bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology of the lingual apparatus of the domestic chicken, Gallus gallus, with special attention to the structure of the fasciae
Authors: Homberger Dominique G. , Meyers Ron A.
Published: February 2005

A detailed redescription of the mechanically interacting structural elements of the lingual apparatus of the domestic chicken, Gallus gallus, revealed the functional and constructional role of organized connective tissue (i.e., ligaments and fasciae) as structural elements that ensure the proper biomechanical interactions among the various structures within the lingual apparatus (e.g., cartilaginous and bony skeletal elements, muscles, salivary glands, epithelial structures). Fasciae, together with extrinsic muscles, also connect the lingual apparatus to the other components of the feeding apparatus, such as the skull, jaw apparatus, and larynx. For example, the hyoid apparatus is attached to the skull by a sheath‐like fascia (F. vaginalis), the internal structure of which is described here for the first time. Thus, the hyoid suspension in birds differs fundamentally from that in mammals.

This study is the first to examine all biomechanically functioning structural elements that are part of the galliform lingual apparatus in a systematic and comprehensive manner. It also provides a set of novel characters that may be useful for future comparative studies in evolutionary and functional morphology.
Post natal development of the neck system in the chicken (Gallus domesticus)
Authors: Heidweiller Jan
Published: February 2005

The lengths of several neck muscles and tendons and the length, width, and height of the cervical vertebrae and some additional distances were measured in the chicken in six post‐hatching ontogenetic stages and adults. Each vertebra is characterized by a unique combination of growth rates. All increase most in length. Cranial and caudal width as well as height decreases relative to length during ontogeny. When the long dorsal neck muscles are assumed to provide the support for the weight of the head and half of the weight of the neck, the neck system evidently develops according to McMahon's elastic similarity theory. The assumption is justified also because the weights of head and neck together appeared to scale as predicted by elastic similarity. Short neck muscles show negative and tendons positive allometric growth, and long neck muscles grow isometrically relative to neck length. This growth pattern of the muscles and tendons is a direct consequence of the geometric relations of the different growth rates of the vertebrae.
Development of arteriovenous anastomoses in the skin of the chicken and the influence of environmental temperature
Authors: Midtgård Uffe
Published: February 2005

Posthatching differentiation of arteriovenous anastomoses (AVAs) and the effect of heat exposure (38°C) and cold acclimation (2–3°C) on AVA density were studied in naked skin areas (eyelids, comb, wattles) of chickens. The AVAs were identifiable in the newly hatched chick, but they were extremely simple. The number of cell layers in the wall of the AVAs increased from two at hatching to four to five in the 5‐month‐old chickens. The density of the AVAs increased significantly during posthatching maturation. Cold acclimation of the chickens increased the density of AVAs by a factor of 2.1–3.2. Daily heat exposure also increased the density of AVAs significantly in the eyelids but had no effect in the other skin areas. Heat and cold had only minor effect on the vascularity of the skin; the only significant change recorded was a slight increase in the number of blood vessels in the wattles of the cold‐acclimated chickens.
Comparative morphology and morphometry of the nasal fossae of four species of North American shrews (Soricinae)
Authors: Larochelle Renée , Baron Georg
Published: February 2005

The present study compares the morphology of the nasal conchae and the relative development (i.e., surface area and neurosensory cell number) of the olfactory epithelium between four species of shrews occupying different ecotopes (Blarina brevicauda, Sorex cinereus, S. fumeus, S. palustris). The number of olfactory cells was corrected for split cell error. Data were analyzed by using size indices based on the allometric method. The convoluted shape of the maxilloturbinal in Blarina, with large respiratory epithelial surface area, could not be related with certainty to the subterranean ecotope. From the comparison between Soricinae and Crocidurinae, one major difference concerned the shape and attachment of ectoturbinal 3.

Differences in the relative development of the olfactory organ are discussed with regard to differences in the use of chemical signals. The semi‐fossorial B. brevicauda, with the more developed olfactory organ, is reported to possess more scent‐glands and to manifest active scent‐marking behaviors and fecal deposits associated with territoriality. The two terrestrial species, S. cinereus and S. fumeus, have olfactory epithelia showing an intermediate development. Published accounts of fewer scent‐glands and a lack of active scent‐marking behavior indicate a lesser use of olfactory communication in these two species where mutual avoidance seems the rule. Indication of an even more reduced use of olfactory signals in social interactions by the semiaquatic S. palustris is suggested by its least‐developed olfactory epithelium. The comparison between Soricinae and Crocidurinae supports a relationship between the development of the olfactory organ and the relative use of olfactory communication known to occur in social interactions.
Scales in young Polypterus senegalus are elasmoid: New phylogenetic implications
Authors: Sire Jean‐Yves
Published: February 2005

A component of the basal plate which has a plywood‐like organization similar to that of the elasmoid scales of teleosts is described in the scales of Polypterus senegalus for the first time. The origin and development of this structure is studied in young (50–117 mm, standard length) and adult (225 and 240 mm) specimens using light and electron microscopy. In 50 mm fish, the scales are imbricated and composed mainly of a succession of orthogonal collagen layers forming a plywood‐like structure, the isopedin. The outer surface of the scale is ornamented locally by irregular patches of collagenous material. The layers are not mineralized, whereas the superficial patches are well calcified. The isopedin thickens until it has 12–15 layers and then stops growing (88 mm fish). It mineralizes irregularly from its upper part, and two vascular regions, surrounded by woven‐fibered osseous material, form on the outer and deeper surfaces of the isopedin. These regions thicken while the vascular canals close by centripetal deposition of parallel‐fibered osseous tissue. The outer region is the superficial part of the mature scale (called here osteodentin), which is covered by the ganoine deposited by the epidermal cells. The deeper part constitutes the definitive basal plate, composed of parallel‐fibered osseous tissue. The results show (1) that the young ganoid scales of Polypterus senegalus have a structure similar to that of typical elasmoid scales; and (2) that the isopedin structure does not change during ontogeny and so represents a permanent record of the first ontogenetic stages. The phylogenetic implication of these results is that the elasmoid scales of teleosts arose by a process of paedomorphosis.
Osteoclast biology in the osteopetrotic (op) rat
Authors: Marks Sandy C. , Popoff Steven N.
Published: February 2005

Osteopetrosis is a metabolic bone disease characterized by reduced bone resorption. From experimental studies of various osteopetrotic mutations has emerged the hypothesis that each is unique with respect to mechanisms whereby osteoclast development and/or function are reduced. The osteopetrotic (op) mutation in the rat was discovered in Fatty/ORL stock over a decade ago. The paucity of data about osteoclast biology in this mutation prompted this study of cytological, cytochemical, and ultrastructural features of osteoclasts. In op rats, osteoclasts are significantly reduced in number, but are larger and more vacuolated than in normal littermates. Mutant osteoclasts can form ruffled borders and clear zones, but their ability to fragment and excavate bone surfaces is greatly impaired. Cytoplasmic vacuoles in op osteoclasts are randomly distributed and greatly enlarged, and they stain weakly for two cytochemical characteristics of osteoclasts, tartrate‐resistant acid phosphatase and acid ATPase. These findings suggest that an abnormality in the lysosomal/vacuolar system, an important component of the resorptive mechanism, may be involved in the interception of osteoclast function in this mutation.
Eosinophils and mast cell homogeneity of the guinea pig eyelid skin, conjunctiva, and ileum
Authors: Stock E. Lee , Hill Richard A. , Boyle‐Vavra Susan , Roth Sanford I.
Published: February 2005

Mast cell heterogeneity has been described on the basis of differential staining reactions, light microscopic morphology, anatomic location, degranulation after polyamines, biochemical contents, growth requirements, and reactions to lymphokines. We have demonstrated typical “connective‐tissue mast cells” by using anatomic criteria, histological staining reactions, electron microscopy, and reaction to compound 48/80 in the guinea pig conjunctiva, eyelid skin, and ileum. A second, much larger population of cells in the ileal mucosa and the conjunctiva, and rarely in the eyelid skin stained reddish‐blue with acid toluidine blue in tissue fixed in ethanol‐acetate‐lead subacetate (BLA) and with alkaline Giemsa in formaldehyde‐fixed tissue, did not stain with ethanolic or acid toluidine blue in formaldehyde‐fixed tissue or with alkaline Giemsa in BLA‐fixed tissue, and did not degranulate after 48/80 treatment. These are features of the rat intestinal “mucosal mast cells”; however, ultrastructural and light microscopic studies with the orcein Giemsa stain demonstrated these cells in the guinea pig to be eosinophils. Tissue culture, biochemical, and immunological studies indicate the existence of a second type of mast cell (bone‐marrow‐derived mast cell), ultrastructurally almost indistinguishable from the connective tissue mast cell. Our studies demonstrate only one mast cell type in the guinea pig and support the contention that other forms of mast cells are immature forms or variants of the connective‐tissue mast cell.
Postnatal development of vascularity in the inferior colliculus of the young rat
Authors: Andrew D. L. E. , Paterson J. A.
Published: February 2005

The inferior colliculus in the rat midbrain is an auditory relay center whose functional maturation occurs postnatally. We examined by morphometry the vascularity and the nuclear profile density of the inferior colliculus in normal young rats at different ages (before and after the onset of auditory input). We also compared this region with a frontal region of the cerebral cortex in 24‐day‐old rats. The inferior colliculus from aldehyde‐perfused Sprague‐Dawley rats aged 5, 9, 14, and 24 days was analyzed by light microscopy of semithin plastic sections. The central region (mostly the central nucleus) was sampled at 5 levels representing its entire rostrocaudal extent. Patent‐blood‐vessel profiles were counted and classified according to their size and profile orientation. Counts of nuclear profiles in the same sections were also made. In the inferior colliculus of rats between 5 and 24 days of age, the small (>10‐μm diameter) cross‐sectioned vessel profiles increased over 6‐fold in number per unit area. Correspondingly the vascular volume density, estimated by differential point counting, increased between these ages. However, there was a decrease in the number of neuronal and glial nuclear profiles per unit area, probably because of growth in the volume of the neuronal perikarya and processes, along with cell emigration reported to occur at early postnatal ages. This study has shown that an increase in vascularity in the central region of the rat inferior colliculus continues for up to 2 weeks after the onset of hearing. The numerical density of small vessels in the rat inferior colliculus had reached the adult level of vascularity by 24 days of age. Also, by 24 days and possibly earlier, regional differences in capillary density in the brain were evident; the frontal cortex was found to have fewer small vessel profiles per unit area and a lesser vascular volume density than the inferior colliculus. Thus, such micro‐regional differences in vascularity must have arisen earlier during brain and capillary growth.
Distribution of endogenous albumin across the rat aortic wall as revealed by quantitative immunocytochemistry
Authors: Londoño Irene , Bendayan Moise
Published: February 2005

Endogenous albumin was revealed over thin sections of rat aortic wall, with high resolution and specificity, by applying the protein A–gold immunocytochemical technique. Gold particles, revealing albumin antigenic sites, were observed over plasmalemmal vesicles in endothelial cells and over the interstitial space throughout the thickness of the aortic wall. The distribution of the labeling in the interstitial space varied from region to region and was associated with the collagen fibers, following the orientation of the bundles. The morphometric evaluation of this labeling demonstrated a first peak in labeling intensity in the intima followed by a steep decrease with low levels in the media, and an increasing gradient towards the adventitia. In the subendothelium, a moderate labeling was observed at the base of the endothelial cells of both aortic and capillary endothelia, followed by a decreasing gradient. Ratios between the labeling density in the intima as well as in the adventitia and that in the capillary lumen (plasma albumin) revealed different concentrations of albumin in these compartments. Endogenous albumin, under steady‐state conditions, is thus unevenly distributed over the interstitial spaces across the rat aortic wall, and appears associated along the collagen fibers.
Diameter increase of collagen fibrils of the mouse endometrium during decidualization
Authors: Alberto‐Rincon Maria C. , Zorn Telma M. T. , Abrahamsohn P. A.
Published: February 2005

The diameter of collagen fibrils was measured in different regions of the antimesometrial endometrium of mice on days 5, 6, and 7 of pregnancy as well as in the endometrium of virgin mice. The average diameter of fibrils of virgin mice was 39.18 nm (range: 20–80). In the region of fully decidualized cells, the averages and ranges were 45.32 nm (30–170), 89.39 nm (30–270), and 125.88 nm (20–370), respectively, on days 5, 6, and 7 of pregnancy. Thick fibrils larger than 70 nm had irregular profiles. Our results show that the increase in diameter is associated with the decidualization of the mouse endometrium.
Differentiation of cyclophosphamide‐treated hamster secondary palate: Ultrastructural and biochemical observations
Authors: Shah Ravindra M.
Published: February 2005

A study was undertaken to analyze the ultrastructural aspects and the enzyme acid phosphatase cytochemistry and biochemistry of the pathogenesis of cyclophosphamide (CP)‐induced cleft palate in hamster fetuses. The initial CP‐induced alterations were the appearance of lysosomes in the mesenchymal cells of the vertically developing palatal primordia within 8 hr of drug administration. The mesenchymal lysosomal activity, which increased during the next 16 hr, was abnormal and interpreted as a sub‐lethal response to CP treatment. Subsequently, the lysosomal activity in the mesenchyme diminished gradually and, 48 hr after CP treatment, was absent. At this time, lysosomes were seen in the epithelial cells of the vertical palate. Fifty‐six hours after CP treatment, unlike controls where palatal shelves were already fused, lysosomal activity subsided in the epithelial cells. Changes, however, continued to be seen at the epithelial‐mesenchymal interface. These changes were characterized by discontinuity in the basal lamina, and by epithelial‐mesenchymal contacts. They persisted for 8 hr but were absent thereafter. Sixty‐four hours after CP administration, the vertical shelves became horizontal and remained so until term. Following analysis of data, both from the literature and from the present study, it was suggested that CP first affected mesenchymal cell proliferation, and then its cytodifferentiation, during the critical phase of early vertical development; consequently the reorientation of the shelves to a horizontal plane was delayed, inducing celft palate.
Prenatal development of “synaptic” ribbons in the guinea pig pineal gland
Authors: Luo Z. R. , Schultz R. L. , Whitter E. F. , Vollrath L.
Published: February 2005

Pineal “synaptic” ribbons are a heterogeneous population of organelles. “Synaptic” ribbons (SR) sensu stricto, “synaptic” spherules (SS), and intermediate forms (IMF) are present. Their function and origin are unknown, and a knowledge of their prenatal development is lacking. Thus the pineal glands of prenatal, neonatal, and adult guinea pigs were prepared for electron microscopy. “Synaptic” ribbons were studied morphologically and quantitatively. The three categories of “synaptic” ribbons reported in adult pineal glands were also present in prenatal pineal glands. Their structural features, distribution, grouping, and composition patterns are similar to those in adults. “Synaptic” ribbons were first detected in pinealocytes of the distal region of a 42‐day postcoitus (PC) pineal gland and were comparable with those in adults. They increased in number with age and reached a peak at 63 days PC, followed by a steep decline at 66 and 67 days PC. By day 69 PC, the numbers increased again and showed a dramatic increase after birth. Several true ribbon synapses were seen at day 63 PC between pinealocyte cell processes or between pinealocyte cell process and pinealocyte cell body. Since true ribbon synapses have not been found in adult guinea pig pinealocytes, their synaptic nature could have been lost during development. No precursors for the “synaptic” ribbons were found. The endoplasmic reticulum cisternae may be the origin for the ribbon vesicles because of their close association with the “synaptic” ribbons.
Peripheral development of avian trigeminal nerves
Authors: Kuratani Shigeru , Tanaka Shigenori
Published: February 2005

Development of the trigeminal nerve branches was studied in stage ‐17 to ‐27 chick embryos stained with an antibody to neurofilament protein. The following findings were obtained. (1) Ectopic ganglia transiently appeared in the ectoderm of the supraorbital region and were considered as remnant ophthalmic‐placode‐derived ganglia. (2) Most of the cutaneous sensory branches of the maxillomandibular nerve arose from a loosely arborized mass of neurites, provisionally termed the maxillomandibular reticulum, in which the fibers intermingled in a seemingly random fashion. (3) The growth of the trigeminal branches was mainly correlated with the development of the facial processes; however, irregular communications between different groups of branches were observed, suggesting that topographical organization of the peripheral branches is not rigid in early stages. (4) From the ophthalmic nerve around stage 23, transient dorsal rami developed and were distributed in the mesenchymal space, the cavum epiptericum, and passed near the ectoderm. Their homology with the rr. tentorii in human anatomy is suggested.
Ontogenetic development of the ophthalmic rete in relation to brain cooling in chickens and pigeons
Authors: Arad Zeev , Midtgard Uffe
Published: February 2005

The brain cooling capacity of the altricial pigeon increases during posthatching growth at a higher rate than that of the precocial duck and chicken. To determine if this difference between the altricial and the precocial modes of development can be related to growth rates of the vascular heat exchanger involved in brain cooling (the ophthalmic rete), we performed a morphometric analysis of this structure during the posthatching maturation of the three species. The number of vascular units in the rete did not change during development but differed significantly among species. The retia continued to grow in length and diameter in an exponential relation with body mass at similar rates in all species. The surface area of the retial arteries, which reflects the area available for countercurrent heat exchange, also increased exponentially with body mass, but without significant differences among the three species. However, the effectiveness of the rete in brain cooling, as indicated by the degree of brain cooling per unit of heat‐exchange area in the rete, was higher in the altricial pigeon than in the precocial chicken and duck. It is concluded that the posthatching morphometric changes in the ophthalmic rete (rete ophthalmicum) are important for the development of brain cooling capacity, but cannot solely explain differences in brain cooling between growing altricial and precocial birds. These differences are most likely related to differences in the maturation of the central thermoregulatory control system and the peripheral effector mechanisms among the two groups of birds.
Deep splenic lymphatic vessels in the mouse: A route of splenic exit for recirculating lymphocytes
Authors: Pellas Theodore C. , Weiss Leon
Published: February 2005

A study of pathways of lymphocyte migration through mouse spleen revealed lymphatic channels closely following arteries in trabeculae and white pulp. Because there is no detailed record of the layout of deep splenic lymphatics in the mouse, or other species, we present our observations in this paper, relating our findings to normal migratory pathways of lymphocytes through the spleen. Lymphatics draining the spleen are so inconspicuous that they often are not mentioned in anatomical discussions. The data presented clearly demonstrate (1) the existence and layout of deep lymphatic vessels in the mouse spleen, and (2) that migrating lymphocytes exit white pulp via these lymphatic vessels.

CD4+ and CD8+ T cell subsets migrated proximally along the central artery from distal (dPALS) to proximal periarterial lymphatic sheaths (pPALS) and exited via deep lymphatic vessels that originate there. B cells migrated from dPALS to enter lymphatic nodules (NOD), thus segregated from T cells. B cells then migrated toward and exited via deep lymphatics. The appearance of labelled lymphocytes in lymph coincided with their disappearance from white pulp compart‐ments. Labelled T cells were observed in splenic lymphatics as early as 1 hr after intravenous infusion but took, on average, about 6 hr. B cells took somewhat longer. Thus T and B cells entered and left white pulp through shared pathways, but took divergent intermediate routes through dedicated zones, pPALS for T cells, NOD for B cells.
Development and innervation of the abdominal muscle in embryonic Xenopus laevis
Authors: Lynch Kathryn
Published: February 2005

The morphogenesis and innervation of the ventral abdominal musculature in Xenopus embryos was examined using microscopic techniques. Muscle development begins at Nieuwkoop and Faber Stage 31, when aggregates of undifferentiated cells form on the ventrolateral margins of rostral trunk myotomes. During subsequent stages, aggregates form and detach from progressively more caudal myotomes to form a series of seven discrete cell clusters (anlagen). The anlagen migrate ventrally in a cell‐free space between the epidermis and a subepidermal layer of pigment cells. Extracellular aggregates of 30‐nm granules are evident transiently between the migrating anlagen and the epidermis. During stages 39 and 40, each anlage transforms into a sheet of myotubes which attaches rostrally and caudally to adjacent sheets to form a seven‐segmented muscle. The series of broad segments, approximately one fiber thick, extends from the pericardium to the level of the proctodeum. The embryonic muscle is innervated by the ventral rami of spinal nerves 2 to 9. The major nerve trunks to the muscle develop between stages 35/36 and 40. Axons initially grow ventrally along the paths taken by the muscle anlagen. When the anlagan become muscle segments, the nerves are deep to the narrow boundaries between the segments. Spinal nerve 2 ramifies in the first muscle segment and sends fibers rostrally to the geniohyoid muscle. The findings represent the first description of the development of this muscle in Xenopus and the first account of the development of the abdominal motor nerves in an amphibian embryo.
Development of the dentition in Alligator mississippiensis: Upper jaw dental and craniofacial development in embryos, hatchlings, and young juveniles, with a comparison to lower jaw development
Authors: Westergaard Bjarne , Ferguson Mark W. J.
Published: February 2005

Development of the upper dentition in Alligator mississippiensis as investigated using a close series of accurately staged and aged embryos, hatchlings, and young juveniles up to 11 days posthatching, as well as some young and old adult specimens. Studies from scanning electron miscroscopy, light microscopy, acetate and computer reconstructions, radiography and macroscopy were combined to elucidate the details of embryonic dental development, tooth initiation pattern, dentitional growth, and erupted functional dentition. The results were compared with those from the lower jaw and related to the development of other craniofacial structures.

Approximately 17 early teeth in each jaw half develop as surface teeth, of which 13 project for 1 to 12 days before sinking into the mesenchyme. The first three teeth initiate directly from the oral epithelium at Ferguson stages 14–15 (days 15–19 after egg laying), before there is any local trace of dental lamina formation. All other teeth develop from a dental prolamina or lamina; and with progressive lamina development, submerged teeth initiate from the aboral end leading to the formation of replacement teeth. All teeth form dentin matrix, but 12 early teeth do not form enamel. Approximately 20 embryonic teeth are resorbed, 6 are transitional, and 42 function for longer periods after hatching.

The embryonic tooth initiation pattern (illustrated by defining a tooth position formula) does not support the previous models of Odontostichi, Zahnreihen, and Tooth Families, each of which postulates perfect regularity. Up to three interstitial tooth positions develop between sites of primary tooth initiation, and families with up to five generations at hatching are at first arbitrarily defined.
Cell‐cell interactions in the control of spermatogenesis as studied using leydig cell destruction and testosterone replacement
Authors: Sharpe R. M. , Maddocks S. , Kerr J. B.
Published: February 2005

This review centers around studies which have used ethane dimethane sulphonate (EDS) selectively to destroy all of the Leydig cells in the adult rat testis. With additional manipulations such as testosterone replacement and/or experimental induction of severe seminiferous tubule damage in EDS‐injected rats, the following questions have been addressed: (1) What are the roles and relative importance of testosterone and other non‐androgenic Leydig cell products in normal spermatogenesis and testicular function in general? (2) What are the factors controlling Leydig cell proliferation and maturation? (3) Is it the Leydig cells or the seminiferous tubules (or both) which control the testicular vasculature?

The findings emphasize that in the normal adult rat testis there is a complex interaction between the Leydig cells, the Sertoli (and/or peritubular) cells, the germ cells, and the vasculature, and that testosterone, but not other Leydig cell products, plays a central role in many of these interactions. The Leydig cells drive spermatogenesis via the secretion of testosterone which acts on the Sertoli and/or peritubular cells to create an environment which enables normal progression of germ cells through stage VII of the spermatogenic cycle. In addition, testosterone is involved in the control of the vasculature, and hence the formation of testicular interstitial fluid, presumably again via effects on the Sertoli and/or peritubular cells. When Leydig cells regenerate and mature after their destruction by EDS, it can be shown that both the rate and the location of regenerating Leydig cells is determined by an interplay between endocrine (LH and perhaps FSH) and paracrine factors; the latter emanate from the seminiferous tubules and are determined by the germ cell complement. Taken together with other data on the paracrine control of Leydig cell testosterone secretion by the seminiferous tubules, these findings demonstrate that the functions of all of the cell types in the testis are interwoven in a highly organized manner. This has considerable implications with regard to the concentration of research effort on in vitro studies of the testis, and is discussed together with the need for a multidisciplinary approach if the complex control of spermatogenesis is ever to be properly understood.
A comparative study in twelve mammalian species of volume densities, volumes, and numerical densities of selected testis components, emphasizing those related to the sertoli cell
Authors: Russell Lonnie D. , Ren Hong Ping , Hikim Indrani Sinha , Schulze Wolfgang , Hikim Amiya P. Sinha
Published: February 2005

Morphometric studies were performed on 12 mammalian species (degu, dog, guinea pig, hamster, human, monkey, mouse, opossum, rabbit, rat, stallion, and woodchuck) to determine volume density percentage (Vv%), volume (V), and numerical density (Nv) of seminiferous tubule components, especially those related to the Sertoli cell, and to make species comparisons. For most species, measurements were taken both from stages where elongate spermatids were deeply embedded within the Sertoli cell and from stages near sperm release where elongate spermatids were in shallow crypts within the Sertoli cell. Montages, prepared from electron micrographs, were used to determine Vv% of Sertoli cell components in seminiferous tubules. Excluding the tubular lumen, the Sertoli cell occupied from a high of 43.1% (woodchuck) to a low of 14.0% (mouse) of the tubular epithelium. There was a strong negative correlation (r =−0.83; P<0.005) of volume occupancy of Sertoli cells with sperm production. Nuclear volume, as determined by serial reconstruction using serial thick sections, ranged from a high of 848.4 μm3 (opossum) to a low of 273.8 μ3 (degu). There was no correlation (r=0.02) of nuclear volume with volume occupancy (Vv%) in the tubule. Sertoli cell volume was determined by point‐counting morphometry at the electron‐microscope level as the product of the nuclear size and points determined over the entire cell divided by points over the nucleus. Sertoli cell V ranged from 2,035.3 μm3 (degu) to 7,011.6 μm3 (opossum) and was highly correlated (r=0.85; P<0.001) with nuclear size. However, there was no significant correlation between the Sertoli cell size (V) and volume occupancy (Vv%; r = 0.13) or sperm production (r = 0.21). Stereological estimates of the numerical density (Nv) of Sertoli cells ranged from a high of 101.9 × 106 (monkey) to a low of 24.9 × 106 (rabbit) cells per cm3 of testicular tissue. There was no correlation of numerical density of Sertoli cells with sperm production (r=0.002). A negative correlation was, however, observed between the numerical density of the Sertoli cells and the Sertoli cell size (r=−0.79; P<0.002). Data from the present study are compared with those previously published. This is the first study to compare Sertoli cell morphological measurements using unbiased sampling techniques. Morphometric data are provided which will serve as a basis for other morphometric studies.
Distribution of sodium‐potassium ATPase in the rat testis and epididymis
Authors: Byers Stephen , Graham Robert
Published: February 2005

Sodium‐potassium ATPase (Na+ K+‐ATPase) is a ubiquitous plasma membrane enzyme which uses the hydrolysis of ATP to regulate cellular Na+ and K+ levels and fluid volume. This ion pumping action is also thought to be involved in fluid movement across certain epithelia. There are several different genes for this enzyme, some of which are tissue specific. Using an antibody specific for the catalytic subunit of canine kidney Na+ K+‐ATPase, we have localized immunoreactivity in the seminiferous and epididymal epithelium of rats of various ages. There was no specific staining of 10‐day‐old rat testis. Faint staining was detected at 13 days and appeared to be associated with the borders of Sertoli cells. At 16 days prominent apical and lateral staining but no basal staining of Sertoli cell membranes was observed. This type of distribution continued until spermatids were present in the epithelium. In the adult rat testis, specific staining was detected in Sertoli cell crypts associated with elongating spermatids, and on the apical and lateral Sertoli cell membrane. In some instances immunoreactivity was concentrated at presumed sites of junctional specializations. In the excurrent ducts of immature and mature rats, Na+ K+‐ATPase staining was heavy in the efferent ducts and somewhat lighter in the epididymis. In all regions, the staining was basolateral although there were variations in intensity among the different parts of the epididymis. These results show (1) that rat testis and epididymal Na+ K+‐ATPase share some immunological determinants with the canine enzyme; (2) that the epididymal enzyme is located in the conventional basolateral position; and (3) that the distribution of Sertoli cell Na+ K+‐ATPase is probably apical and lateral rather than basal.
Immunofluorescence localization of vinculin in ectoplasmic (“junctional”) specializations of rat sertoli cells
Authors: Grove B. D. , Pfeiffer D. C. , Allen S. , Vogl A. W.
Published: February 2005

We have investigated, using indirect immunofluorescence techniques, the possibility that vinculin is a component of Sertoli cell ectoplasmic specializations. Affinity‐purified polyclonal antibodies produced against human platelet vinculin were used to probe fixed frozen sections of rat testis. Specific fluorescence occurs in Sertoli cell regions adjacent to spermatids and to basally situated junctional complexes, sites at which ectoplasmic specializations are known to occur. Staining also occurs in Sertoli cell regions associated with tubulobulbar complexes. The antibody also labels focal contacts in cultured human dermal fibroblasts, apical junctional sites of rat epididymal epithelium, and dense plaques of smooth muscle. Our results are consistent with the prediction that vinculin is likely a component of ectoplasmic specializations and are also consistent with the hypothesis that these structures are a form of actin‐associated adhesion complex.
A novel perspective: The occluding zonule encircles the apex of the sertoli cell as observed in birds
Authors: Pelletier R‐Marc
Published: February 2005

The modulation of Sertoli cell junctions was studied in the non‐seasonal rooster (Gallus domesticus) and in the seasonally breeding mallard duck (Anas platyrynchos anatidae) using thin sectioning, a junction permeability tracer, and freeze‐fracture replication. During the active spermatogenic phase, the junctions of the duck appeared similar to those of the rooster, therby establishing the duck as an avian model of seasonal modulation of Sertoli cell junctions. As with mammalian seasonal breeders, during the active phase, occluding, gap, and adhering junctions formed a junctional complex all along the long axis of the Sertoli cell. Unlike in mammals, however, no 7‐nm filaments were associated with the occluding junctions. An occluding zonule encircled the Sertoli cell apico‐lateral membrane domain situated above the young germ cells, and constituted a barrier to the entry of lanthanum in the basal third of the seminiferous epithelium. Toward the basal side, forming focal junctions were located on the lateral Sertoli cell membrane domain facing the young germ cells. Toward the apical side, dismantling focal junctions were located on the apical Sertoli cell membrane domain facing the older germ cells.

During the duck's testicular regression, 7‐nm filaments were associated with an occluding junction. In freeze‐fracture replicas, each junction was formed by a continuous junctional strand that encircled the apex of the cell. The strands composed a delicate narrow meshwork: an occluding zonule. The blood‐testis barrier was localized near the apex of the epithelium. The seasonal reduction in the number of the strands and the changes in their orientation did not coincide with a change in the permeability of the occluding zonule to lanthanum. In addition, the cyclic disappearance of junction‐associated filaments was not correlated with a change in the permeability of the junctions but with a change in the affinity of junctional particles for one or the other fracture face. It is proposed that the Sertoli cell plasma membrane domains situated apical and basal with respect to the occluding zonule be considered apical and lateral, respectively. The remaining domain facing the basement membrane would therefore be called basal. In the duck, the occluding zonule is not seasonally shifted from the base to the apex of the Sertoli cell. Instead, it remains stationed above the younger germ cells throughout the year. The illusory shift in the location of the blood‐testis barrier during the active phase actually results from the formidable expansion of the Sertoli cell apical membrane domain above the occluding zonule to accommodate the development of germ cells. It follows that the occluding zonules forming the blood‐testis barrier in the nonseasonal breeders actually encircle the apices of the Sertoli cells although they occur in the basal third of the seminiferous epithelium.
Connective‐tissue macromolecules in Golgi chicken tendon organs and at their interface with muscle fibers and adjoining tendinous structures
Authors: Maier Alfred , Mayne Richard
Published: February 2005

Tendon organs from leg and forearm muscles of white leghorn chickens were examined with a library of monoclonal antibodies to determine the composition of their connective‐tissue framework and the types of connective‐tissue macromolecules that occur at the sites where muscle fibers attach to the receptors. The capsules of the tendon organs were positive for connective‐tissue macromolecules typical of basal lamina (collagen type IV, laminin, and heparin sulfate proteoglycan) and for tenascin, collagen types III and VI, and fibronectin. Connective‐tissue bundles in the lumen of a receptor reacted primarily with antibodies against collagen type I and 4‐chondroitin sulfate. The narrow partitions that divide each lumen into compartments stained for collagen type III. Toward its tendinous end, a receptor made few contacts with muscle fibers. Instead, the capsule and the collagenous bundles blended gradually with the intermuscular portions of tendons. At the muscular end, the connections were more complex. Muscle fibers that attached in series to tendon organs split to produce basal lamina‐covered, finger‐like extensions, which were separated from each other by fissures. Tongues of connective tissue containing tenascin, collagen types I and VI, and fibronectin extended into the fissures. Distally the tongues were continuous with the tenascin in the capsule and just internal to the capsule, fibronectin and basal lamina macromolecules in the capsule, and collagen type I in the collagenous bundles. The uninterrupted presence of these macromolecules around terminating muscle fibers and in the capsule and/or the intraluminal collagen bundles suggests that muscle fibers that attach in series at the muscular end exert a force during muscular contraction on the intraluminal collagen bundles and on the receptor capsule.
Comparative anatomical studies of thyroid and thymic arteries: I. Rat (Rattus norvegicus albinus)
Authors: Yamasaki Masahiro
Published: February 2005

The thyroid and thymic arteries were investigated in 50 male and 50 female rats. In more than 70% of the animals, on both sides the cranial thyroid artery forms a common trunk with the ascending pharyngeal artery. The caudal thyroid artery arises not from the deep cervical but from the pericardiacophrenic artery. It may be replaced, however, by a branch of some other artery, such as the brachiocephalic, subclavian, vertebral, or ascending cervical, suggesting a shift of its origin from the internal thoracic artery to the thyrocervical trunk as in man. All the thoracic lobes of the thymus are supplied directly by a thymic branch of the internal thoracic artery or indirectly by a branch of the pericardiacophrenic artery. More than half of the specimens have a cervical thymic lobe of variable size, which is supplied by a branch of the cranial thyroid, external carotid, and/or occipital arteries. Some of these thymic arteries, except those from the external carotid and occipital arteries, reach the thoracic lobe. The thoracic lobes lacking a cervical lobe may be supplied by the thymic branch arising only from the cranial thyroid artery. Other anomalous arteries supplying the thoracic lobe are derived from the superficial cervical and/or the right common carotid arteries. These results show that the thymic arteries of rats are basically similar to those of man, although they display a clear difference in their frequency and origin.
Giant mitochondria distinct from enlarged mitochondria in secretory and ciliated cells of gerbil trachea and bronchioles
Authors: Spicer S. S. , Parmley R. T. , Boyd L. , Schulte B. A.
Published: February 2005

Numerous mitochondria ranging from slightly larger than normal to several micrometers in diameter (giant) were found in about one‐half the serous secretory cells in the surface epithelium of the normal gerbil trachea and proximal bronchi. Tracheal serous cells of mice also were found to contain numerous giant mitochondria. Clara cells of gerbil bronchioles contained abundant giant mitochondria in addition to normal tubular mitochondria and the second population of enlarged spherical mitochondria that have been described in Clara cells of several genera. In contrast, mouse Clara cells revealed the normal tubular and the enlarged spherical mitochondria but no giant mitochondria. A survey of a number of cell types in gerbils failed to disclose hypertrophied mitochondria outside tracheobronchial surface epithelium and bronchioles. The mitochondrial enlargement resulted from an increase of matrix but not cristae. The expansion of matrix displaced the relatively sparse cristae into small collections compressed against the outer membrane. The prevalence of giant mitochondria and of granular endoplasmic reticulum is similar among cells, and these two organelles are codistributed within cells. The megamitochondria and granular reticulum occupy a central stratum, whereas normal mitochondria occur in the apical and basal regions. The giant mitochondria are considered related to a normal biologic activity that is characteristic of respiratory tract epithelium of mice and gerbils selectively and is more prominent in secretory cells than in ciliated cells.
Development of the vasculature of the pars distalis in a tumor‐susceptible strain of rat (Fischer 344) differs from vascular development in a non‐tumor‐susceptible strain (Lewis)
Authors: Schechter Joel E.
Published: February 2005

The development of the vasculature of the pars distalis of two strains of rat, Fischer 344 (F344) and Lewis (LEW), was followed in 16‐day (16d) and 20‐day (20d) fetuses, and in 1‐day (1d), 5d, 20d, 50d, and 6‐month‐old females. No differences in the two strains were apparent in 16d fetuses; and the capillaries that were present were immature, i.e., tall, non‐fenestrated endothelial cells, and were surrounded by poorly delineated pericapillary spaces. Immature capillaries also were predominant in 20d fetuses of both strains. Agranular folliculo‐stellate cells were identifiable, projecting endfeet to the parenchymal basal lamina in 20d F344 fetuses, but not in LEW fetuses.

Postnatally, the capillaries of LEW rats became progressively more thin‐walled and fenestrated, and were surrounded by a pericapillary space that was well delimited by basal laminae at 20d. In 50d and 6‐month LEW rats, capillaries were intact and surrounded by well‐defined pericapillary spaces. By comparison in F344 rats, the capillaries remained more immature even in 50d rats and older. In addition, in F344 rats focal disruptions in endothelial cells and disruptions in parenchymal and capillary basal laminae were present in all postnatal stages, and a dramatic accumulation of plasma was evident within the pericapillary spaces at 20d. Endfeet processes of folliculo‐stellate cells were abundant at the parenchymal basal lamina of 1d and 5d F344 neonates, but only rarely were identified in LEW neonates. Some activation of folliculo‐stellate cells, i.e., increased numbers of lysosomes and dilated endoplasmic reticulum, was present in 50d F344 rats. Connective‐tissue cells within the pericapillary space also were numerous and activated in F344 rats. Discrete gaps in the parenchymal basal lamina were evident subjacent to the folliculo‐stellate cell endfeet in F344 rats but not in LEW rats.

The vascular bed of F344 rats differs in its development from that of LEW rats. Characteristic of the F344 strain is a persistence of more immature capillaries, an inherent vascular fragility, and an activated state of folliculo‐stellate cells.
Macrophage mobilization and morphology during lens regeneration from the iris epithelium in newts: Studies with correlated scanning and transmission electron microscopy
Authors: Reyer Randall W.
Published: February 2005

The lens was removed from both eyes of adult newts (Notophthalmus viridescens), and the eyes were fixed in Karnovsky's fixative every 2 days 0–20 days after operation. Anterior half‐eyes were prepared by standard procedures for scanning electron microscopy of the surface. Before fixation, the posterior iris surface was cleaned of adhering vitreous mechanically with forceps or by treatment with bovine testicular hyaluronidase or with hyaluronidase and collagenase. Some specimens were cryofractured in buffer or ethanol transverse to the mid‐dorsal iris, and the fractured surface viewed with scanning electron microscopy (SEM).

Cells with various combinations of ridges, blebs, filopodia, and lamellipodia were observed adhering to the posterior surface of the iris by 6 days after lentectomy. These cells, which exhibited the surface characteristics of macrophages, became more numerous in specimens fixed after longer intervals. Invasion of the iris epithelium was observed in a cryofractured specimen. After observations with SEM, selected specimens were embedded in plastic and sectioned for study with transmission electron microscopy (TEM). The cells on the iris surface had the cytological characteristics of macrophages, and other macrophages were located within the iris epithelium. In specimens fixed 16 or more days after lentectomy, a bulging lens vesicle was regenerating from the dorsal pupillary margin of the iris. Macrophages were absent or few on the surface of this developing lens but remained scattered over the adjoining iris.

Roles that might be played by these macrophages during the transdifferentiation of iris epithelium into lens are discussed.