bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitochondrial granule distribution in tooth germ cells
Authors: Sayegh F. S. , Abousy A.
Published: February 2005

Incisor and molar tooth germs of albino rats sacrificed at the eighteenth and twentieth days in utero and one to seven days after birth were studied with light and electron microscopy. Observations of the various stages of tooth development in molars established that intramitochondrial granules in odontoblasts were comparable to the intramitochondrial granules of other hard tissue cells. These electron‐dense deposits appeared in mitochondria in an appreciable number only when odontoblasts become engaged in dentin mineralization. When dentin mineralization was advanced the odontoblast mitochondria appeared devoid of these deposits. Mesenchymal cells and preodontoblasts of the pulp were not involved in this activity.
The site of remodelling of collagen in the periodontal ligament of the mouse incisor
Authors: Beertsen W. , Everts V.
Published: February 2005

In an attempt to localize the site of remodelling of collagen in the periodontal ligament of the continuously erupting mouse incisor a radioautographic and stereologic investigation was undertaken. Grain distributions in radioautographs for light microscopy were studied at various time intervals after administration of [3H]‐proline. The distribution of rough endoplasmic reticulum cisternae in fibroblasts and the incidence of collagen phagocytosis across the ligament were studied by means of stereologic methods at the electron microscopic level.

No significant differences were found in half lives of [3H]‐labelled substances among the various regions across the ligament. Roughendoplasmic reticulum cisternae within fibroblasts were distributed more or less uniformly throughout the entire width of the ligament. Analysis of the distribution of collagen phago‐cytosis, however, revealed that in the midregion of the ligament the amount of phagocytosed collagen was approximately four times as high as in the area adjcent to the tooth and about nine times as high as in the alveolar compartment.

It is concluded that synthesis and turnover of total protein occurs throughout the periodontal ligament but that remodelling of collagen predominantly takes place in an intermediate area of the ligament.
Muscle spindles in nonhuman primate extrinsic auricular muscles
Authors: Lovell M. , Sutton D. , Lindeman R. C.
Published: February 2005

Muscle spindles were sought in peri‐auricular muscles of several primate species (rhesus monkey, woolly monkey, and baboon). Transverse sections cut at 10 μ and stained primarily by a silver impregnation technique were examined using light microscopy. Spindles were identified on the basis of standard criteria. Posterior and/or superior auricular muscles of each species were found to contain spindles. At least some muscles innervated by facial nerve have classical spindles as component structures.
Intramembranous particle distribution in human erythrocytes: Effects of lysis, glutaraldehyde, and poly‐L‐lysine
Authors: Pricam Claude , Fisher Knute A. , Friend Daniel S.
Published: February 2005

Freeze‐fracture combined with quantitative electron microscopy of the intact human erythrocyte (RBC) and ghost revealed significant differences in their intramembranous particle coefficients. External (E) fracture‐faces of unfixed ghost membranes were found to contain 40% fewer particles than those of intact unfixed RBC. The particle distribution of the intact RBC membrane depended on the use of glutaraldehyde fixation and glycerol cryoprotection. Whereas glutaraldehyde‐ and glycerol‐treated cells disclosed 70% fewer E‐face particles than did intact unfixed cells, poly‐L‐lysine‐treated, intact, unfixed RBC showed no such differences. Treatment with a combination of poly‐L‐lysine and glutaraldehyde, however, increased the amount of E‐face particles while reducing those of the protoplasmic (P) face. The poly‐L‐lysine effect varied with its concentration and was unaffected by previous application of neuraminidase. Nor did the lectin phytohemagglutinin induce particle rearrangement in intact cells.

Our data demonstrate that the processes of glutaraldehyde fixation and glycerol cryoprotection modify the RBC membrane by decreasing the number of E‐face particles present. In addition, the combination of poly‐L‐lysine and glutaral‐dehyde alters the affinity of some particles for one half of the membrane, suggesting that in freeze‐fractured RBC, chemical bonds formed at the extracellular surface of the membrane can influence particle partitioning.
Neonatal muscle: An electron microscopic study
Authors: Ontell Marcia
Published: February 2005

A spaced serial section, electron microscopic study of the extensor digitorum longus of the 2‐day‐old rat was undertaken to determine whether all cells wedged between the basement membrane and the sarcolemma of a muscle fiber, regardless of their morphology, were true myosatellite cells. The muscle was relatively immature, containing groups of cells enclosed in a common basement membrane (clusters) and exhibiting primitive myoneural junctions. Cells of the muscle line included in the clusters were primary fibers, satellite fibers, myotubes in different stages of development and myosatellite cells. In single ultrathin sections, some early myotubes lacked myofilaments and were difficult to distinguish from myosatellite cells. Spaced serial sections revealed that all myosatellite cells have heterochromatic nuclei and a high nuclear/cytoplasmic ratio, and that all pale staining nuclei were found in cells with a lower nuclear/ cytoplasmic ratio, containing variable quantities of myofilaments. In addition to the cells of the muscle line, mast cells, fibroblast‐like cells and other “unclassified” cells were entirely or partially enclosed within the cluster's basement membrane. This study demonstrated that location alone or location and the morphological appearance of cells in a single ultrathin section failed to provide sufficient criteria to properly classify all of the cells found in neonatal muscle clusters.
Identification of phosphatases on the membranes of guinea pig sperm
Authors: Gordon Mildred , Dandekar Pramila V. , Eager Patricia R.
Published: February 2005

Guinea pig epididymal sperm, incubated for ATPases at pH 7.0 or pH 9.0, localize reaction product on both the periacrosomal segment of the plasmalemma and the outer acrosome membrane. In other species, e.g., rabbit, Ca++‐ATPase is identified with the outer acrosome membrane. It may transport Ca++ into the acrosome for activation of enzymes released during the acrosome reaction. The neutral ATPase is demonstrable on the periacrosomal plasmalem‐ma and possibly modifies Ca++ concentration in the fluid around the acrosome. In guinea pig sperm, Ca++‐ATPase is sensitive to centrifugation or washing of sperm which indicates that the ductal fluid has unusual properties for preservation of the acrosome. Inhibition of the enzyme by these treatments suggests that conditions on the plasmalemmal surface affect the acrosome membrane. Inability to separate reaction product on the plasmalemma from that on the acrosome membrane may be due to migration of reaction product across the periacrosomal space. However, the ATPases are elicited in the guinea pig under the same conditions as in other species. The pH 9.0 enzyme requires Ca++ while the enzyme at pH 7.0 has no ion specificities. Demonstration of these enzymes indicates that mechanisms of acrosome activation, similar to those in other sperm, are relevant to the guinea pig.
Lymphatic vessels of the mammalian heart
Authors: Leak Lee V. , Schannahan Anne , Scully H. , Daggett Willard M.
Published: February 2005

An in situ heart lung preparation was developed to label lymphatics of the actively beating dog heart with subsequent fixation by vascular perfusion. Immediately after interstitial injections of trypan blue and colloidal carbon, a rich plexus of lymphatic vessels was visualized in the epicardium of the actively beating heart. With this method of fixation, tissue preservation is generally excellent and uniform throughout the heart. In thin sections examined with the electron microscope, lymphatic vessels are easily recognized by the content of plasma proteins which is preserved as an electron dense precipitate that is evenly dispersed throughout the lumen. An extensive plexus of thin walled lymphatic vessels is observed throughout the epicardial, myocardial and subendocardial regions. Numerous anchoring filaments are observed closely apposed to the abluminal endothelial surface which extend into the surrounding connective tissue. The distribution and ultrastructure of the cardiac lymphatic vessels are discussed in relation to their role in the removal of interstitial fluid from the heart.
Development of adrenergic innervation of the iris and fluorescent ganglion cells in the choroid of the chick eye
Authors: Kirby Margaret L. , Diab Ihsan M. , Mattio Thomas G.
Published: February 2005

The developing innervation of the chick eye has been studied using catecholamine histofluorescence. The innervation of the pupillary dilator by the superior cervical ganglion begins on day 13 of incubation when fluorescent axons can be seen in the ciliary zone circumscribing the dilator. On day 14 a few processes are seen to branch from this band into the dilator. The number of processes in the dilator increases on days 15 and 16. After day 16 there is a reorganization of the fibers radially accompanied by a moderate increase in the number of processes. In addition, a group of fluorescent cells can be seen in the choroid adjacent to the ciliary body. These cells are bipolar at day 9 and become multipolar by 12 days of incubation. These cells contribute to a fluorescent plexus of processes in the choroid which stops abruptly at the border of the choroid and ciliary zone. It is thought that they represent a terminal sympathetic ganglion receiving preganglionic input from the carotid nerve.
Development of the embryonic chick otic placode. I. Light microscopic analysis
Authors: Meier Stephen
Published: February 2005

At the 7–8 somite stage of embryonic chick development (29‐31 hours of incubation), a slightly elliptical island of thickened ectoderm appears laterally on either side of the most distal constricture of the rhombencephalon at the level of the anterior intestinal portal. The appearance and extent of this auditory placode is precisely correlated with the subjacent accumulation of neural crest cells. By 33 hours of incubation, there is a distinct depression in the developing otic placode, and by 40 to 45 hours, the placode is visibly invaginated, forming an epithelial vesicle or otocyst. Carefully staged embryos were serially sectioned, and the area underlying the developing otic placode was traced with a planimeter. It was found that placode size (area 60,000 μm2) is nearly unchanged from 30 to 42 hours of development. During this time interval, the placode cells first become columnar, show nuclear orientation, and then pseudostratify. The increase in placode cell number during this time interval is not likely to be the result of localized, accelerated cell division: the population doubling time of placode cells is eight and one‐half hours and the mitotic index of 2.5% is similar to that of cells in an equivalent area of adjacent, non‐placode forming head ectoderm. A model of otic placode formation is proposed which suggests that by 30 hours of development, a discrete population of placode forming cells is segregated from head ectoderm. Subsequent epithelial pseudostratification results from accumulation of this dividing population within the limits of the placode.
Maturation of the glomerular visceral epithelium and capillary endothelium in the puppy kidney
Authors: Hay Don A. , Evan Andrew P.
Published: February 2005

The present study describes the development and maturation of the glomerular visceral epithelium and capillary endothelium in an attempt to clarify kidney function in the neonate. The puppy kidney undergoes nephrogenesis for at least two weeks after birth, and thus possesses nephrons of different ages and levels of maturation. Since nephron development varies considerably from inner to outer cortex, renal corpuscles were examined within three arbitrary zones (outer, middle and inner cortex). The visceral epithelium of the smallest glomeruli, i.e., those of the outer cortex, is composed of cuboidal cells which are densely clustered and rests directly upon the limited number of small capillaries. More deeply within the outer cortex, broad, flat epithelial processes extend around the capillary, but lack any visible pedicels. Mid cortical glomerular capillaries undergo an increase in diameter and length, and at the same time the podocytes flatten and separate from one another. Pedicels begin to appear in this zone as thickened, disorganized processes. Juxtamedullary glomeruli are the largest, due primarily to their extensive capillary branching (looping). Podocytes are nearly adult‐like in appearance, with many long primary processes and pedicels.

The endothelial morphology of glomerular capillaries varies from one loop to another, as well as within a single loop. The immature endothelium of outer glomeruli is initially characterized by extensive expanses lacking pores, multiple cellular layers and small, scattered pinholes. Greater capillary maturity is apparent in the mid cortex, due to an increase in pore number and diameter as well as greater attenuation of endothelial cells. However, evidence of remodeling and a lack of pores still exists in some capillaries. The glomerular capillaries of the inner cortex appear the most mature, but possess regions that are still immature when compared to the adult.
The occurrence of uterine stromal and intraepithelial monocytes and heterophils during normal late pregnancy in the rat
Authors: Padykula Helen A. , Tansey Terese R.
Published: February 2005

The steady decline in plasma progesterone level that occurs during the last week of pregnancy in the normal rat (Wiest, '70) provides good opportunity to study the effect of withdrawal of progesterone on uterine differentiation. Evidence is presented that tissue monocytes, heterophils, and eosinophils are regular components of the normal late gestational uterus and that their number increases as term approaches. Uterine monocytes and heterophils are located in the endometrial and myometrial stroma as well as within the basal intercellular compartment of the luminal epithelium. Stromal monocytes are distributed throughout the attenuated endometrium of late gestation, but are more common immediately beneath the luminal epithelium. In the myometrium, monocytes and heterophils occur, often as perivascular clusters, in the connective tissue septum that separates the two layers of smooth muscle. Eosinophils are present especially in the deep endometrial and myometrial stroma, and increase in number as plasma estrogen rises immediately before parturition. A small population of lymphocytes is regularly present.

An important feature of the prepartum uterine stroma is the sparseness of macrophages. Near term, however, the beginnings of monocytic‐macrophagic transformation are noticeable as the cell surface becomes more irregular and organelles associated with endocytic activity arise. The prepartum monocytes are positioned in the same histological sites that during the postpartum period of regression will be occupied by macrophages (Padykula and Campbell, '76). Since it is generally accepted that monocytes are precursors of macrophages, this spatial correlation raises the possibility that cellular preparations for regression commence before birth. The possible significance of prepartum monocytic infiltration is discussed in relation to the effect of changing plasma and uterine concentrations of progesterone on uterine collagenase activity. The steady increase in uterine tissue leucocytes which occurs concomitantly with decreasing uterine binding capacity for progesterone supports the hypothesis by Siiteri et al. ('77) that progesterone in high local concentrations has an antiinflammatory effect.
Scanning electron microscopy of developing photoreceptors in the chick retina
Authors: Olson Mark D.
Published: February 2005

Photoreceptor morphogenesis in the sensory retina of chicks of 2 to 20 days incubation age was studied by scanning electron microscopy (SEM) and correlative transmission electron microscopy (TEM). At 9.5 days spherical inner segments extend into the subretinal space (optic ventricle). They are randomly arranged with chiefly smooth surfaces and contain centrioles, polyribo‐somes and microtubules. Microvilli project primarily from Muller cells. By the twelfth day immature ellipsoid and myoid regions have formed. Microvilli are abundant on the lateral surfaces of inner segments and extend over the entire spherical surface by the fifteenth day. Occasional cilia with surrounding depressions at their bases were also observed. Inner segments are more symmetrically arranged due to close proximity of photoreceptor cells. Inner segments elongate during the sixteenth day; many display a transitional ovoid form. Microvilli become less numerous but some persist as calycal processes. By the eighteenth day, conical shaped outer segments appear. Thereafter, all photoreceptor cells are comparable to those in the mature retina. Abundant microvilli on the external surface of the sensory retina suggest a supportive role in supplying adequate nutrition to the sensory retina during morphogenesis. The establishment and continual development of the ellipsoid and myoid appearto be primarily responsible for the elongation of photoreceptor cells.
Morphometry of tubular bodies in endothelial cells in normal, stable isolated perfused, and edematous dog lungs
Authors: Berendsen Peter B. , Defouw David O.
Published: February 2005

The volume densities and dimensions of tubular bodies (Weibel‐Palade bodies) in dog pulmonary capillary endothelial cells were examined by means of stratified random sampling and electron microscopic morphometry. The mean volume density of tubular bodies in normal (control) lungs was 0.43 ± 0.29%. The mean volume densities of tubular bodies in stable, isolated lungs perfused for 1/2 hour, 1 hour, and 2 hours and in lungs made edematous by increasing hydrostatic pressure or by decreasing oncotic pressure did not vary significantly from that of normal lungs. The mean thickness of the endothelium measured at the middle of the tubular bodies of normal dog lungs was nearly twice the mean thickness of the overall capillary endothelial cell sample. The mean endothelial thickness across tubular bodies from stable and from edematous isolated perfused lungs did not differ significantly from that of the control group. The mean width of tubular bodies from normal dog lungs was 0.25 ± 0.06 μm and the mean length was 0.81 ± 0.61 μm. The mean widths and lengths of tubular bodies from stable and from edematous isolated perfused dog lung endothelial cells did not differ statistically from those of normal dog lungs. Thirty percent of the tubular bodies in the sample were found to be adjacent to a mitochondrion in the same plane of section. Tubular bodies contained both tightly packed and loosely grouped tubules. It is concluded that the tubular bodies in canine pulmonary endothelial cells remain stable during the perfusion of isolated lungs and in oncotic and hydrostatic edema of isolated perfused lungs.
Secretory mechanisms of human ceruminous glands: A transmission and scanning electron microscopic study
Authors: Testa‐Riva Francesca , Puxeddu Paolo
Published: February 2005

Two secretory mechanisms (eccrine and apocrine) were observed by transmission and scanning electron microscopy in the same secretory cells of the human ceruminous glands.

The eccrine secretion occurs as a typical exocytosis by fusion of the limiting membrane of the secretory granule with the apical plasmalemma. The apocrine secretion is more complex and takes place by sequential steps: bulging of the cellular apex into the lumen, constriction of the projection, and detachment of it from the cell. This mechanism generally causes the removal of the entire projection all at once by decapitation at its base; some variations of this process have been found, however, and are described in the present work.

A double membrane, apparently separating the apical protrusion from the rest of the cell, is noticeable in our photographs. Nevertheless, even if this membrane is very similar to a demarcation layer, we consider it as an intercellular double membrane separating two obliquely sectioned cells.
A histochemical analysis of polyanionic compounds found in the extracellular matrix encountered by migrating cephalic neural crest cells
Authors: Bolender David L. , Seliger William G. , Markwald Roger R.
Published: February 2005

Neural crest cells destined to form craniofacial primordia initially are “seeded” into and subsequently migrate through the extracellular matrix (ECM) of a cell free space (CFS) between the surface ectoderm and the underlying mesoderm. Utilizing histochemical procedures for polyanionic compounds, we have demonstrated that both sulfated and nonsulfated glycosaminoglycans (GAG) are present in the CFS of the cephalic region of the chick embryo and that their distribution and structural organization vary with the passage of neural crest or mesodermally derived (MD) mesenchymal cells through it. In stages 7 and 8 embryos a predominance of fine filamentous strands composed primarily of nonsulfated, carboxyl‐rich GAG is seen spanning intercellular spaces between adjacent tissues and MD mesenchymal cells. In older embryos (stages 9 and 10) much of the filamentous material is replaced by coarse fibrillar strands or amorphous material which coats the surfaces of MD mesenchymal and neural crest cells as they invade the CFS. Using enzymatic digestions (Streptomyces and testicular hyaluronidase) and the critical electrolyte concentration procedure, data suggest that the fine filamentous matrix onto which the neural crest cells migrate consists mainly of hyaluronate with lesser amounts of chondroitin and some sulfated GAG present. The coarse fibrillar matrix that appears after passage of either neural crest or MD mesenchymal cells through the original CFS contains strongly sulfated polyanionic material, predominantly chondroitin sulfates A, C. Since GAG is located ubiquitously within the ECM of embryos at various stages, the role of GAG, if any, in the transfer of developmental information may be of a general nature (ie, stimulus of motility) rather than of specific morphogenetic cues (for specific differentiation into craniofacial primordia).
An electromyographic study of the human lateral pterygoid muscles
Authors: Lehr Robert P. , Ownes Stephen E.
Published: February 2005

An electromyographic investigation of the lateral pterygoid muscles was undertaken to determine their activity relative to isolated and functional movements of the mandible. Data was obtained from 14 subjects. Intramuscular fine‐wire electrodes were used bilaterally in the lateral and medial pterygoid muscles. Surface electrodes were placed bilaterally on the skin over the temporalis and masseter muscles.

Our data strongly suggest that separate roles for the superior and inferior heads of the lateral ptyergoid cannot be supported electromyographically. In addition, the lateral pterygoid is active in protrusive movements, including an incisor clench, and not active in retrusion or a molar clench. Both lateral pterygoid muscles initiate depression of the mandible and the contralateral muscle initiates a lateral transversion. The ipsilateral activity present is not sufficient to be an active stabilizer of the temporomandibular joint. In the chewing cycle, the lateral pterygoids are bilaterally active, both in alternation with and overlapping the elevating musculature. The sequence of the lateral pterygoid activity in the chewing cycle is led by the ipsilateral lateral pterygoid muscle.
Rat ovarian mast cells: Distribution and cyclic changes
Authors: Jones Richard E. , Duvall David , Guillette Louis J.
Published: February 2005

Numerous tissue mast cells are present in the ovarian medulla and hilus and in the oviduct of rats. In the medulla, most of these mast cells are in the connective tissue of the stroma near blood and lymphatic vessels. During proestrus, many of the medullary mast cells totally degranulate and thus are not visible histochemically; they then regranulate during estrus. In contrast, the number of stainable mast cells in the ovarian hilus and oviduct does not change during the estrous cycle. Histofluorometric methods demonstrate that mast cells in the ovarian medulla and hilus, as well as the oviduct, contain histamine. In addition, the lining of small blood vessles in the ovarian medulla contains histamine. Thus, mast cell and blood vessel histamine secretion may play a role in ovarian function.
Adaptation of the masseter and temporalis muscles following alteration in length, with or without surgical detachment
Authors: Maxwell Leo C. , Carlson David S. , McNamara James A. , Faulkner John A.
Published: February 2005

Histochemical properties, muscle fiber cross‐sectional area, muscle fiber length, and the oxidative capacity of masticatory muscles of female rhesus monkeys were assessed following alteration in functional length by an intraoral appliance or by detachment of the muscle. Experimental groups received the appliance only (A); the appliance and subsequent detachment of the masseter (AD); the appliance and detached masseter, but with surgical reattachment of the masseter to the pterygomasseteric sling (ADR); no appliance, but detachment and reattachment of masseter (DR); or an appliance which was removed after 24 weeks to study posttreatment responses (PT). Animals were sacrificed and the muscles were studied at intervals from 4 to 48 weeks after initiation of the experimental period. The results of these studies led to the following conclusions: (1) Stretching the masseter and temporalis muscles within physiological limits did not significantly alter the proportion of fiber types, although oxidative capacity of the fibers was reduced. (2) Fibers with “intermediate” myofibrillar AT‐Pase activity were no more prevalent in experimental than control muscles. (3) The cross‐sectional area of Type I fibers of masseter muscles decreased following some experimental procedures, indicating that recruitment of these fibers is the most sensitive to altered jaw function. (4) Minimal alteration of muscle capillarity was induced by any of the experimental procedures. (5) The lengths of masseter muscle fibers in Group PT and of temporalis muscle fibers in groups AD and ADR were greater than in control animals.
Three dimensional arrangement of mitochondria and endoplasmic reticulum in the heart muscle fiber of the rat
Authors: Segretain D. , Rambourg A. , Clermont Y.
Published: February 2005

The three‐dimensional arrangement of mitochondria and endoplasmic reticulum was studied in thick sections of the heart left ventricle fixed in glutaraldehyde and impregnated with the Ur‐Pb‐Cu technique and in thin sections of glutaraldehyde‐fixed tissue post‐fixed in potassium ferrocyanide‐reduced osmium. Squarish flattened mitochondria, approximately the size of a sarcomere, were arranged in longitudinal columns in the clefts between the myofibrils. At the periphery of the fiber, the endoplasmic reticulum took the appearance of a subsarcolemmal network of plate‐like and tubular cisternae running parallel to the cell surface. Between the myofibrils, the ER network formed longitudinally oriented repetitive units whose structure varied according to their position in relation to the A‐ or I‐ bands of the myofibrils. In front of the A‐band, the endoplasmic reticulum appeared as a single layered network of anastomotic tubules compressed between the adjacent myofibrils. In front of the I‐band, it formed a multilayered network the three‐dimensional arrangement of which was dependent upon the presence or absence of the T‐tubule. In the absence of the T‐tubule, the ER cisternae were loosely anastomosed and occasionally displayed bulbous terminal swellings. In the presence of T‐tubules, tubular ER cisternae were seen running parallel on both sides of the T‐tubules and were continuous with sheetlike cisternae sandwiched between the distended T‐tubule and adjacent extremities of longitudinally arranged mitochondria. These tubular or flattened cisternae were connected to each other by numerous bridging cisternae around the T‐tubules.
Tridimensional study of the deep cortex of the rat lymph node. V: Postnatal development of the deep cortex units
Authors: Bélisle C. , Sainte‐Marie G.
Published: February 2005

ABSTRACT Recently, the deep cortex of the adult rat lymph node was shown to be made up of semirounded lymphocytic “units.” Each unit is contiguous to the peripheral cortex, bulges into the medulla, and is centered on the opening(s) of an afferent lymphatic vessel of a node. Furthermore, each unit comprises a “center” and a “periphery,” bearing distinct morphological features. The present study investigated the postnatal development of the units in rats of various ages. One minute after birth, no lymphocytic structures were detected in the nodes. One day after birth, tiny rounded lymphocytic areas were detected in the developing cortex. These areas were topographically related to the openings of afferent lymphatic vessels. One week after birth, small semirounded lymphocytic areas with some morphological features of the adult deep cortex units were observed. Two weeks after birth, typical units were present in the nodes. The observations indicated that the rounded lymphocytic areas observed in nodes of rats aged 1 week or less were actually developing deep cortex units. The overall findings further provided information on the morphological processes involved during the postnatal development of the deep cortex units. Key words: lymph node, deep cortex, development of deep cortex, rat.
Olfactory receptor cell staining using horseradish peroxidase
Authors: Kauer John S.
Published: February 2005

Iontophoretic injection of horseradish peroxidase into severed olfactory nerve fascicles has been used to stain salamander olfactory receptor cell somata, their associated nerves, and their axonal terminations in the glomerular layer of the olfactory bulb. This technique gives homogeneous, Golgi‐like staining of individually identifiable receptor cells and has permitted preliminary mapping of the topographical relationship between the loci of receptors in the olfactory mucosa and sites of their termination in the glomerular layer in the olfactory bulb.
Ultrastructural analyses of control and enzyme‐treated isolated renal basement membranes
Authors: Carlson Edward C. , Meezan Elias , Brendel Klaus , Kenney M. Cristina
Published: February 2005

Glomeruli and tubules were isolated from rabbit kidney cortex by mild homogenization and sieving. Mixtures of these renal components were treated with detergents to prepare pellets of morphologically intact and easily distinguishable tubular (TBM) and glomerular basement membranes (GBM). These BMs were prepared for electron microscopy after: (1) no treatment; (2) treatment with buffer alone; or (3) treatment with enzyme (pronase, trypsin, pepsin, collagenase or testicular hyaluronidase). Mixtures of TBMs and GBMs were treated in the same incubation medium to keep constant the enzyme concentration, temperature, pH, and duration of the treatment. Untreated TBMs showed collapsed, highly folded sheets of electron‐dense material. In contrast, control GBMs were thinner and strikingly resistant to changes in in vivo histoarchitecture. In all enzymatic treatments except hyaluronidase, TBM was more susceptible to digestion than GBM. In general, the effect of pepsin was greater than trypsin, which was greater than pronase. Collagenase also solubilized TBM but was only slightly effective in attacking GBM. Hyaluronidase‐treated BMs were indistinguishable from controls. TBMs and GBMs were both affected least by the enzyme on their epithelial surfaces, which generally remained crisp and sharply demarcated. In contrast, fibrillar materials and BM fragments were released from connective tissue surfaces of TBMs and endothelial‐mesangial surfaces of GBMs. Data in the present study indicate that various BMs are morphologically heterogeneous and that a “non‐unitary” concept of BM is most appropriate. Moreover, the BM “sidedness” demonstrated following enzymatic digestions strongly suggests that macromolecular complexes within laminae densae may be arranged such a manner that opposing surfaces of the same BM are compositionally disparate.
Thymic morphology during in vitro culture
Authors: Eerola E. , Ekfors T. , Tammi R. , Ruuskanen O.
Published: February 2005

Morphology of guinea‐pig thymic fragments was studied sequentially during in vitro organ culture by using light and electron microscopy and 3H‐thymidine autoradiography. In culture the fragments became alymphoid. Thymic lymphocytes started to disappear first at the corticomedullary border, which gradually broadened, giving rise to alymphoid epithelial fragments. As the lymphoid cells disappeared the thymic epithelium began to transform into a keratinized squamous epithelium. The keratinization started in the cells surrounding the Hassall's corpuscles, causing the enlargement of the corpuscles and finally total keratinization of the cultured epithelial fragments. In autoradiographic studies cell proliferation could be observed in uncultured thymuses at the cortical pericapsular area. In cultured alymphoid fragments labelled cells were distributed diffusely in the epithelium. Later labelling was concentrated to epithelial cells transforming to keratinized epithelium. Ultrastructural studies similarly showed transformation of the epithelial cells to squamous keratinized epithelium. The observation support the view that Hassall's corpuscles are derived from the keratinized thymic epithelium and that their existence is connected to the normal function of the epithelium.
Innervation of rat molar teeth: I. Distribution of neuronal cell bodies in the trigeminal ganglion from a mandibular molar tooth
Authors: David Aker F. , Reith Edward J.
Published: February 2005

The cell bodies of neurons innervating a rat mandibular molar tooth were examined with respect to their location in the trigeminal ganglion. The study sought to determine if these cell bodies were restricted to a specific somatotopic location within the mandibular territory of the ganglion or if they were distributed throughout the entire mandibular territory. Horseradish peroxidase (HRP) pellets were placed in the cavity preparation of right first mandibular molar teeth for a 24‐hour period. The animals were then perfusion fixed, and the right trigeminal ganglion was removed, sectioned and processed by the tetramethyl benzidine neurohistochemical technic.

The four trigeminal ganglia constituting this experimental series demonstrated 129, 185, 236, 318 HRP‐positive cell bodies. These cell bodies were dispersed throughout the extent of the mandibular territory. It was concluded from these observations that the distribution of cell bodies innervating a rat mandibular molar tooth is not restricted to a specific region of the mandibular territory of the trigeminal ganglion, but rather the distribution of these cell bodies is throughout all parts of the mandibular territory.
A method of study of the pathology of the conduction system for electrocardiographic and his bundle electrogram correlations
Authors: Lev Maurice , Bharati Saroja
Published: February 2005

There have been advances in electrophysiology which have necessitated a more thorough semi‐quantitative analysis of the entire conduction system to yield data useful for correlation purposes. Thus an attempt is made to modify and expand our previous method of studying the conduction system pathologically. This method thus includes the study of the sinoatrial (SA) node and its approaches, the atrial preferential pathways, the approaches to the atrioventricular (AV) node, the AV node, the penetrating and branching portions of the AV bundle, the bundle branches, the peripheral Purkinje nets, and the remainder of the atrial and ventricular myocardium.

The SA node and its approaches are studied in a longitudinal manner. This gives a better insight into the pathologic changes than does a study in the transverse direction. The approaches to the AV node, bundle and bundle branches are studied in an oblique manner, rather than horizontally apicalward, or from the posterior to the anterior septal region. The horizontal manner does not give sufficient sampling of the AV node and bundle unless complete serial sections are made. Sectioning from the posterior to the anterior septal wall makes difficult an evaluation of the right bundle branch.

In conduction system correlation with Wolff‐Parkinson‐White and Lown‐Ganong‐Levine syndromes complete serial sectioning of both AV rims is advisable. Where complete serial sectioning is impossible in large adult hearts, retaining every fifth section may be permissable. In the study of congenitally abnormal hearts, it is advisable to embed the entire heart as a unit. If that is impossible because of the size of the heart, then very careful judicious planning of the fashioning of the blocks is necessary, so that displaced SA nodes, and anterior AV nodes and bundles are not overlooked.
The internodal atrial myocardium
Authors: Anderson Robert H. , Ho Siew Yen , Smith Audrey , Becker Anton E.
Published: February 2005

The anatomical substrates of internodal conduction have long been a contentious topic. Debated first by the German Pathological Society in 1910, the consensus of established opinion for over half a century was that conduction between sinus and atrioventricular nodes occurred through plain myocardium. This was a conclusion supported by Truex in 1961. Despite his restatement of this fact in 1976, it has become fashionable to describe internodal conduction as being mediated by specialized internodal pathways. To reinvestigate this problem we studied 22 human fetal and 32 human infant hearts. In each case it was possible to cut the atrial tissues as a single block of tissue and to examine serial sections through the internodal myocardium. The sinus node, atrioventricular node, and segments of atrioventricular ring specialized tissue were recognized as specialized tissue using the light microscope in each heart. In contrast, there was nothing “special” about the myocardium between the nodes, nor was it possible to recognize tracts on the basis of either histological appearance or cellular architecture. It is concluded that, from the standpoint of light microscopy, there is no evidence whatsoever to support the purported concept of specialized anatomical substrates for internodal conduction.
Ephemeral, rudimentary glomerular structures in the mesonephros of the mouse
Authors: Zamboni Luciano , Upadhyay Shakti
Published: February 2005

The fine morphology of glomeruli present in the mesonephroi of mouse embryos from days 12 to 14 of gestational age is described. The glomeruli are rudimentary, ephemeral structures which probably result from temporary juxtaposition of a blood capillary to the ventral extremity of a mesonephric tubule. Yet, they might possess a certain degree of functionality.
The fine structure of the placental labyrinth in the sloth, Bradypus tridactylus
Authors: King Barry F. , Pinheiro Paulo B. N. , Hunter Robert L.
Published: February 2005

The placental labyrinth of the three‐toed sloth (Bradypus tridactylus) was examined by electron microscopy. The material available was from two fetuses of 55 mm and 150 mm crown‐rump length (CRL). The placenta of the younger specimen was a transition form between the syndesmochorial type and the endotheliochorial type. The interhemal membrane of the 55 mm CRL specimen consisted of the following components: (1) hypertrophied maternal endothelial cells surrounding the maternal vessels; (2) a small amount of extracellular material and spindle‐shaped cells, both presumed to be of maternal origin; (3) a layer of syncytial trophoblast that had an unusual, reticulated or sponge‐like appearance; and (4) the fetal capillary endothelium. In addition, the fetal connective tissue contained hypertrophied mesenchymal cells that were characterized by abundant granular endoplasmic reticulum. The placenta of the 150 mm CRL fetus was poorly preserved, but it was possible to determine that the placenta was of the endotheliochorial type. There was a close apposition of maternal endothelium and trophoblast. The results confirmed virtually all of the light microscopic observations of Wislocki (1927; 1928b). The ultrastructure of the sloth interhemal membrane is compared to that of other endotheliochorial placentas, particularly that of the shrew, with which it shows many cytological similarities.
The fate of sperm after vasectomy in the hamster
Authors: Flickinger Charles J.
Published: February 2005

Young adult male hamsters were subjected to bilateral vasectomy. The reproductive tracts were studied by light and electron microscopy at intervals up to 1 year after the operation. Sperm continued to be produced, since testicular alterations were focal. Spermatic granulomas were associated with the excurrent ducts of all animals 5 months or 1 year after vasectomy and with those of one of four hamsters 2 weeks after the operation. Phagocytosis of sperm in the lumina of the efferent ducts and proximal parts of the epididymis, and disintegration of membranous components of intraluminal sperm occurred in approximately three‐fourths of the animals studied 5 months or more after vasectomy. The results indicate that after vasectomy in the hamster sperm are disposed of by phagocytosis in spermatic granulomas, intraluminal phagocytosis, and dissolution in the lumen of the male ducts, although the latter process may be incomplete.
Plexus muscularis profundus and associated interstitial cells. I. Light microscopical studies of mouse small intestine
Authors: Rumessen Jüri Johannes , Thuneberg Lars
Published: February 2005

The zinc iodide/osmic acid (ZIO) method was used in a modification that selectively stained nerves and associated interstitial cells of Cajal (ICC ) of muscularis externa. Due to its selectivity the method allowed a detailed stereoscopical analysis of whole mounts with respect to the topography and morphology of these elements. The method thus assisted and expanded our ultrastructural studies. The ZIO staining allowed a distinction of four morphologically different interstitial cell types (ICC‐I‐IV) confined to four compartments. The stained components were: (1) A rich plexus of highly ramified intestitial cells (1CC‐II) in the subserous laver. (2) Auerbach's plexus with an associated extensive plexus of interstitial cells (ICC‐I) in close contact with tertiary fasciculi. (3) Nerve fasciculi of the outer division of the circular muscle layer. These formed a nerve plexus in a well‐defined plane in the outermost cell layers (plexus muscularis super‐ficialis), with few fasciculi located internal to this plexus. A few bipolar interstitial cells (ICC‐IV) were associated with nerve fasciculi of this region. (4) A nerve plexus located in the region between the two subdivisions of the circular muscle, plexus muscularis profundus (PMP). PMP was revealed throughout the small intestine as a continuous network of elongated, circularly oriented meshes. The pattern of connections between PMP and the other enteric plexuses was studied stereoscopically. Ganglion cells intrinsic to PMP occurred widely scattered. Interstitial cells associated with PMP (ICC‐III) were arranged in a plexiform manner; their morphology and relations to nerves were investigated in great detail. A selective innervation of ICC‐III via axons of PMP was strongly supported.
Sequence of ossification in human vertebral neural arch centers
Authors: Ford D. M. , McFadden K. D. , Bagnall K. M.
Published: February 2005

The purpose of the present study is to determine whether ossification of the human vertebral neural arches follows a craniocaudal sequence of development or develops in separate groups from the lower cervical/upper thoracic, upper cervical, and lower thoracic/upper lumbar regions as described by Bagnall et al. (1977b) in a radiographic study.

Seven formalin‐fixed, two fresh frozen, and six serial‐sectioned human embryos and fetuses, ranging in crown‐rump length (C‐R) from 27 mm to 76 mm, were examined. A procedure adapted by Watson (1977a,b) for in toto staining of whole specimens with alcian blue and alizarin red S for cartilage and bone was used, whereas serial sections were stained with hematoxylin and eosin, or Koneff's stain (1960). The intact specimens demonstrated a vivid deep blue cartilaginous skeleton with differentiated red areas of bone development seen through soft tissues rendered transparent by potassium hydroxide or enzyme clearing. The ossification sequence of the neural arches differed from the conventional craniocaudal descriptions given in anatomical textbooks. Neural arch ossification was found to commence in the lower cervical/upper thoracic regions, quickly followed by a second group in the upper cervical region, and subsequently a third group in the lower thoracic/upper lumbar region.
Persistent left hepatic venous connection with the coronary sinus
Authors: Bunger Paul C. , Parke Wesley W.
Published: February 2005

An anomalous direct connection between the left hepatic vein and the coronary sinus in two cadavers is described. The normal development of the central systemic venous system with particular reference to the hepatic region is reviewed and a possible explanation for the present configuration is put forth. Although this configuration of venous anomaly without abnormal shunting of blood is considered clinically insignificant, the association of cardiac arrhythmias with these variations heightens the importance of their identification.
Pulmonary alveolar pores and alveolar macrophage‐mediated particle clearance
Authors: Ferin J.
Published: February 2005

Pulmonary alveolar macrophages (AM) are considered to have an essential role in alveolar clearance of particles. The AM occupy only a small portion of the alveolar surface and their number is probably lower than the number of alveoli. Even at realistic experimental exposures the number of deposited particles, which are distributed all over the lung surface, is orders of magnitude higher than the number of AM. Phagocytosis of deposited particles, however, is being accomplished rapidly within hours. Based on microscopic evidence, we suggest that alveolar pores serve as important passageways for AM by shortening the distance between particles and AM. Accordingly, the pores of Kohn may, in part, lend efficiency to the in vivo particle collection by AM.
Chemotherapy does not affect the development of inter‐sertoli junctions in childhood leukaemia
Authors: Camatini Marina , Franchi Emilia , de Curtis Ivan , Anelli Giuliana , Masera Giuseppe
Published: February 2005

The inter‐Sertoli junctions of children aged between 5 and 12 years, affected by acute lymphoblastic leukaemia, were analyzed in sections and freeze‐fracture replicas. The testicular biopsies were performed at the end of therapy, when patients were in continuous remission for over 30 months. Chemotherapy does not seem to affect the development of junctions that were studied in sections and freeze fracture. Two age groups were considered (I, 5 to 8 years; II, 9 to 12 years). In age group I, oval Sertoli cells were connected by occasionally focal points of fusion, which in replicas appeared as scattered, interrupted ridges on the P face and grooves on the corresponding E face. In age group II Sertoli cells presented cytoplasmic extensions and interdigitations. Tight junctions appeared close to one another in conventional sections. Freeze fracture evidenced extensive although isolated areas formed by intervining strands. Lanthanum penetrated freely the intercellular spaces and gap junctions were observed in both age groups. The results suggest that tight junctions formation is initiated long before puberty; a progression in the complexity of the strand organization is present as the tubules mature; the strands reorganize in parallel and continuous rows only at puberty.