bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of spermatogonia in the stage‐synchronization of the seminiferous epithelium in vitamin‐A‐deficient rats
Authors: Ismail N. , Morales C. , Clermont Y. 
Published: February 2005

AbstractAfter 20‐day‐old rats are placed on a vitamin‐A‐deficient diet (VAD) for a period of 10 weeks, the seminiferous tubules are found to contain only Sertoli cells and a small number of spermatogonia and spermatocytes. Retinol administration of VAD rats reinitiates spermatogenesis, but a stage‐synchronization of the seminiferous epithelium throughout the testis of these rats is observed. In order to determine which cell type is responsible for this synchronization, the germ cell population has been analyzed in whole mounts of seminiferous tubules dissected from the testes of rats submitted to the following treatments. Twenty‐day‐old rats received a VAD diet for 10 weeks and then were divided into three groups of six rats. In group 1, all animals were sacrificed immediately; in group 2, the rats were injected once with retinol and sacrificed 3 hr later; in group 3, the rats were injected once with retinol, placed on a retinol‐containing diet for 7 days and 3 hr, and then sacrificed. Three rats from each group had one testis injected with 3H‐thymidine 3 hr (groups 1 and 2) or 7 days and 3 hr (group 3) before sacrifice. Three normal adult rats (approximately 100 days old) served as controls. Labeled and unlabeled germinal cells were mapped and scored in isolated seminiferous tubules. In group 1, type A1 and type A0 spermatogonia as well as some preleptotene spermatocytes were present; type A2 A3 A4 In, and B spermatogonia were completely eliminated from the testis. Neither type A1 mitotic figures nor 3H‐thymidine‐labeled‐type A1 nuclei were seen. Three hr after retinol injection (group 2), type A1 mitoses, but no labeled type A1 nuclei were observed. At 7 days and 3 hr after retinol administration (group 3), type A4 and In Spermatogonia as well as type A1 spermatogonia were present. A few residual pachytene spermatocytes were found, and some type A0 cells were labeled. These results indicate that VAD caused, in addition to an impairment of spermatogenesis at the preleptotene spermatocyte step, a selective momentary arrest of surviving type A1 spermatogonia at the G2 phase of their cell cycle. Following administration of vitamin A to VAD rats, these type A1 cells reinitiated spermatogenesis synchronously and, after several cycless of proliferation and renewai, reconstituted the seminiferous epithelium in a stage‐synchronized manner.
Regional differences in composition of the perforatorium and outer periacrosomal layer of the rat spermatozoon as revealed by immunocytochemistry
Authors: Oko R. , Moussakova L. , Clermont Y. 
Published: February 2005

AbstractThe rat perforatorium is the part of the perinuclear theca that underlies the acrosomic system. It appears to be composed of several polypeptides. The main objective of this study was to determine the distribution of seven of these perforatorial polypeptides in the head of the rat spermatozoon. For this purpose, polyclonal antibodies were affinity purified from these polypeptides and tested (1) for their distribution on electron‐microscope sections of late spermatids and spermatozoa by immunogold labeling and (2) for their specificity on Western blots of denatured perforatorial polypeptides by immunoblotting. Imunoblotting showed that all seven of the prominent perforatorial polypeptides had epitopes in common. Immunogold labeling of spermatozoa showed that antibodies against the 13, 13.4, and 16 kDa polypeptides were restricted in their localization to the thicker apical portion of the perforatorium and to the inner zone of the ventral spur. However, antibodies against the 34, 43, 57, and 63 kDa polypeptides reacted with the entire perforatorium but, in addition, reacted with the inner part of the ventral spur and with a portion of the “outer periacrosomal layer” lying between the plasma membrane and the outer acrosomal membrane. These results suggest (1) that there are regional differences in protein composition of the perforatorium, of the outer periacrosomal layer, and of the postacrosomal dense lamina; and (2) that perforatorial polypeptides may not necessarily be restricted to the subacrosomal region, but may also compose portions of the outer periacrosomal layer and postacrosomal dense lamina. Based on both immunoblotting and immunocytochemical results, using an antiactin monoclonal antibody that recognizes all known isoforms of actin, actin was not detected in the perforatorium of step 19 spermatids or spermatozoa. Actin, however, together with the seven perforatorial polypeptides tested, was present in the subacrosomal space of elongating spermatids before the process of condensation of the perforatorium takes place.
Abnormal manchette development in spermatids of azh/azh mutant mice
Authors: Meistrich M. L. , Trostle‐Weige P. K. , Russell L. D. 
Published: February 2005

AbstractA study of manchette development during spermiogenesis in azh/azh mutant mice was carried out by thin‐section transmission electron microscopy with the goal of determining which of the initial steps in spermatid development are aberrant. In the homozygous mutant, spermatogensis was quantitatively normal; but 100% of the sperm nuclei produced had abnormal shapes. The first defect, observed in steps 8–9, was the abnormal positionning of many manchette microtubules. These microtubules were directed to wards regions of the plasma membrane not normally associated with manchette formation, in addition to being located at the caudal rim of the acrosome in the normal region of manchette formation. At steps 10–12, sheets of machette microtubules were often in ectopic positions along the plasma membrane, rather than in association with the nuclear membrane as well. The fine structural appearance of the manchette was generally normal; the defect appeared to be in its positioning within the cell. In many step 8–10 spermatids nuclear invaginations and evaginations were observed, always associated with irregularities in the position of some of the manchette microtubules; these illustrate the capacity of manchette microtubules to deform nuclear shape. The nuclear irregularities remained throughout spermiogenesis. These observations are consistent with the hypothesis that the manchette is involved in at least some aspects of sperm nuclear shaping and that the improper positioning of manchette formation is a likely candidate for the primary abnormality resulting from a defective allele at the azh locus.
Microscopic examination of porcine conceptus‐maternal interface between days 10 and 19 of pregnancy
Authors: Keys J. L. , King G. J. 
Published: February 2005

AbstractConceptus‐maternal interactions in the pig were examined at days 10, 13, 16, and 19 of pregnancy. Contact between the chorion and uterine epthelium was not preserved on day 10, but extensive contact occurred in 3 to 5 pregnant gilts on day 13 and was related to localized differentiation of the uterine epithelium. Attachment events occurred earlier and more rapidly than previously reported, commencing in the region of the embryonic disc and progressing toward the extremities of the chorionic vesicle, with stages from apposition through attachment occuring simultaneously along a conceptus at day 13 and thereafter. Apical protuberances on maternal epithelial cells and interposing blunt chorionic processes were evident at sites of early maternal conceptus interaction, but were reduced at regions exhibiting microvillous interdigitation. Placentation in the pig represents a developmental process consisting of a continuum of sequential events which occur over a broad time frame rather than at specific discrete times.
Ultrastructural study of the cellular types in the pineal organ of gambusia affinis (teleost)
Authors: Gonzalez Rosa M. , Tolivia Delio , Rodriguez‐Colunga Maria J. , Menendez‐Pelaez Armando 
Published: February 2005

AbstractThe pineal organ of Gambusia affinis was studied via light and electron microscopy. The cell types studied included photoreceptor cells, supporting cells, and a third cell type. The photoreceptor cells, which appear to form clusters, are divided into four regions: outer segment, inner segment, cell soma, and synaptic pedicle. Synaptic ribbons are commonly observed in the synaptic pedicle. The supporting cells separate the photoreceptor cells from the thick basal lamina that surrounds the entire pineal organ. The supporting cells show highly organized membrane formations, some lipid‐like inclusions, and a diplosome. One of the centrioles gives rise to an invaginated cilium. The third cell type is observed infrequently and appears to be located mainly in the vicinity of the outer segments. The morphological characteristics of this cell type are similar to those of phagocytic cells. The ultrastructural features of the pineal organ of G. affinis are compared with those of other teleosts.
Nerves and nerve plexuses of the human vertebral column
Authors: Groen Gerbrand J. , Baljet Bob , Drukker Jan 
Published: February 2005

AbstractThe origin, distribution, and termination pattern of nerves supplying the vertebral column and its associated structures have been studied in the human fetus by means of an acetylcholinesterase whole‐mount method. The vertebral column is surrounded by ventral and dorsal nerve plexuses which are interconnected. The ventral nerve plexus consists of the nerve plexus associated with the anterior longitudinal ligament. This longitudinally oriented nerve plexus has a bilateral supply from many small branches of the sympathetic trunk, rami communicantes, and perivascular nerve plexuses of segmental arteries. In the thoracic region, the ventral nerve plexus also is connected to the nerve plexuses of costovertebral joints. The dorsal nerve plexus is made up of the nerve plexus associated with the posterior longitudinal ligament. This nerve plexus is more irregular and receives contributions only from the sinu‐vertebral nerves. The sinu‐vertebral nerves originate from the rami communicantes and, in the cervical region, also from the nerve plexus of the vertebral artery. Thick and thin sinu‐vertebral nerves are found. Most frequently three types of thick sinu‐vertebral nerves are observed, i.e., ascending, descending, or dichotomizing ones. Finally, the distribution of the branches of the ventral and dorsal nerve plexuses and of the sinu‐vertebral nerves is described.
Development of the embryonic chick wing bud from stage 24 to stage 32
Authors: Searls Robert L. 
Published: February 2005

AbstractIf a graft is placed in an early chick wing bud, the location of the graft after several days of further development cannot be predicted solely from the rate of proximal‐distal outgrowth. The movement of the graft depends on the rate of outgrowth of the wing but also on morphogenetic tissue movements intrinsic to the wing and on accommodation to the growth and morphogenetic movements of the body of the embryo. Numerous experiments have been reported in which tissue grafted into ectopic sites in the wing causes abnormal wing development. These experiments have been discussed in terms of pattern formation of positional information. However, until the movement of wing tissue during normal development is understood, it cannot be known in what way the development of grafts placed in ectopic sites is abnormal. Previous experiments have demonstrated that carbon particles placed in the wing move in the same manner as grafts of wing mesenchyme, but the carbon particles do not affect normal wing development. Carbon particles were placed in the wing, dorsal to the base of the wing, and cranial and caudal to the wing, to plot the expected movement of a graft and to discover how this movement can be predicted from the tissue movements at the base of the wing. It is concluded that three tissue movements are responsible for the movement of a graft. These are outgrowth at a rate determined by the rate of cell division, formation of the shoulder through caudal movement of the tissues cranial to the wing, and ventral movement of prospective flank ventral to somite 19. These three tissue movements and their influence on normal wing development are discussed.
Golden hamster myoid cells during active and inactive states of spermatogenesis: Correlation of testosterone levels with structure
Authors: Kurohmaru Masamichi , Hikim Amiya P. Sinha , Mayerhofer Artur , Bartke Andrzej , Russell Lonnie D. 
Published: February 2005

AbstractMyoid cells were examined quantitatively in adult golden hamsters with active spermatogenesis and compared with hamsters in which the testes were regressed due to a modification in the light‐dark cycle. A detailed morphometric study was undertaken utilizing animals previously examined. The cell‐surface area and volumes of most organelles were not significantly different in animals which were gonadally active as compared with regressed animals. A slight, but significant, increase in nuclear volume (31%) and a slight, but significant, decrease (28%) in cell volume were recorded for regressed animals. The total volume of pinocytotic vesicles was increased dramatically (approximately threefold) in active animals in comparison with inactive animals (P<0.01), indicating that an increase in non‐specific transport across the myoid cell is associated with spermatogenic activity. Intravascularly injected horseradish peroxidase was capable of entering pinocytotic vesicles in both active and inactive animals. Plasma luteinizing hormone (LH) as well as plasma and testicular testosterone levels were weakly (r=0.64, 0.68, and 0.65, respectively), but significantly (P<0.05), correlated with cell size. Plasma and testicular testosterone were correlated with the total volume of pinocytotic vesicles (r=0.74 and 0.68, respectively). The data indicate that although the rat myoid cell possesses receptors for testosterone, there are few structural manifestations of the hamster myoid cell that correlate well with testosterone levels. Thus, the hamster myoid cell differs from two other hormone‐responsive somatic cells in the testis, the Sertoli cell and the Leydig cell, that show dramatic structural alterations with changes in gonadal activity and striking correlations of structural features with functional measures. These findings were unexpected in view of the in vitro findings that point to a major role for the myoid cell in controlling seminiferous tubule function.
Macrophage invasion and phagocytic activity during lens regeneration from the iris epithelium in newts
Authors: Reyer Randall W. 
Published: February 2005

AbstractFollowing removal of the lens through the cornea, early stages of lens regeneration from the dorsal riris of the adult newt, Notophthalmus viridescens, were studied using light and electron microscopic observations on sectioned, plastic‐embedded irises. Specimens were fixed in Karnovsky's fixative every 2 days from 0 to 12 and 15 days after lentectomy. Infiltration of the iris epithelium by macrophages and their phagocytosis of melanosomes and small fragments of iris epithelial cells were observed. These macrophages were characterized by coarse nuclear chromatin, numerous mitochondria, free ribosomes, granular endoplasmic reticulum, Golgi complexes, vesicles, lysosomes, and phagosomes containing ingested melanosomes. Lamellipodia of varying length projected from their surface. Most of the cells lying on or close to the posterior surface of the iris could be identified as macrophages by these criteria. During this period, there was enlargement of the intercellular spaces within the iris epithelium. The iris epithelial cells near the margin of the pupil elongated, lost their melanin pgigment and some associated cytoplasm, and acquired abundant free polyribosomes to form a lens vesicle of depigmented cells.
In vivo differentiation of brown adipocytes in adult mice: An electron microscopic study
Authors: Géloën A. , Collet A. J. , Guay G. , Bukowiecki L. J. 
Published: February 2005

AbstractThe differentiation of brown adipocyte precursor cells was studied in interscapular brown adipose tissue of adult mice by electron microscopy. Different stages of cell differentiation were characterized in situ. Previous autoradiographic studies suggested that interstitial cells represent the precursor cells of fully differentiated brown adipocytes. The present observations provide morphological evidence for a progressive differentiation of interstitial stem cells into mature brown adipocytes. Four typical stages of development were identified: (1) interstitial cells, (2) protoadipocytes, (3) preadipocytes, and (4) mature brown adipocytes. Interstitial stem cells were small spindle shaped cells, situated between brown adipocytes and characterized by a high nuclear‐cytoplasmic ratio, the scarcity of organelles, and the absence of lipid inclusions. Protoadipocytes resembled interstitial cells except that they contained a few tiny lipid droplets in their cytoplasm. Preadipocytes had a larger cytoplasm enclosing many mitochondria and lipid droplets; the smooth endoplasmic reticulum was well developed surrounding the lipid droplets, and was closely associated with the mitochondria. Preadipocytes had the typical structure of growing cells, developing long cytoplasmic processes between and around blood capillaries. Mature brown adipocytes represented the final stage of differentiation. Almost all their cellular volume was occupied by lipid droplets and numerous mitochondria with very dense cristae. Brown adipocytes were also characterized by a tight association with blood capillaries, as expected from metabolically active cells requiring oxygen and substrates. These observations provide direct ultrastructural evidence for a progressive differentiation of interstitial cells into brown adipocytes with a continuum of intermediate cellular types.
Membrane modifications in chick osteoclasts revealed by freeze‐fracture replicas
Authors: Akisaka Toshitaka , Yoshida Hisaho , Kogaya Yasutoku , Kim Songchol , Yamamoto Masao , Kataoka Katsuko 
Published: February 2005

AbstractRemarkable differences among various membranes of bone cells became evident by examination of freeze‐fracture replicas. In osteoclasts, three types of intramembranous particles (IMPs) were identified based on their size and shape: two sizes of isolated globular particles (8 and 12 nm in diameter) and rod‐shaped, linear aggregates (8 × 30 nm in dimension). Furthermore, the density and distribution pattern of these IMPs enabled us to distinguish three different domains of membranes of osteoclasts including reffled border, clear zone, and basolateral regions, as were also observed in thin sections. The highest density of IMPs was 3,500‐4,000/μm2 in the ruffled border membrane, and these IMPs included linear aggregates among the usual globular particles. Linear aggregated particles were also observed in the membrane of cytoplasmic vesicles in the vicinity of the ruffled border region, but not in this membrane in other bone cells. In attached osteoclasts, the distribution pattersn and densities of IMPs in each ruffled‐finger and ‐plate were extremely variable, from closely to the loosely packed membrane particles. Focal aggregates of membrane particles were also frequently encountered. An important outcome of the present study was the finding that the presence of linear aggregated particles proved to be an additional criterion for distinguishing membrane domains in freeze‐replicas of osteoclasts. The surface of the clear zone membrane was not smooth in profile, but revealed a number of eminences that were almost free of particles. Basolateral membranes exhibited a particle density of 2,400/μm2. Globular particles were homogeneously scattered in random fashion on their exposed fracture faces. In some cases, aggregates of IMPs on the basolateral membranes were encountered. In comparison with the ruffled fingers, microprojections from the basolateral surface showed a lesser density of IMPs and were devoid of rod‐shaped or linear aggregated particles. Differences between osteoblasts and osteocytes were apparent in the density and the size of IMPs. The membranes of osteoblasts and osteocytes contained the same types of globular particles as seen in osteoclasts. Various sizes of gap junctions were located only on basolateral membranes of the osteoblasts. In contrast, no cellular junctions were observed between osteoclasts and any other type of cells.
Spatial differences of endogenous lectin expression within the cellular organization of the human heart: A glycohistochemical, immunohistochemical, and glycobiochemical study
Authors: Bardosi A. , Bardosi L. , Hendrys M. , Wosgien B. , Gabius H‐J. 
Published: February 2005

AbstractProtein‐carbohydrate recognition may be involved in an array of molecular interactions on the cellular and subcellular levels. To gain insight into the role of proteins in this type of interaction, surgically removed specimens of human endomyocardial tissue were processed for histochemical and biochemical analysis. The inherent capacity of these sections to bind individual sugar moieties, which are constituents of the carbohydrate part of cellular glycoconjugates, was assessed using a panel of biotinylated neoglycoproteins according to a standardized procedure. Together with appropriate controls, it primarily allowed localization of endogenous lectins. Differences in lectin expression were observed between layers of endocardial tissue, myocardial cell constituents, connective‐tissue elements, and vascular structures. The endocardium proved to be positive with β‐galactoside‐bearing probes; with neoglycoproteins carrying β‐xylosides, α‐fucosides, and galactose‐6‐phosphate moieties; and with probes containing a carboxyl group within the carbohydrate structure, namely sialic acid and glucuronic acid. In contrast, only fucose‐and maltose‐specific receptors were apparent in the elastic layers of the endocardium. Aside from ascertaining the specificity of the protein‐carbohydrate interaction by controls, i.e., lack of binding of the probe in the presence of the unlabelled neoglycoprotein and lack of binding of the labelled sugar‐free carrier protein, respective sugar receptors were isolated from heart extracts by using histochemically effective carbohydrates as immobilized affinity ligand. Moreover, affinity chromatography using immobilized lactose as affinity ligand as well as the use of polyclonal antibodies against the predominant β‐galactoside‐specific lectin of heart demonstrated that the lactose‐specific neoglycoprotein binding was due to this lectin. Remarkably, the labelled endogenous lectin, preferred to plant lecins for detecting ligands of the endogenous lectin, localized ligands in tissue parts where the lectin itself was detected glycohistochemically as well as immunohistologically. This demonstration of receptor‐ligand presence in the same system is a further step toward functional assignment of the recorded protein‐carbohydrate interaction. Overall, the observed patterns of lectin expression may serve as a guideline to elucidate the precise physiological relevance of lectins and to analyze pathological conditions comparatively.