bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deep splenic lymphatic vessels in the mouse: A route of splenic exit for recirculating lymphocytes
Authors: Pellas Theodore C. , Weiss Leon 
Published: February 2005

AbstractA 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

AbstractThe 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

AbstractDevelopment 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

AbstractThis 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

AbstractMorphometric 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

AbstractSodium‐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

AbstractWe 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

AbstractThe 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

AbstractTendon 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

AbstractThe 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

AbstractNumerous 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.