bluuebunny/crossref_metadata_2025_split huggingface dataset:
Erythropoiesis in the yolk sac of the bat Tadarida brasiliensis cynocephala
Authors: Stephens Robert J. , Cabral‐Anderson Linda J. 
Published: February 2005

AbstractThe process of erythropoiesis and vasculogenesis in the yolk sac of the bat (Tadarida brasiliensis cynocephala) has been studied through the use of both light and electron microscopy. Stem cells arise from the leading edge of the migrating splanchnic mesoderm and transform into primitive erythroblasts. Differentiation involves either contact or association with the endodermal cells, since all erythropoietic activity occurs on the endodermal side of the expanding vascular bed, and many of the cells are in close apposition to the lateral or basal plasma membranes of the endodermal cells. Endodermal cells also phagocytize developing primitive erythroblasts during the later stage of the process when erythropoiesis is subsiding in the yolk sac.Cells destined to become the endothelium of the expanding vascular bed also arise from the leading edge of the migrating splanchnic mesoderm. Their process of differentiation involves the development of cytoplasmic extensions that may surround a group of differentiating erythroblasts, enclosing them in the newly formed lumen of the blood vessel. The cytoplasmic extensions make contact and develop junctional complexes with similar processes from other cells to complete the lumen of the lengthening vascular bed.Cells of the granulocyte series or megakaryocytes are not observed in the yolk sac of the bat as has been described in certain other species.
Structural characterization and rapid manual isolation of a reptilian testicular tunic rich in Leydig cells
Authors: Neaves William B. 
Published: February 2005

AbstractDuring the annual breeding season, the testes of the lizard Cnemidophorus gularis are yellow‐orange, ovoid organs measuring almost 1 cm in greatest diameter. The pigment is confined to the testicular tunic, which contains a zone of Leydig cells and vascular channels more than 50 m̈ thick. Leydig cells constitute approximately 60% of the zone, with remaining space occupied by capillaries, sinusoids, and lymphatic vessels. Lymphatics are concentrated at the interface between tunic and seminiferous tubules. Interstitial space is poorly developed among the tubules, accounting for less than 3% of tissue volume. Capillaries, lymphatics, and a few widely scattered Leydig cells occur in the sparse interstitial space. Leydig cells in the tunic and elsewhere in the testis show ultrastructural features commonly found in mammalian Leydig cells. Separation of the tunic from the seminiferous tubules is achieved in a few seconds by manual decapsulation of the testis and yields an enriched preparation of Leydig cells that is essentially uncontaminated by tubular elements.
Electron microscopic study of the developing lateral‐line organ in the embryo of the newt, Triturus pyrrhogaster
Authors: Sato Atsuko 
Published: February 2005

AbstractThe morphological sequence of events occurring in the development of the lateral‐line organ was investigated in the embryo of the newt, Triturus pyrrhogaster, by means of electron microscopy. Six stages of development have been defined for convenience of description. The primordium of the lateral‐line organ migrating from the pre‐ and post‐auditory placodes is segmented into a small cell mass accompanied by a few Schwann cells enveloping nerve fibers. In the clump of cells of the lateral‐line primordium, three kinds of cells are already distinguished by different degrees of darkness, i.e., dark, light and slightly dark cells (stage I). Both clump and Schwann cells enter the epidermis together (stage II). The two groups of cells are separated by the inner layer of the epidermis (stage III). The organ‐forming cells elongate and the inner layer of the epidermis separates the Schwann cells from the clump (stage IV). The apexes of the organ‐forming cells are exposed out of the epidermis (stage V). The lateral‐line organ is almost matured. The dark cells correspond to type II of the supporting cells, the light cells correspond to type I of the supporting cells and the slightly dark cells correspond to the receptor cells because of the existence of cilia and a cuticular plate. The afferent nerve endings are found on the basal surface of the receptor cell (stage VI).
The fine structure of the interstitial tissue of the testis of the nine‐banded armadillo
Authors: Weaker Frank J. 
Published: February 2005

AbstractThe interstitial tissue of the testis of the nine‐banded armadillo is composed of blood vessels, clusters of Leydig cells, the usual connective tissue elements, and a network of lymphatic sinusoids. The endothelial walls of the sinusoids are separated from the peritubular contractile cell layer surrounding the seminiferous tubules by a thin layer of collagen. The peritubular contractile cell is characterized by filaments and dense bodies within the cytoplasm, whereas the endothelial cells lack these structures. Within each cluster, several Leydig cells surround one or more blood vessels. Adjacent Leydig cells are joined by 2‐ to 3‐nm wide gap junctions and desmosome‐like specializations. The Leydig cell is polygonal in shape with an ovoid nucleus. The cell is characterized by an abundance of smooth endoplasmic reticulum which appears as sheets of membranes, concentric whorls around vacuoles, and a random tubular network. Only a few short cisternae of rough endoplasmic reticulum are observed. Centrioles are closely associated with the Golgi apparatus. Rod‐like mitochondria with tubular cristae are scattered throughout the cytoplasm. In addition, the cells contain vacuoles resulting from lipid extraction, filaments, microtubules, and glycogen. The surfaces of the cell exposed to the intercellular spaces exhibit numerous pinocytotic vesicles and cell processes which indicate active movement of material across the plasma membrane. In comparison to other mammalian species, the ultrastructural organization of the interstitium and the fine structure of the Leydig cell of the armadillo resemble those of the guinea pig.
The fatty ridge and fatty cushion of the human pulmonary trunk
Authors: Nadkarni Shrirang D. , Inamdar Madhavamurti H. , Ayya M. K. Chandrashekhar 
Published: February 2005

AbstractPresence of a ridge of fatty tissue running obliquely upwards and backwards over the left aspect of the pulmonary trunk was observed. It started from the left end of the infundibulo‐truncal junction and after running parallel adjacent to free anterior border of the left auricle, terminated into an expanded, oval and discoid structure, a little above the level of the tip of the left auricle. The structure was found to be of constant occurrence, position and form.A comparison between similar structure reported in relation with the aorta and the right auricle was attempted.
Efferent arterioles in the cortex of the rat kidney
Authors: Evan Andrew P. , Dail William G. 
Published: February 2005

AbstractAlthough a number of morphological studies have investigated the vascular system of the rat kidney, minimal data are available on the detailed anatomy of the efferent arterioles located throughout the cortex of the kidney. In the present study, the renal vascular system was filled with Microfil and the various efferent arteriole patterns were examined extensively. The efferent vessels of the entire cortex appear to form three major patterns which in turn divided the cortex into three separate regions: the outer, middle and inner cortex. The efferent arterioles of the outer cortex leave the glomerulus and run perpendicular to the kidney capsule. However, as the efferent arterioles ascend, they may show three variations in the way they branch: (1a) the efferent arteriole does not branch until directly beneath the capsule, (1b) the efferent vessel begins to divide into its major branches 100–200 μm below the surface of the kidney and (1c) the efferent vessel has only a short course before giving off many side branches. In the middle cortical area, the branches of the efferent arteriole run lateral to the glomerulus. However, the efferent arterioles of the inner cortex have a few branches which run lateral to the glomerulus while most of them descend into the medulla as vasa rectae. The unique morphological features of the efferent arterioles of the outer cortex are of particular interest in light of the functional data which suggests that the reabsorption of fluid by peritubular capillaries may indeed regulate the rate of net tubular sodium reabsorption.
Ultrastructural localization of peroxidase in leukocytes of rat bone marrow and blood
Authors: Bentfeld Mary E. , Nichols Barbara A. , Bainton Dorothy F. 
Published: February 2005

AbstractThe differentiation of leukocytes in the bone marrow and blood of normal adult male rats was studied by electron microscopy and peroxidase cytochemistry. Tissue samples were fixed in glutaraldehyde, or paraformaldehyde‐glutaraldehyde, and incubated in a peroxidase medium containing 3,3′‐diaminobenzidine and H2O2 at pH 7.6. Mature cells of blood were identified, and then the earlier stages of maturation in bone marrow were analyzed. In immature cells of four cell lines, neutrophils, monocytes, basophils, and eosinophils, peroxidase is synthesized and could be demonstrated in the rough endoplasmic reticulum (RER), Golgi complex, and in cytoplasmic granules. Later in maturation, reaction product for peroxidase could not be found in RER or Golgi complex, indicating that peroxidase synthesis had ceased. In two cell lines, neutrophils and monocytes, peroxidase‐negative granules were formed, and the mature cells contained two populations of cytochemically distinct granules. All granules of mature eosinophils were peroxidasepositive. In mature basophils, some granules were clearly peroxidase‐positive; others displayed variable density, making interpretation uncertain. Mast cells were never seen in blood, but were abundant in bone marrow; peroxidase was never found in their granules by either electron microscopic cytochemistry or a variety of light microscopic methods. Hence, these cells differ from basophils, not only in morphology but also in the enzyme content of their granules.
Effects of denervation and tenotomy on the gastrocnemius muscle in the frog: A histologic and histochemical study
Authors: Sarnat Harvey B. , Portnoy Jay M. , Chi David Y. K. 
Published: February 2005

AbstractThe effects of denervation on the gastrocnemius muscle of the frog were studied by histologic and histochemical methods. Thirteen Rana pipiens underwent unilateral sciatic neurotomy and were sacrificed weekly as long as 46 days. Of the three normal populations of muscle fibers, the small fibers underwent atrophy, the intermediate sized fibers remained unchanged in size, and the large fibers either did not change or underwent hypertrophy between 21 and 46 days. Necrosis of muscle fibers did not occur. Histochemical stains showed persistence of the normal pattern after denervation. The small fibers continued to have a high concentration of both oxidative and glycolytic enzyme activity (NADH‐TR, SDH, phosphorylase), and the large fibers continued to have a low concentration of these enzymes. Depletion of glycogen stores was seen with PAS. Hypertrophic muscle fibers had mostly subsarcolemmal nuclei and few internal nuclei, suggesting that they may be physiologically tonic rather than twitch fibers. Achilles tenotomy at the time of denervation prevented the hypertrophy of large fibers. Abnormal inclusions have been demonstrated in mammalian muscle following tenotomy alone, but were not seen in the frog.
Compensatory responses in the development of the brachial lateral motor column in triploid Rana pipiens
Authors: Pollack Emanuel D. , Koves Judi 
Published: February 2005

AbstractResponses of the lateral motor column (LMC) in the frog spinal cord to various experimental manipulations generally are manifested in an adjustment of the number and sizes of the motor neurons. Analysis of the brachial LMC in induced‐triploid Rana pipiens larvae as compared to diploid controls revealed a significant increase in nuclear size with a concomitant reduction in cell counts at all stages of development examined. These compensatory responses of the LMC to polyploidy in normal size frog larvae are consistent with results reported for other amphibian polyploid tissues and serve as a basis for exploring mechanisms of plasticity in the developing central nervous system.
A method for quantitative histological evaluation of neural cell populations
Authors: Duncan Gary H. , Gregg John M. , Galich John W. 
Published: February 2005

AbstractIn an attempt to facilitate quantitative analysis of neural peri‐karya, an inexpensive system of gridded coverslips has been developed to permanently map sections of tissue on microscopic slides. Utilizing common photographic copying techniques with Kodalith film, a mylar coverslip is produced which is imprinted with a grid of known dimensions. The exact scale of the grid can be varied precisely for compatibility with a particular field of magnification. The versatility and economy of this technique make it useful in many microscopic studies requiring superimposition of discrete landmarks.
Serous cysts of the aging guinea pig ovary I. Light microscopy and origin
Authors: Quattropani Steven L. 
Published: February 2005

AbstractOvaries from guinea pigs of different ages have been examined by light microscopy. Serous cysts measuring between 1 mm and 2.5 cm are present in all animals over one year of age. The cysts are fewer in number and size at six months, are least developed at ten weeks and are not apparent in the nearterm fetus. The cysts arise from the rete ovarii. They are lined with a simple cuboidal to columnar epithelium composed of cells bearing solitary cilia or tufts of cilia. The structure and origin of these cysts is discussed and compared with what is known of the human serous cystadenoma.
Development of neural elements in apical portions of cat primary and permanent incisor pulps
Authors: Johnsen D. C. , Karlsson U. L. 
Published: February 2005

AbstractPulp development was studied with light and electron microscopy in apical portions of cat primary and permanent incisors at various stages of development in order to qualitatively assess hypothesized differences during maturation. Primary and permanent tooth pulps passed through similar stages up to when the primary teeth began to resorb. At that point permanent tooth pulps continued to develop in complexity relative to myelinated axons and developed thin epineurial sheaths. Although the stages were similar in several regards, the time needed by the permanent tooth pulps to reach each stage was considerably greater than for the primary tooth pulps. It is of interest that the young permanent teeth had only a small portion of their final complement of nerves in spite of their relatively complete development.Individual axons, especially myelinated axons, appeared more immature in younger primary and permanent teeth. This suggests a less mature sensory capability for erupting primary teeth as compared to fully developed primary teeth as well as for erupting and young permanent teeth compared to old permanent teeth.
Light and electron microscopic histochemistry of the serous secretory granules in the salivary glandular cells of the mongolian gerbil (Mongolian meridianus) and rhesus monkey (macaca irus)
Authors: Ichikawa Misao , Ichikawa Atsushi 
Published: February 2005

AbstractLight and electron microscopic histochemistry was carried out on the serous secretory granules of the parotid acinar and sublingual demilunar cells of the Mongolian gerbil. These are bipartite in structure with a central dense core and a rim of lower density. Light microscopic techniques included staining of sections with Alcian blue and PAS reaction before and after sialidase digestion. PA‐methenamine silver, dialyzed iron, colloidal thorium and ruthenium red reactions for mucosubstance were compared on control and pronase digested materials. The results obtained have been interpreted to indicate that the peripheral rim of the granules contained mainly sialomucin whereas the central dense core was rich in protein. Freeze‐etched replicas and frozen thin sections of the gerbil salivary glands revealed the bipartite substructure of the granules to be a consistent structure regardless of specimen preparation procedures.The secretory granules in the serous acinar cells of the monkey submandibular gland which also have a central dense spherule and a rim of lower dense matrix were tested in the same way with the PA‐methenamine silver method. A positive reaction was limited to the rim of lower density matrix, indicating that this granular matrix is rich in carbohydrates in contrast to an unstained dense central spherule which is digested with pronase. Morphological and cytochemical similarities of the granule content between species are compared.
Secretion of granules by the luteal cells of the sheep and the goat during the estrous cycle and pregnancy
Authors: Gemmell R. T. , Stacy B. D. , Nancarrow C. D. 
Published: February 2005

AbstractThe fine structure of luteal tissue from sheep and goats at the mid‐stage of the estrous cycle and during pregnancy was examined. At the mid‐stage of the estrous cycle, when the corpus luteum of both species is secreting progesterone, the ultrastructure of the luteal cells is similar in that granule secretion is prevalent. In late pregnancy, the corpus luteum of the sheep produces very little progesterone and there is an absence of granule secretion. In the pregnant goat, the production of progesterone from the corpus luteum is high and there is plentiful evidence of granule formation and secretion.
Sarcoplasmic reticulum in the conducting fibers of the dog heart
Authors: Rybicka Krystyna 
Published: February 2005

AbstractThe ultrastructure or sarcoplasmic reticulum (SR) was studied in the conducting fibers of the dog heart. A dense network of sarcoplasmic tubules occurred in well preserved cytoplasmic areas. Some of the tubules extended into large sacs filled with finely filamentous material. The sacs often appeared in subsarcolemmal apposition connected to the sarcolemma by electron dense projections. The flattened cisternae of SR occurred beneath the sarcolem‐ma in the myofibrillar region of the cell. Long flattened cisternae only partially apposed to the sarcolemma were quite common in one specimen. Sarcoplasmic reticulum was continuous throughout the interfibrillar spaces surrounding each myofibril. At the level of the Z‐line the SR formed a quasi tubular flattened structure surrounding the Z‐line and closely adhering to it.
Differentiation and migration of endoderm in the rat and mouse at implantation
Authors: Enders Allen C. , Given Randall L. , Schlafke Sandra 
Published: February 2005

AbstractThe initial differentiation of endoderm at the time of onset of implantation, and the subsequent rapid differentiation of visceral and parietal endoderm were studied in the rat and mouse. Transmission electron microscopy illustrates the reorientation and loosening of embryonic cell mass cells during implantation, as well as cytological evidence that endoderm cells have differentiated. Using scanning electron microscopy, parietal endoderm consists of individual stellate cells with numerous peripheral branching filopodia. As these cells migrate abembryonically, the rest of the embryonic cell mass becomes recom‐pacted. The visceral endoderm proliferates and forms a columnar epithelium which has the cytological characteristic of an absorptive epithelium and is able to ingest exogenous proteins. Thus, by 24 hours after implantation, the two endo‐dermal derivatives have assumed widely diverse shapes and different types of associations and rates of replication, and are probably performing different functions.
A cytological study of plasma membrane modifications, intercellular junctions, and endocytic activity of amniotic epithelium
Authors: King Barry F. 
Published: February 2005

AbstractThe purpose of this study was to examine some cytological features of guinea pig amniotic epithelium which may be related to epithelial permeability. In addition to fine structural studies, the amnion was stained with ruthenium red to demonstrate the glycocyalyx and exposed to an exogenous protein (peroxidase) to ascertain some of the permeability characteristics of the intercellular junctions. The apical microvillous border had a distinct glycocalyx of filaments 3‐5 nm in diameter and up to 0.3 μm in length. These filaments stained with ruthenium red as did a narrower zone of glycocalyx adjacent to the outer leaflet of the plasma membrane. Epithelial cells were joined laterally by numerous desmosomes and by tight junctions; no evidence of a classical junctional complex was observed. When cells were exposed to ruthenium red or peroxidase, the tracer was impeded in its penetration between cells, probably by tight junctions. The presence of tight junctions indicates that the intercellular space is not continuous from the amniotic cavity to the underlying connective tissue, and undoubtedly the junctions play a role in controlling transepithelial permeability. The experiments with peroxidase also demonstrated the capacity of the cells to endocytose protein, especially at their lateral and basal surfaces. Late in gestation, increasing numbers of cells underwent cytological changes similar to cells undergoing keratinization. These changes included the disappearance of most of the cell organelles and the thickening of the plasma membrane by the addition of an electron‐dense layer to the inner (cytoplasmic) leaflet. The apparent keratinization of cells may result from increased abrasive trauma caused by the fetus or may be related to accumulation of various waste products in the amniotic fluid. In any event, the cytological modifications, especially of the plasma membrane, may indicate a change in cell permeability properties late in gestation.
The effects of vitamin B6 deficiency on the bone marrow of the rat1
Authors: Cassel Susan , Robson Linda , Rosse Cornelius 
Published: February 2005

AbstractBone marrow from adult rats fed a vitamin B6 deficient diet for two weeks was found to have reduced numbers of neutrophils, erythroid cells and small lymphocytes. The numbers of transitional cells were not reduced. Since the small lymphocyte population in the bone marrow consists of B cells and null cells in approximately the same proportion, it was concluded that both cell types were reduced as a result of the deficiency. A complete recovery in the cellularity of the bone marrow was brought about by returning the vitamin B6 deficient animals to a normal diet for four weeks. Other effects of the two‐week vitamin B6 deficient diet included a failure to gain weight, a decrease in thymus weight and a reduction in the numbers of white blood cells in the peripheral blood. All of these defects were corrected after the animals had been fed a normal diet for four weeks.
Ultrastructure of the anterior medial glands of the rat nasal septum
Authors: Tandler Bernard , Bojsen‐Møller Finn 
Published: February 2005

AbstractThe anterior medial glands lying in the submucosa of the rat nasal septum were studied by light and electron microscopy. The glands consist of a single long duct, which is studded with numerous solitary acinar formations connected perpendicularly to the main duct by short intercalated ducts. Proximal acini (those furthest from the stoma of the main duct) consist of typical serous cells with many dense secretory granules and an extensive rough endoplasmic reticulum. The most distal acini consist of cells whose major feature is the enwrapment of each mitochondrion by a cisternal profile of rough endo‐plasmic reticulum. Myoepithelial cells are absent from proximal acini, but are abundant on distal acini. Intracellular nerve terminals are extremely common, particularly in distal acini. The main ducts resemble, to a degree, the striated ducts of salivary glands.