LI%) was higher in the ependyma of the lateral and fourth ventricles than in the ependyma of the lateral diencephalon and tectal parts of the mesencephalon. In the recessus infundibularis and preopticus the number of labelled cells (LCs) was several times greater than in the lateral parts of the third ventricle. LCs were seen subependymally only occasionally. The incidence of LCs in the parenchyma of the brain was much lower in most regions than in the ventricular ependyma; LCs were mainly small and, from their nuclear morphology, they were glial cells. The LI% reached the highest value in the septum hippocampi and in the nucleus entopeduncularis. In these locations, LCs were larger and closer in size to the nerve cells of these regions. From comparison with data obtained earlier in the brain of mammals, it is evident that the distribution of proliferating cells in the olfactory and limbic system is phylogenetically conservative. The occurrence of pyknotic cells in the same areas which contain LCs, suggests that cell division reflects in part the process of cell renewal observed in mammals. However, proliferating cells could also be linked to the continuous growth observed in non‐mammalian vertebrates. In hibernating frogs, LCs and pyknoses were not seen or were found occasionally, which further indicates the functional significance of both processes.
Turnover of asymmetric unit membranes in the transitional epithelial superficial cells of the rat urinary bladder
Authors: Amano Osamu , Kataoka Seiki , Yamamoto Toshi Yuki
Published: February 2005

Asymmetric thick unit membranes were observed on the luminal surface, fusiform vesicles, and multivesicular bodies of superficial cells of rat transitional epithelium. When HRP‐labeled Ricinus communis lectin (RCA‐I) was injected into the rat urinary bladder, RCA‐I was deposited along the luminal cell membrane and in some multivesicular bodies, but not in the fusiform vesicles either before or after contraction. When the bladder was sliced by Vibratome and stained with HRP‐labeled RCA‐I after fixation, RCA‐I was observed in many cell organelles, including fusiform vesicles and multivesicular bodies as well as the luminal surface. When small pieces of tissue were stained en‐bloc with HRP‐labeled RCA‐I, RCA‐I was found along the luminal cell surface but not in the fusiform vesicles nor the multivesicular bodies. When HRP alone was injected into the bladder, HRP was observed in some multivesicular bodies after contraction but not in the fusiform vesicles. Various lysosomes were observed by electron microscopy. Some were wrapping multivesicular bodies in ringlike fashion, and some contained asymmetric unit membranes. These findings suggest that the asymmetric unit membranes are carried to the luminal cell membrane via the fusiform vesicles and that old luminal cell membranes are removed via the multivesicular bodies to be degraded by lysosomes.