bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ependymal cells of the filum terminale in fish (poecilia sphenops) adapted to freshwater and saltwater: Electron microscopic study
Authors: Kriebel Richard M. 
Published: February 2005

AbstractThe ependymal lining of the central canal of the filum terminale and spinal cord in the vicinity of the caudal neurosecretory system in P. sphenops was examined in this study. Two general cell types based on shape and location were observed in the ependymal lining: cuboidal ependyma located in dorsal aspects of the filum terminal and columnar to pseudostratified ependymal cells found in ventrolateral and ventral aspects of the filum terminale. Comparison of the ependymal lining was made in animals adapted to saltwater and freshwater. In animals adapted to saltwater there was an increase in the basal infoldings of the cell membrane of the dorsal cuboidal ependyma. Infolding of the basal cell membrane is a phenomenon shared by cells known to participate in transport of electrolytes. Since a possible functional relationship between the ependyma of the third ventricle and median eminence has been shown, in future studies on the osmoregulatory function of the caudal neurosecretory system the ependymal lining of the central canal in this region should be considered.
Ultrastructural immunocytochemistry of nascent albumin topology: Proposed cytosolic folding and membrane transit of the protein
Authors: LeBouton A. V. , Masse J. Peters 
Published: February 2005

AbstractThe relationship of nascent albumin and hepatocyte organelles was studied with the immunoperoxidase reaction in rats given various drugs to alter cellular albumin content. Colchicine was used to increase intracellular albumin. Cycloheximide inhibited synthesis but allowed nascent albumin to remain with its ribosome of origin. Puromycin also inhibited synthesis but released albumin from its ribosome. There was no difference in the appearance of attached ribosomes in hepatocytes from saline‐injected rats and those given colchicine or cycloheximide. In these cases, membranes of the endoplasmic reticulum were consistently decorated with ribosomes positive for the presence of albumin antigenicity on their cytosolic surface. The cisternal and cytosolic compartments were negative. The situation after puromycin was different. Here the membranes appeared to be denuded of ribosomes and reaction product, indicative of albumin, was present only on the lumenal surface. To determine whether puromycin had caused the release of ribosomes, sections from puromycin‐treated cells were stained nonspecifically with uranyl acetate. This showed that the normal amount of ribosomes was still bound but that they could not be seen when a probe specific only for albumin was used. It appears that nascent albumin can associate with its ribosome within the cytosol. Also, apparently after albumin passes through the membrane of the rough endoplasmic reticulum, it remains attached to its lumenal surface. A model incorporating cytosolic folding of albumin followed by its entropic membrane transit is presented.
Electron microscopic studies of rat sperm heads treated with urea, dithiothreitol, and micrococcal nuclease
Authors: Sobhon Prasert , Thungkasemvathana Pornpilai , Tanphaichitr Nongnuj 
Published: February 2005

AbstractUrea and dithiothreitol can decondense the chromatin in some of rat sperm heads. By this treatment, we have observed that in the nuclei of rat sperm the chromatin is organized into two morphologically distinct portions, namely: the compact chromatin rods of about 450 to 1,000 Å thick, and the interlacing fibers about 250–290 Å in thickness. When these treated sperm are further digested with micrococcal nuclease, the small fibers disappear, whereas the chromatin rods are still present in the “urea‐nuclease pellet.” From the available evidence, we suggest that the chromatin rods represent the highly packed nucleoprotamine, whereas the small fibers represent the more loosely organized nucleohistone.
Shunting in renal microvasculature of the rat: A scanning electron microscopic study of corrosion casts
Authors: Casellas D. , Mimran A. 
Published: February 2005

AbstractWe reinvestigated the still controversial existence of arterial pathways by‐passing glomeruli within kidneys of rats from weaning to more than 12 months old (i.e., body weight ranging from 39 g to 643 g). For this purpose, the arterial injection of microspheres 7.5 μm to 17 μm in diameter was combined to corrosion‐replication of the arterial bed of a vasodilated perfused kidney preparation. This procedure allowed easy detection of arterial by‐passes with light microscope and detailed observation with scanning electron microscope. Our results clearly demonstrate the existence of various categories of arterial by‐passes throughout renal cortex regardless of age. Some of them had never been described before. These vascular by‐passes were found with increased frequency from superficial to juxtamedullary cortex. In the latter area, frequency was not agedependent, and approximately 10% (range 4–22%) of juxtamedullary glomeruli were involved. Data derived from previous microsphere studies would suggest that these structures are (partially) nonfunctioning in basal physiological conditions, but more information is needed to assess their possible functional role in the rat.
Autoradiographic demonstration of ipsilateral and contralateral sensory nerve endings in cat dentin, pulp, and periodontium
Authors: Byers M. R. , Matthews B. 
Published: February 2005

AbstractIn order to determine the location of sensory nerve endings in cat teeth, 3H‐proline and 3H‐leucine were injected into the left trigeminal ganglion of eight cats aged 6.5–10 months; 24 hours was allowed for axonal transport of radioactive protein to dental nerve endings, and the endings were then detected by autoradiography. The pulps of most ipsilateral (left) teeth contained some labeled axons. These axons ended in the odontoblastic layer and predentin of roots and crown; at the tip of the pulp horn of each cusp, nerve endings also extended as far as 150 μm into dentinal tubules.Labeled nerve endings were extremely rare in contralateral (right) teeth; only one tooth of 83 studied (eight cats) contained heavily labeled axons, and one other had faintly labeled axons. Both labeled contralateral teeth were central maxillary incisors. Their labeled axons were unbranched in the root and arborized in the crown to end among odontoblasts and many adjacent dentinal tubules.Labeled periodontal nerve endings were most numerous in the apical one‐third of the ligament, with some endings extending as far as the gingiva. The nerve endings in the periodontal ligament were often clustered and appeared to end freely between the collagen bundles; their radioactivity varied in the same way as that of pulp nerves in the adjacent root.
Surface coat material associated with the cells of the developing lens vesicle in the chick embryo
Authors: Van Rybroek John J. , Olson Mark D. 
Published: February 2005

AbstractRuthenium red (RR) and cetylpyridinium chloride (CPC) were used to demonstrate the distribution of cell surface coat material (SCM) on the free epithelial surface of the developing lens vesicle in stages 14–17 (50–64 hours) chick embryos. Observations were made by light microscopy and transmission (TEM) and scanning (SEM) electron microscopy. A progressive increase in SCM is observed on cellular apices within the epithelium of the lens vesicle by means of RR staining, particularly at the margins of the aperture which are the sites of presumptive fusion. In contrast, a relatively thin layer of SCM persists on the adjacent surface ectoderm. Ruthenium red‐positive SCM extends across the aperture of the lens vesicle prior to initial contact between the advancing epithelial surfaces. The presence of abundant SCM is interpreted as a possible significant prerequisite to invagination and to epithelial adhesion and fusion prior to detachment of the lens from surface ectoderm. When CPC is added to the fixative, a flocculent precipitate over the aperture of the lens visicle and an associated band of modified surface ectoderm which extends ventrally from its lower margin are observed. The modified ectoderm and associated SCM likely represent a presumptive region of active coordinated cellular migration.
A light and electron microscopic study of the innervation of pulmonary arteries in the cat
Authors: Knight David S. , Ellison Jeffrey P. , Hibbs Richard G. , Hyman Albert L. , Kadowitz Philip J. 
Published: February 2005

AbstractNerve terminal‐smooth muscle relationships were studied in pulmonary arteries of the cat using 5‐hydroxydopamine to help differentiate adrenergic and nonadrenergic terminals. There was a periarterial plexus of nerves in the walls of pulmonary arteries that extended into the lung to innervate even small arteries having a single layer of smooth muscle cells. Adrenergic nerves surrounded all arteries and extended into the tunica media of the large arteries. There were also apparent cholinergic nerves around the pulmonary arteries, although this was confirmed by electron microscopy for medium‐ and small‐sized arteries only. The relationships of nerve terminals to smooth muscle cells in pulmonary arteries suggest that release of norepinephrine by adrenergic terminals can produce both decreased compliance and increased resistance in the pulmonary vascular bed, and that acetylcholine released by cholinergic terminals may act directly on vascular smooth muscle or on adrenergic terminals to modulate release of norepinephrine. These results suggest that both sympathetic and parasympathetic nerves may have a regulatory role in the pulmonary circulation.
A model of the inguinal canal
Authors: Jacobs John J. , Alvarado Donald M. 
Published: February 2005

AbstractMedical students often find it difficult to conceptualize and learn the anatomy of the inguinal region and canal. A model of the inguinal canal, appropriate for lecture and laboratory presentations, has been used for many years by one of the authors (J.J.J.), and based on student and staff feedback, is judged a successful visual learning aid. This paper outlines a step‐by‐step procedure for constructing the model out of plexiglass and colored, felt‐tipped marking pens.
Ultrastructural localization of nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and cytidine monophosphatase (CMPase) in the Golgi apparatus of early spermatids of the rat
Authors: Clermont Y. , Lalli M. , Rambourg A. 
Published: February 2005

AbstractAt the early steps 3–7 of spermiogenesis the hemispherical Golgi apparatus elaborates and is closely associated to the acrosomic system which grows at the surface of the spermatid's nucleus. It shows two distinct zones, a cortex made up of flattened saccules and related membranous tubules, and a medulla containing various types of vesicular profiles. The various components of the cortex of the Golgi apparatus were tested for their reactivity to three phosphatases. Nicotinamide adenine dinuclèotide phosphatase activity (NADPase, Smith, 1980) was observed in the middle two to six saccules in the stack with a midsaccule being more reactive than the saccules above and below. A weak and spotty reaction was also noted in the remaining saccules on the trans‐face of the stack and in the thick elements making up the GERL on the trans aspect of the stacks of saccules. Thiamine pyrophosphatase activity (TPPase, Novikoff and Goldfisher, 1961) was found in one or two saccules on the trans‐face of the stacks but was absent from the other Golgi components. Cytidine monophosphatase activity (CMPase, Novikoff, 1967) was observed in the GERL, in vesicles of the medulla and in the developing acrosomic system. In the intersaccular regions of the cortex the branching membranous tubules showed the same reactivity for the phosphatases to that of the saccules to which they are connected. ER cisternae associated with the Golgi apparatus, anastomotic membranous tubules seen in the peripheral Golgi region, small vesicles, as well as the first saccule on the cis‐face of the stacks were all negative for the three enzymes studied. These data indicated that in the cortex of the Golgi apparatus there were several distinct compartments that could be distinguished on the basis of structural and cytochemical features.
Fiber contribution from the mesencephalic nucleus of the trigeminal nerve to the trochlear nerve in the cat: A histological quantitative study
Authors: Sherif M. F. , Papadopoulos N. J. , Albert E. N. 
Published: February 2005

AbstractThe fiber connections between the trigeminal mesencephalic nucleus and tract and the trochlear nerve root of 15 cats were examined after silver impregnation of the pontomescencephalic region of the brains. The results revealed that: (a) some of the mesencephalic root fascicles join the trochlear root, (b) some of the mesencephalic root cells contribute their processes to the trochlear root, and (c) some mesencephalic cells are found amidst the fibers of the trochlear nerve during its intrabulbar course. The fibers of the trochlear nerve were counted at certain preselected sites before and after crossing the mesencephalic nucleus. The statistical data obtained indicated that the trigeminal mesencephalic root contributes 4–10% of the fibers of the trochlear nerve, before it crosses the mesencephalic nucleus.
An electron microscopic study on the extraocular muscles of a lamprey, Lampetra japonica
Authors: Nakao Taisuke , Aoki Shinichi 
Published: February 2005

AbstractThis paper reports an EM study on the observations of the extraocular muscles of the lamprey, Lampetra japonica. Individual muscles consisted of numerous subunits, each being surrounded by a common external lamina and containing two, S and F‐types, of muscle fibers. A subunit contained an average of 8.25 muscle fibers consisting of 5.58 S‐type fibers and 2.67 F‐type fibers. In a rectus anterior muscle, the total number of the S‐type fiber was 852, the average cross‐sectional area being 144 μm2. The total number of the F‐type fiber was 397, the average cross‐sectional area being 300 μm2. The S‐type fiber was characterized by the arrangement of myofibrils as a single layer in the cortical sarcoplasm as well as by the development of peripheral couplings. The F‐type fiber was characterized by the presence of central myofibrils in the juxtanuclear sarcoplasm in addition to peripheral myofibrils and by the development of the T‐system and triads at the level of the Z line. M lines appeared distinct in the F‐type fibers and less distinct in the S‐type fibers. Muscle fibers within individual subunits were separated from each other by a space about 20 nm, but no membrane specializations such as gap junction or desmosome have been determined to exist between adjacent muscle fibers.
Restricted mobility and endocytosis of anionic sites on newborn rat jejunal brush border membranes
Authors: Jersild Ralph A. 
Published: February 2005

AbstractThe distribution and mobility of anionic sites on the microvillous surface of newborn rat jejunal absorptive cells were studied using polycationic ferritin (PCF) as a visual probe and were compared with anionic sites previously described for adult jejunum. Segments from 5‐ to 26‐day‐old rats were incubated in PCF for 5 minutes either before or after fixation for electron microscopy. From days 5 to 20, anionic sites were distributed diffusely along the lengths of the microvilli and did not show random translational mobility. In contrast, microvilli examined from animals at weaning (21 to 26 days) resembled those from adults in which most binding sites were capable of lateral mobility and were induced by PCF to cluster into discrete patches. The diffuse pattern was altered by cortisone administration, paralleling a premature reduction in the endocytic apparatus of the cell.The difference in mobility of anionic sites with age coincides with differences in absorptive function. Evidence is presented showing that in the neonate binding of PCF to the microvilli was followed with time by endocytosis into an apical system of tubules for intracellular transport, incorporation into coated vesicles, and release through the lateral cell surface. The results suggest that endocytosis is accomplished by a mechanism that includes a directionally controlled movement for the selective internalization of PCF binding sites from the membranes of the microvilli to those of the tubular cytoplasmic channels.
Endoderm/mesoderm multiplication rates in stage 5–12 chick embryos
Authors: Rosenquist Glenn C. 
Published: February 2005

AbstractMultiplication rates for the endoderm/mesoderm layer of the head‐process to 17‐somite‐stage chick embryo were studied by implanting essentially identical transplants labeled with tritiated thymidine into paired recipient embryos. One recipient was fixed as soon as the transplant had healed (after 30 min) and the other was reincubated an additional 3.5 to 22.5 hr; the ratios of labeled cells in the paired embryos provided points on a graph that indicated that doubling of endoderm/mesoderm cells in head‐process‐stage chick embryos occurs at approximately 4.0 and 17.2 hr of reincubation.
Preliminary observations on the role of the mesonephros in the development of the adrenal cortex
Authors: Upadhyay Shakti , Zamboni Luciano 
Published: February 2005

AbstractThe interrelationship between mesonephros, adrenal cortex, and gonads was studied in 28‐ and 31‐day old sheep fetuses by means of light microscopy on plastic sections. At these stages, the adrenal cortex is just beginning to develop and the mesonephros is undergoing involution; its regression is accompanied by mobilization of cells from the glomerulus of a peculiar nephron situated in the proximal third of the organ, and referred to as “giant” because of its large size. The mobilized cells egress from this glomerulus organized in trabeculae, some of which reach the cranial extremity of the adrenal cortex while others coalesce into a prominent cellular formation which extends uninterrupted toward and into the developing gonads. In previous studies we have shown that the mesonephric cells which colonize the gonads differentiate into sustentacular and interstitial steroidogenic cells; the presence of an analogous cellular migration from the mesonephros to the adrenal cortex now suggests that also the adrenal cortical cells may be of mesonephric origin.
Third ventricle suprachoroidal cells
Authors: Kemali Milena 
Published: February 2005

AbstractUsing transmission electron microscopy two types of cells on the choroid plexus of the third ventricle of the frog Rana esculenta have been located. They lie on the microvilli and cilia of the choroid epithelium. Their free surface is in contact with the cerebrospinal fluid. One type, Kolmer‐like, has large, dense bodies in its cytoplasm. The cytoplasm of the other type is completely filled by large, ovoidal structures which have a limiting membrane and a polymorphic filamentous content. Their functional significance is unknown.
Vascular turnover of a continuously growing organ: The rat incisor
Authors: Pitaru S. , Michaeli Y. , Zajicek G. 
Published: February 2005

AbstractThe vascular tissue supplying the pulp of the continuously growing and developing rat incisor was quantitatively analyzed in six female rats, weighing approximately 200 gm each. One hour after a single administration of 3H‐TdR, 1 μCi/gm body weight, the rats were sacrificed and the lower left jaws excised and processed histologically. Every 20th section was evaluated for venular and arterial count, endothelial cell count, and percentage of labeled endothelial cells. It was found that the proliferative capacity of the vascular tissue of the rat incisor is confined to its most apical 3.0 mm‐a zone defined as the vascular progenitor compartment. Daily production of endothelial vein cells and of veins within the progenitor compartment were calculated to be 7,392 cells/day and two veins/day, respectively. Generation time of these cells was found to be 3.56 days.Endothelial cell production within the progenitor compartment provides for the formation of new vessels and for the enlargement and elongation of existing ones. The vessels originating within the progenitor compartment move in an incisal and centripetal direction, while simultaneously undergoing a continuous process of aging, until their ultimate disintegration.
Fine structural criteria of prolactin cells identified immunohistochemically in the male rat
Authors: Nogami Haruo , Yoshimura Fujio 
Published: February 2005

AbstractImmunoreactive prolactin (PRL) cells in the adult male rat pituitary were observed by light microscopy to be scattered throughout the gland without special localization but sometimes to form small clusters consisting of five to ten cells. The cells had oval, polygonal, and cuplike shapes. Using the “superimposition technique,” the fine structural properties of the PRL cells were examined on ultrathin sections just adjacent to the thick plastic section for immunostaining. Four cell types were distinguished: (1) oval, polygonal, and elongate cells with only small spherical granules, 130–200 nm in diameter; (2) oval or polygonal cells with both medium‐sized spherical granules (250–300 nm) and about same size of polymorphic granules; (3) polygonal cells containing only large polymorphic granules (300–700 nm in maximal diameter); (4) cup‐shaped PRL cells with spherical and small polymorphic granules. Furthermore, the prolactin immunoreactivity of these cell types was confirmed by the electron immunohistochemistry. Type 1 cells resemble, in fine structure, Kurosumi‐Oota LH‐gonadotrophs, but the former are not stained with anti‐rat LHβ serum, but with anti‐rat PRL serum. Although the functional relationship between these four types of cells is still unclear, it is concluded that the polymorphic shape of the granules is not necessarily an absolute criterion for identification of the PRL cell in the male.
Effects of fluorodeoxyuridine on the developing inner ear of the rat
Authors: Khan Khalid M. , Marovitz William F. 
Published: February 2005

AbstractThe inner ear in rats develops from the surface ectoderm on day 8 of a 22‐day gestational period. Labeled thymidine incorporation studies have indicated that in the developing inner ear most of the cells undergo terminal mitosis between gestational days 13 and 15. During this period the developing inner ear would be particularly vulnerable to environmental hazards. To test this hypothesis, pregnant rats were given a single intraperitoneal injection of 5‐fluoro‐2′‐deoxyuridine (FUdR), an antimitotic substance, on gestational days 12 to 16. The rats also received one injection of 3H‐thymidine 1 h prior to the removal of the fetuses. The animals were killed after various time intervals following the treatment, and the otocysts or inner ears were prepared for morphologic observations and biochemical assays. The cells in the inner ear of rats exposed to FUdR exhibited pyknotic nuclei and chromatolytic degeneration, and they eventually died. By 4 h after the administration of FUdR, pyknotic nuclei were seen in the antiluminal zone of the otic epithelium, and there was a substantial decrease in the number of the otic cells. This decline in cell number was seen until 24 h after treatment. However, the inner ears from the fetuses exposed to FUdR during gestational days 12–15 showed complete recovery from the toxic effects of the drug when examined on day 21 of gestation. The phenomenon of programmed cell death observed in the developing inner ear of the rat indicates that more cells are produced during the earlier stages of development than are required for the definitive adult structures. This phenomenon may represent an important protective feature. The redundant production of cells perhaps allows the developing otocyst to respond to an environmental stress by subtotal destruction of cells from the pool of undifferentiated cells, resulting in relatively fewer congenital anomalies of the inner ear.