bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of immature leydig cells in the human prepubertal testis
Authors: Prince Frederick P. 
Published: February 2005

AbstractThe cellularity of the human prepubertal testicular interstitium has not been well studied at the ultrastructural level. In this study, testicular biopsies were obtained from 35 boys aged three to nine years and examined by electron microscopy to clarify and quantitate the cell types present during the prepubertal period.The prepubertal testicular interstitium is found to consist of immature Leydig cells (9%), primitive fibroblastic cells (63%) (intertubular in location), and attenuated peritubular fibroblasts (28%). The primitive fibroblastic cells and peritubular fibroblasts appear closely related, being distinguished mainly by shape and location. The immature Leydig cell type contrasts with the fibroblastic cell types by exhibiting an irregular nucleus with relatively little heterochromatin. The most impressive cytoplasmic feature is the moderate to extensive development of smooth endoplasmic reticulum in the form of anastamosing tubules. In contrast, the rough endoplasmic reticulum is not well developed. Other cytoplasmic characteristics are the highly developed Golgi elements and occasional lipid droplets and lysosomes. Glycogen is also often present and is generally found in those cells that do not contain a welldeveloped smooth endoplasmic reticulum. The ultrastructure of the immature Leydig cell is compared with that of the mature fetal and adult Leydig cells. Although generally found in small clusters between tubules, these cells are often attenuated and closely associated with the seminiferous tubules. Occasional intermediate cell morphologies suggest a relationship between the primitive fibroblasts and immature Leydig cells.The presence of small cells exhibiting a steroid‐producing morphology, classified as immature Leydig cells, in the prepubertal testicular interstitium is an interesting finding and is in accordance with earlier studies on nonhuman mammals. It is unknown whether these cells are remnants of the fetal Leydig cell population or have differentiated neonatally from the primitive fibroblastic cells. It is suggested that the immature Leydig cells are the progenitors of the adult Leydig cell population.
Disposition of the manchette in the normal equine spermatid
Authors: Goodrowe Karen L. , Heath Everett 
Published: February 2005

AbstractBielanski and Kaczmarski (1979) reported the presence of microtubules in the neck region of mature stallion spermatozoa. It was hypothesized that these microtubules are derived from the manchette (a microtubular organelle present during spermiogenesis). In order to test this hypothesis, testes from 15 mature stallions were collected, perfused with 2% phosphatebuffered glutaraldehyde, and prepared for transmission electron microscopy. Spermatozoa from the caudae epididymides of each stallion were prepared in a similar manner. Spermiogenesis was observed in general, and the presence of a microtubular manchette was established in this species, juxtapositioned posterior to the nuclear ring and extending distally into the cytoplasmic collar which surrounds the prospective midpiece. Interlocking arms between the microtubules of the manchette were observed in transverse sections at all levels within the cytoplasmic collar before, during, and after caudal migration of the nuclear ring. Consequent to caudal migration of the nuclear ring and the annulus, as well as adluminal movement of the spermatid, the cytoplasmic collar was transformed into the residual cytoplasm. Within the residual cytoplasm, the manchette remained as a microtubular organelle which undergoes degeneration. The mature spermatozoa from the caudae epididymides of these stallions lacked the microtubules reported by Bielanski and Kaczmarski. The occurrence of such microtubules in the neck region of stallion spermatozoa is probably an abnormality.
Endocytosis in epithelial cells lining the rete testis of the rat
Authors: Morales C. , Hermo L. , Clermont Y. 
Published: February 2005

AbstractThe endocytic activity of the low cuboidal cells lining the rete testis was analyzed by electron microscopy following injection of various tracers into the lumen of these anastomotic channels. At 1 and 5 minutes after injection, cationic ferritin (CF) and concanavalin A‐ferritin (Con A) were seen bound to the apical plasma membrane and to the membrane of subjacent vesicles or invaginations connected to this apical membrane. At 30 and 60 minutes, these tracers were found in intracytoplasmic vesicles and in vesicles connected to the lateral or basal plasma membrane as well as in the lateral intercellular space and in the lamina lucida of basal lamina. At 30 minutes, CF and Con A also appeared in the matrix of pale multivesicular bodies while at 1 hour dense multivesicular bodies were labeled. At 2 hours and later time intervals, the tracers accumulated in dense granules identified as lysosomes. Native ferritin (NF), concanavalin A‐ferritin in presence of α‐methyl‐D‐mannoside, and horseradish peroxidase or albumin bound to colloidal gold were all to be incorporated by the lysosomal system of these epithelial cells, as just described for CF and Con A, but these various tracers were not bound to the apical plasma membrane or to the membrane of cytoplasmic vesicles, nor were they found in the intercellular spaces or the lamina lucida at the base of the cells. Thus, the epithelial cells of the rete testis do not appear to be only involved in the uptake of substances from the lumen and their disposal by the lysosomal system, but also appear to contribute to the transport of certain macromolecules from the lumen to the laterobasal surfaces of the cells. These cells may thus play a role in determining the composition of the rete testis fluid.
Differentiation of cultured palatal shelves from alligator, chick, and mouse embryos
Authors: Ferguson Mark W. J. , Honig Lawrence S. , Slavkin Harold C. 
Published: February 2005

AbstractPalatal shelves from embryonic alligators, chicks, and mice were explanted at various stages of development and organ cultured in either chemically defined, serumless media or the same media supplemented with 10% fetal calf serum. Shelves from each vertebrate were either cultured singly or in contact, and heterologous combinations of palatal shelves from different animals were made: chick/mouse, chick/alligator, and mouse/alligator. Epithelial differentiation (particularly that of the medial shelf edge) was assayed by vital staining, histology, and scanning electron microscopy. In vitro medial edge epithelial differentiation, and consequently the mechanisms of palatal closure, were identical to those normally seen in vivo for each species, i.e., cobble‐stoned migrating epithelia in the alligator, cell death and fusion in the mouse, and keratinisation and cleft palate in the chick. Differentiation was optimal in the chemically defined, serumless media and was independent of shelf contact in all three species. No heterologous combinations of palatal shelves closed with each other: Evidently, the modes of palatal closure in mice and alligators are sufficiently different to prevent them forming a chimeric palate, whilst neither is capable of inducing closure in a cocultured chick palatal shelf. These unified defined culture conditions make possible a large number of epithelial‐mesenchymal recombination studies as well as specific inhibitor, teratogenic, and hormonal investigations.
Some histochemical properties of the fiber types in the pectoralis muscle of an emu (Dromaius novaehollandiae)
Authors: Rosser Benjamin W. C. , George John C. 
Published: February 2005

AbstractThe muscle fibers of the cranial slip of M. pectoralis pars thoracica of an emu (Dromaius novaehollandiae) were studied histochemically for intracellular lipid, succinic dehydrogenase, myofibrillar adenosine triphosphatase, and acetylcholinesterase. It was concluded that the muscle consisted of approximately 28% slow‐tonic and 72% fast‐twitch glycolytic fibers. The tonic fibers were considered to be characteristic of a postural muscle, and the fasttwitch glycolytic fibers to reflect the inability of the muscle to engage in sustained activity. The general absence of slow‐tonic fibers from the pectoralis of other avian species so far studied may be attributed to inadequate sampling of the deeper regions of the muscle.
Circadian influence on the metaphase arrest technique in mouse cornea (light microscopy study) and rectum (flow cytometry study)
Authors: Burns E. Robert 
Published: February 2005

AbstractVincristine (VC) was used to arrest metaphases in the epithelium of the cornea and rectum. The cornea was studied by light microscopy (mitotic index). The rectum was analyzed by flow cytometry (%G2+M). The results of a dose range finding study showed that 3.0 mg/kg body weight VC did not increase the number of metaphases in the cornea or the %G2+M for the rectum over that recorded for a dose of 1.0 mg/kg VC. Therefore 1.0 mg/kg VC was selected as the dose to use. Mice were kept on a 12:12 light‐dark cycle with light from 0600 to 1800. Mice were treated with 1.0 mg/kg VC at either 0200 or 1400. 0200 is a time when the native mitotic index is increasing toward a peak level, which is attained at 0800–1000 under these conditions. 1400 is a time when the mitotic index is decreasing to trough level, which is attained at 2000 to 2200. In one experiment, subgroups of mice were killed at +3 (0500 or 1700) and +6 (0800 or 2000) hours after VC. In a replicate experiment subgroups were killed at +2 (0400 or 1600), +4 (0600 or 1800), and + 6 (0800 or 2000) hours after VC. The data from the cornea (mitotic indices) and the rectum (%G2+M) were graphed against time. For both organs the slope of the metaphase accumulation line was different when VC at 0200 data were compared to VC at 1400 data. The conclusion reached was that by changing the biological time of the experiment one can significantly change the slope of the line obtained with the stathmokinetic technique.
Iron deposition in the integument of lampreys
Authors: Youson J. H. , Sargent P. A. 
Published: February 2005

AbstractThe integument of larval, parasitic adult, and upstream‐migrant lampreys (Petromyzon marinus) was examined for iron deposition using light microscopic histochemistry and routine and histochemical procedures in the electron microscope. Ferritin particles, representing ferric iron, are present throughout most of the cytoplasmic matrix and within dense granules and vacuoles of epidermal mucous cells, but are not located in skein or granular cells. These particles are abundant in mucous cells of the dorsal surface but not the ventral surface and are more concentrated in adult lampreys compared to larva. Histochemistry revealed only sparse amounts of ferrous iron. Iron is not present in the dermis but is found in adipocytes of a subcutaneous layer. The deposition of integumentary iron is discussed with reference to body pigmentation and excretion of this metal.
Filamentous actin bundles in the kidney
Authors: Andrews Peter M. , Bates Sally B. 
Published: February 2005

AbstractThe distribution of filamentous actin bundles in the rat kidney was studied using a fluorescent phallotoxin label and transmission electron microscopy. The microvillous brush border lining proximal tubules, smooth muscle in renal vessels, and renal corpuscles were the structures most intensely labeled with rhodamine phalloidin. Closer evaluation of renal copuscles revealed intense labeling of filamentous actin within podocyte foot processes eveloping the glomerular capillary loops. Rhodamine phalloidin also labeled basal bands of filamentous actin in the parietal epithelium and basal bands of actin in proximal and distal tubules. Finally, a band of filamentous actin was evident along the innermost aspect of the kidney capsule, within cells which often joined to form sinus‐like compartments.
Cytoskeleton ultrastructure of podocytes and glomerular endothelial cells in man and in the rat
Authors: Vasmant Daniel , Maurice Michele , Feldmann Gerrard 
Published: February 2005

AbstractThe ultrastructural organization of the cytoskeleton of normal podocytes and glomerular endothelial cells was studied in man (adults and children) and in adult Sprague‐Dawley rats. In podocytes of both speicies, cytoplasmic microtubules (MT) were observed in the cell body close to the Golgi apparatus and along the main axis of the major processes where they formed bundles. A network of intermediate filaments (IF) was observed in the cell body and in the major processes where they sometimes formed bundles parallel to MT, especially in man. Numerous clustered microfilaments (MF) were noticed in the foot processes close to the plasma membrane. In glomerular endothelial cells from both species, networks of MT and IF were observed in the cell body, whereas MF surrounded the endothelial fenestrations. The high degree of organization of the cytoskeleton suggests that it may play an important role in several functions of both cell types.
Carbohydrate cytochemistry of rhesus monkey tracheal epithelium
Authors: St. George Judith A. , Nishio Susan J. , Plopper Charles G. 
Published: February 2005

AbstractThree types of nonciliated secretory epithelial cells contribute material to the mucous lining of pulmonary airways: mucous cells, serous cells, and Clara cells. Extensive interspecies variation exists, especially between humans and laboratory mammals, with regard to occurrence, distribution, and granule content of these secretory cells. This study was designed to characterize one aspect of these differences in one species of nonhuman primate, the rhesus monkey. The complex carbohydrates of secretory granules present in the tracheal epithelium were characterized cytochemically. The tracheas of seven monkeys were fixed by airway infusion, processed, and embedded for both light and transmission electron microscopy. Histochemical stains including Alcian blue‐periodic acid Schiff, dialyzed iron, and high iron diamine‐Alcian blue were applied to serial methacrylate sections. The mucous cells were the predominant secretory cell type of the trachea and contained periodate‐reactive sulfated glycoconjugates. The mucous secretory granules, as resolved with the electron microscope, consisted of a mesh or matrix surrounding a biphasic core. The matrix was stained by all cytochemical reactions used, which included periodic acid‐thiocarbohydrazide‐silver proteinate, dialyzed iron, low iron diamine, and high iron diamine. The biphasic core also reacted with the four stains, but most intensely with high iron diamine. We conclude from this study that (1) the mucous secretory granule contains carbohydrate throughout all phases of the granule, (2) the mucous granule contains periodate‐reactive sulfated glycoconjugates, with sulfate esters concentrated in the core of the granule, and (3) the mucous granules of rhesus trachea morphologically and cytochemically resemble those described in human airways.
Ganglionic character of mesencephalic trigeminal neurons in the turtle Mauremys caspica
Authors: Fernández Elvira F. , Doel Rosa Paz 
Published: February 2005

AbstractA study of the morphology of the mesencephalic trigeminal neurons and their arrangement in the optic tectum has been made in the turtle Mauremys caspica employing the Cajal reduced silver method. The ganglionic features of its neurons suggest that the mesencephalic trigeminal nucleus (MTN) is a diffuse sensory ganglion located in the central nervous system. The different distribution of two cell populations, probably as a result of a distinct embryonic origin of their elements, and the atypical pattern of the ependyma lying underneath the MTN are discussed.
Intercellular junctions in upper airway submucosal glands of the rat: A tracer and freeze fracture study
Authors: Schneeberger E. E. , McCormack J. M. 
Published: February 2005

AbstractThe structure of intercellular tight junctions of rat airway submucosal glands was examined by freeze fracture techniques and their permeability assessed by the use of colloidal lanthanum. The submucosal glands were organized into three distinct regions: (a) serous tubules and (b) mucous tubules lined, respectively, by serous and mucous cells, and (c) ducts lined by cuboidal epithelial cells, containing few secretory granules, and some ciliated cells. The mean number of parallel fibrils constituting the tight junctions between serous cells was 3.6 ± 0.4, which was significantly smaller than those between any of the other cell types. Colloidal lanthanum permeated the tight junctions between serous cells up to the level of the acinar lumen. There was a progressive increase in the mean number of parallel fibrils of tight junctions between mucous (5.1 ± 0.6), ductal (5.4 ± 0.5), and ciliated cells (8.5 ± 0.7); none of these junctions was permeated by colloidal lanthanum. These results imply that tight junctions between serous cells are more permeable to small water‐soluble solutes than those present in the more proximal portions of the gland. Gap junctions were observed between serous cells and between mucous cells, suggesting that these secretory cells may be electotronically and metabolically coupled.
A combined scanning electron microscopy and immunofluorescence study demonstrating that the odontoblast process extends to the dentinoenamel junction in human teeth
Authors: Sigal M. J. , Pitaru S. , Aubin J. E. , Ten Cate A. R. 
Published: February 2005

AbstractThe extent of the odontoblast cell process has been the subject of controversy for many years. Using SEM we have examined the extent and morphology of the process on dentine surfaces of human teeth which were partially demineralized and collagenase digested. Third molars were extracted and split; the dentine surface was demineralized, digested by bacterial collagenase, fixed with glutaraldehyde, postfixed in osmium tetroxide, and prepared for SEM investigation. The SEM study revealed the presence of many processlike structures which extended from the odontoblast cell bodies up to the dentinoenamel junction (DEJ). These processes demonstrated lateral and terminal branching and some of them terminated in distended spheres. We have also applied an immunofluorescence technique at the light microscope level to these exposed dentinal surfaces to localize the intracellular microtubules. For this, a second series of third molars was processed in the same manner as for the SEM up to the fixation stage. Teeth were then fixed in periodate‐lysine‐paraformaldehyde, postfixed in −20°C acetone, and then incubated with affinity‐purified rabbit antitubulin antibodies, followed by fluorescein‐conjugated goat antirabbit IgGs. Intratubular immunofluorescence labelling for tubulin was evident from the odontoblast cell bodies up to the DEJ. The presence of the tubulin‐containing structures extending to the DEJ supports the hypothesis that the structures observed with the SEM are odontoblast processes and that the odontoblast processes do extend to the DEJ.
Ultrastructure of the parotid gland in the little brown bat
Authors: Tandler Bernard , Cohan Richard P. 
Published: February 2005

AbstractThe ultrastructure of the parotid gland was examined in the little brown bat. The seromucous acinar cells contained abundant granules of variable morphology. These granules were characterized by a submembranous dense layer consisting of fine parallel slats. In some bats, the matrix of the granules was structureless, whereas in others it consisted of closely packed but randomly arranged bundles of tubules. The intercalated ducts had a highly developed rough endoplasmic reticulum, often containing large numbers of intracisternal granules. In contrast, only a few secretory granules were present in the supranuclear cytoplasm. The striated ducts, which exhibited the characteristic basal striations consisting of vertically oriented mitochondria and highly folded plasmalemmas, contained numerous small dense granules in a subluminal band. These granules had a paracrystalline substructure with a periodicity of 8 nm. Excretory ducts strongly resembled striated ducts. They showed the same kind of basal striations and about half their constituent cells contained small paracrystalline granules.
The ultrastructure of oral (buccopharyngeal) membrane formation and rupture in the anuran embryo
Authors: Watanabe Kyozo , Sasaki Fumie , Takahama Hideki 
Published: February 2005

AbstractThe ultrastructure of the oral (buccopharyngeal) membrane was examined by transmission and electron microscopy in the anuran, Rana japonica, embryo. The stomodeum is recognizable on the ventral surface anterior to the neural folds as the neural folds are beginning to close (neural tube stage). The stomodeum is gradually enlarged and deepened as development proceeds. At the neural tube stage, the oral membrane is 5–7 cell layers thick and the stomodeal ectodermal cells are cuboidal and the foregut endodermal cells are cuboidal or columnar. Desmosomes and basal lamina could not be found between the ectodermal and endodermal epithelia. The oral membrane gradually thins between the neural tube and hatching stages. At the hatching stage, the oral membrane becomes two or three cell layers thick and each cell is flattened. Many perforations of the oral membrane occur after hatching and the oral membrane appears “net‐like.” Necrotic cells occur in the oral membrane and these cells contain many autophagic vacuoles. ACPase‐positive lysosomes, Golgi regions, and autophagic vacuoles were present in the oral membrane. At the asymmetrical trunk stage, a large part of the oral membrane disappears and only remnants are left.
An implant labeling technique employing sable hair probes as carriers for 3H‐thymidine: Applications to the study of facial morphogenesis
Authors: Patterson Scott B. , Johnston M. C. , Minkoff R. 
Published: February 2005

AbstractAn implant labeling technique is described that utilizes sable hair probes as carriers for a tritiated thymidine marker. The protocol that was developed produced localized labeling of specific embryonic cell populations. This procedure was applied to the analysis of facial process development in chick embryos.Evaluation of the technique demonstrated that the probe preparation procedure was consistently successful in producing labeled probes. Using labeled probes, the procedure was reliable in producing acceptable levels of labeling in chick embryonic tissues and labeling of localized cell populations was possible using the implant labeling technique. Surrounding the center of labeling, a gradient in intensity of labeling was often observed. This pattern presumably reflects declining availability of labeled thymidine as distance from the probe increased. The technique allowed excellent survival rates to be achieved provided that aseptic procedures were followed. Additionally, careful analysis of older embryos failed to reveal any malformations induced by the implant labeling procedure.The localized labeling patterns that were demonstrated during this investigation suggest that the implant labeling technique would provide a useful tool for following cell migration during facial process formation.