bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, intracellular transport, and release of secretory protein in the seminal vesicle of the rat, as studied by electron microscope radioautography
Authors: Flickinger Charles J. 
Published: February 2005

AbstractThe seminal vesicle secretes a variety of substances into semen, ranging from small molecules to enzymes. The formation of protein components of the seminal vesicle secretion was studied in male rats following an injection of leucine‐3H. Samples of seminal vesicle were fixed and prepared for light and electron microscope radioautography at intervals ranging between four minutes and two hours after the injection. In specimens prepared four minutes after administration of the precursor, the majority of silver grains overlay the rough endoplasmic reticulum. At subsequent intervals, the proportion of grains over the endoplasmic reticulum declined, and peaks of labeling were observed sequentially over the Golgi apparatus and over secretory vacuoles. The maximal labeling of the Golgi apparatus was attained between 10 and 30 minutes after the injection. Secretory vacuoles acquired their greatest radioactivity 30 minutes following administration of the leucine‐3H. Labeled secretions began to appear in the lumen 30 minutes after the injection, and they became heavily labeled by one hour. The results suggest that secretory proteins are synthesized in the rough endoplasmic reticulum and transported rapidly to the Golgi apparatus where secretory vacuoles are formed. The secretory vacuoles migrate to the apical ends of the cells and discharge their contents into the lumen. The transport and release of secretory proteins in the seminal vesicle is unusually rapid and exceeds the rate in many other protein secreting cells, including that of the ventral prostate.
Chromatoid bodies in somatic cells of the planarian: Observations on their behavior during mitosis
Authors: Coward Stuart J. 
Published: February 2005

AbstractThe behavior of somatic cell chromatoid bodies in the planarian Dugesia dorotocephala during mitosis has been studied by electron microscopy. The relatively undifferentiated beta (progenitor) cells are the only somatic cells containing chromatoid bodies and also are the only dividing somatic cells. Somatic cell chromatoid bodies are known to disappear as differentiation takes place and reappear when dedifferentiation occurs. Interphase and prophase beta cells have juxtanuclear and peripheral cytoplasmic chromatoid bodies. There is no ultrastructural evidence to suggest they are derived from formed nuclear material. During metaphase and anaphase, the chromatoid bodies are segregated from the chromosomes and adjacent cytoplasm by cups of double membranes. By the completion of telophase, the chromatoid body size and number immediately adjacent to the nucleus is markedly decreased and extremely large chromatoid bodies may be found further out in the cytoplasm. These findings are compared to the behavior of germ cell chromatoid bodies and discussed in terms of their possible significance and function.
Proliferation of non‐neuronal cells in spinal cords of irradiated, immature rats following transection of the sciatic nerve
Authors: Gilmore Shirley Ann 
Published: February 2005

AbstractTransection of a peripheral nerve not only elicits changes in the injured neurons but also results in an increase in non‐neuronal cells, considered by most workers to be neuroglia, in the region of these neurons. Since studies in this laboratory have shown that the neuroglial population of spinal cords of immature rats can be reduced markedly by ionizing radiation, the present investigation was undertaken to determine if this reaction would occur in the irradiated spinal cord following transection of the sciatic nerve. In order to answer this question the sciatic nerve was sectioned unilaterally at 17 days of age (14 days post‐irradiation). Sham‐irradiated littermates served as controls. Light microscopic examination showed an increase in non‐neuronal cells throughout the gray matter on the side of axotomy in spite of a decreased neuroglial population in the 2,000 R and 3,000 R groups. These cells were scattered in the neuropil or were adjacent to injured neuronal perikarya in the anterior horn. Qualitatively similar reactions occurred in the 500 R and 1,000 R groups and in shamirradiated controls. Whether the magnitude of response is the same in all groups is currently under investigation, as are questions dealing with the origins of the reactive cells.
Mitochondrial pleiomorphism in sustentacular cells of Xenopus laevis
Authors: Kalt Marvin R. 
Published: February 2005

AbstractThe mitochondrial population of sustentacular cells in the testis of the amphibian, Xenopus laevis, has been examined by electron microscopy. Three distinct types of mitochondria have been observed. The first and most common mitochondrial type is a “typical” organelle with a rod‐like profile containing tubular to plate‐like cristae. The second mitochondrial form is characterized externally by irregular bulbous protrusions and internally by increased numbers of tubular cristae. The third mitochondrial type, which is usually ovoid in profile, has the most unusual internal membrane configuration, consisting of pleated folds pierced by regular rows of fenestrations. Mitochondrial type one is found in all sustentacular stages, mitochondrial type two first appears in sustentacular cells surrounding early spermatids, and mitochondrial type three is observed only in sustentacular cells surrounding spermatozoa. These observations indicate that discrete subclasses of mitochondria are present in sustentacular cells of Xenopus.
Specialized contacts of astrocytes with astrocytes and with other cell types in the spinal cord of the cat
Authors: Morales Ricardo , Duncan Donald 
Published: February 2005

AbstractAdult and half grown healthy male and female cats were used in this study. The white and gray matter of the dorsolateral region in the upper lumbar levels of the spinal cord were examined by electron microscopy after fixation by aldehyde perfusion and commonly used methods of embedding, sectioning and staining. The report is limited to description and illustration of specialized junctions of astrocytes. In addition to previously described astrocyte‐astrocyte gap junctions, astrocytes are connected by gap junctions to oligodendroglia cells and to neurons. Astrocytes also are connected with each other and with neurons by junctions characterized by wide (250 Å) gaps containing opaque gap material and by dense material adhering to the inner surfaces of the plasma membranes. The results suggest a morphological basis for adhesion and intercommunication between all adult derivatives of the embryonic neural tube.
Fine structure of the myotendinous junction and “terminal coupling” in the skeletal muscle of the lamprey, Lampetra japonica
Authors: Nakao Taisuke 
Published: February 2005

AbstractThe myotendinous junction in the skeletal muscle of adult lamprey Lampetra japonica was studied with an electron microscope. Numerous finger‐like sarcolemmal invaginations were present at the ends of muscle fibers to form the myotendinous junction. Parietal fibers of each muscle unit showed more closely distributed sarcolemmal invaginations than central fibers. Features of the myotendinous junction. Parietal fibers of each muscle unit showed more closely distributed sarcolemmal invaginations than central fibers. Features of the myotendinous junction generally conform to the accounts in the literature. The sarcolemmal invagination was covered on its sarcoplasmic aspect by the connecting filament layer and the dense amorphous attachment layer, and on the extracellular aspect by the intermediary layer and the external lamina with collagen fibrils arising from the myosepta. Sarcolemmal invaginations were sometimes seen to consist of a pair of sarcolemmas of adjacent muscle fibers within a muscle unit, which is characteristic to the myotendinous junction of lamprey. It is noteworthy that the connecting filament layer is much thinner than that, e.g., in the tadpole tail muscles (Nakao, '74). Furthermore, it is much thicker in the parietal fibers than in the central fibers. The sarcolemma of the terminal segment of the invagination frequently showed specific coupling with cisterns of the sarcoplasmic reticulum (terminal coupling). The external lamina is partially or completely deficient in the terminal segment of sarcolemmal invaginations which form terminal couplings so that collagen fibrils contained in the invagination appear to be in direct contact with the sarcolemma; however, definite relationships of collagen fibrils with the sarcolemma and the external lamina in the terminal segment of invagination still remain obscure. This type of coupling is considered to play a role in the coupling of excitation to contraction of muscle fibers as triads and diads.
Acute effects of ACTH on dissociated adrenocortical cells: Quantitative changes in mitochondria and lipid droplets
Authors: Zoller Lawrence C. , Malamed Sasha 
Published: February 2005

AbstractTo study the role of certain organelles in steroidogenesis, dissociated rat adrenocortical cells were incubated for two hours with ACTH at a concentration that induces a high level of steroid production. Sections of ACTH treated and untreated cells were photographed in the electron microscope, and morphometric analysis was undertaken to assess possible ACTH‐induced changes in total cell volume, volume density and numerical density of lipid droplets and mitochondria.There was no change in total cell volume. Lipid droplet volume density and numerical density decreased. Mitochondrial volume density did not change, but numerical density increased.The decrease in lipid droplet volume density indicates a rapid depletion of cholesterol for steroid production. This depletion is almost entirely due to the disappearance of lipid droplets, rather than to an overall diminution in their size, as shown by the decrease in lipid droplet numerical density. The mitochondrial data suggest that the adrenocortical cell has an adequate mitochondrial apparatus to respond to acute ACTH stimulation with increased steroid output without an increase in mitochondrial volume.
Cellular renewal in the enamel organ and the odontoblast layer of the rat incisor as followed by radioautography using 3H‐thymidine
Authors: Smith C. E. , Warshawsky H. 
Published: February 2005

AbstractRenewal of the cell populations of the incisor was studied in 100 gm male rats injected with a single dose of 3H‐thymidine and sacrificed at various times from one hour to 32 days after injection. Radioautographs showed that a cohort of labeled cells within the enamel organ, odontoblast layer, and pulp was carried passively with the erupting incisor from the apical end toward the gingival margin where the life cycle of these cells was terminated. Labeled cells in the upper and lower incisor, although traversing different absolute lengths, were found in approximately the same functional stage of their life cycle at similar times after the injection. Thus, by one and one‐half days labeled ameloblasts began inner enamel secretion. By 32 days labeled ameloblasts had traversed the entire maturation zone and were located at the gingival margin. Labeled odontoblasts followed closely the movement of labeled ameloblast. The mean rate of ameloblast migration was 567 μm/day on the upper incisor and 651 μm/day on the lower. For the odontoblasts this rate was 500 μm/day (upper) and 631 μm/day (lower). Finally, it was found that as the rat aged, the duration of the life cycle for epithelial and pulp cell populations of the incisor increased because of growth within the longitudinal axis of the tooth. It was concluded that the apical end of the incisor literally “grows backward” in the bony socket, and hence, the duration of the life cycle becomes greater simply because it takes cells longer to physically reach the gingival margin.
Distribution of lumbar and sacral afferent axons in submucosa of cat urinary bladder
Authors: Uemura Etsuro , Fletcher Thomas F. , Bradley William E. 
Published: February 2005

AbstractLumbar and sacral afferent axons in the submucosa of the urinary bladder were recognized by degeneration in seven cats subjected to spinal ganglionectomies. Of 2,935 observed terminating axon profiles, 145 were found degenerating. Lumbar afferent axons were 3.7 times more numerous than sacral afferent axons in the submucosa, a reversal of the ratio reported for the muscle coat of the bladder. Sacral afferent axons were evenly distributed to different regions of the bladder, but lumbar afferents were concentrated in the bladder neck. Apparent endings in the submucosa of the urinary bladder were principally free nerve endings. Synaptic vesicles were found in 57% of observed terminating axon profiles. The bladder neck had more terminating axon profiles of all kinds than other regions of the urinary bladder.
Anatomical data on the intracranial venous drainage of the tufted capuchin, Cebus apella linnaeus, 1758
Authors: Madeira Miguel C. , Watanabe Ii‐Sei 
Published: February 2005

AbstractThe venous channels responsible for the intracranial drainage were dissected in a series of 25 male and female adult tufted or brown capuchin monkeys (Cebus apella).It was found that Cebus have a venous arrangements fundamentally the same as in man, differing only in that: 1. the monkey has no inferior sagittal sinus, sphenoparietal sinus, and emissary parietal and condylar veins; 2. the occipital sinus is not in connection with other sinuses; 3. there are a sphenopetrosal sinus, a petrosquamous sinus, and an unpaired inferior cerebellar vein; 4. besides the internal jugular vein, there is additional intracranial drainage through the petrosquamous sinus and the postglenoid vein; 5. the superficial middle cerebral vein opens into the petrosquamous sinus; 6. the lingual and facial veins are not tributaries of the internal jugular vein; 7. there is a bilateral uniform division of the superior sagittal sinus at the confluence of the sinuses to drain equally into both transverse sinuses; 8. the vascular pattern appears to be quite stable; anatomical variations appear to be few and unimportant.
The growth of the chick retina after hatching
Authors: Morris Valerie B. , Wylie C. C. , Miles V. J. 
Published: February 2005

AbstractIn autoradiographs of the retina from two‐week old chicks injected with tritiated thymidine during the first week after hatching, the labelled cells were found mainly in the extreme periphery of the retina and the ciliary epithelium of the pars plana. The pattern of labelling in the extreme periphery resembles that observed (Fujita and Horii, 1963) in retinae exposed to tritiated thymidine during embryonic development. The mechanisms underlying the histogenesis of retinal cells during growth at the extreme periphery in young stages may be the same as those which operate during embryonic development.
Studies of the hemopoietic microenvironment. VIII andrenergic and cholinergic innervation of the murine spleen
Authors: Reilly Frank D. , McCuskey Robert S. , Meineke Howard A. 
Published: February 2005

AbstractNeurohistochemical techniques were used to confirm morphologically the distribution of adrenergic and cholinergic nerves to the splenic microvasculature. The results form the basis of this report.Using these methods, adrenergic innervation was observed only in the adventitia of arteries and arterioles. No cholinergic innervation was found in this site. No adrenergic or cholinergic innervation could be demonstrated to the channels of the red pulp, venules or veins. These data provided morphological evidence that in the murine spleen only splenic arteries and arterioles are innervated; and these have only an adrenergic innervation.
A proposed function for microridges on epithelial cells
Authors: Sperry David G. , Wassersug Richard J. 
Published: February 2005

AbstractMicroridges (MR), also called microvillar ridges, microplicae and cytoplasmic folds, have been noted on many epithelial surfaces. Several functions have been proposed for these structures. In the present study we examine the mechanical role that microridges may play in holding mucus to the lumenal surface of the esophagus in the trout Salmo gairdneri. Our findings support the hypothesis that the microridges help hold a protective coat of mucus to the epithelium. In addition, the complex curved or whorled arrangement of microridges appears to facilitate the spread of mucus away from goblet cells.
Anchoring device between Sertoli cells and late spermatids in rat seminiferous tubules
Authors: Russell L. , Clermont Y. 
Published: February 2005

AbstractNear the end of spermiogenesis, the late spermatids remain attached to the superficial layer of the seminiferous epithelium for an appreciable period of time (i.e., 3 to 4 days). The sickle‐shaped heads of the spermatids are embedded in an apical process of Sertoli cell cytoplasm which is connected to the rest of the cell by a narrow stalk. In the concavity of the head several long (2–3 μm) and very narrow (50 nm) tubular projections of the spermatid's plasma membrane invaginate the Sertoli cell cytoplasm. These tubular processes terminate by a bulbous swelling which may measure up to 1 μm in diameter. Along the process the plasma membrane of the Sertoli cell is closely apposed to the spermatid's membrane, the intercellular space being only 6–8 nm wide. In the Sertoli cytoplasm immediately surrounding the tubular portion of the structure there is an accumulation of filamentous material, while next to the bulbous extremity there are, at a short distance, smooth surfaced cisternae of endoplasmic reticulum. The whole structure was referred to as a tubulobulbar complex. These complexes, of which there are up to 24 per spermatid, appear as these cells complete their migration toward the apex of the Sertoli cells. They disappear just before the release of the spermatids in the lumen of the seminiferous tubule as a result of the fragmentation of the spermatid's plasma membrane followed by a resorption of the Sertoli plasma membrane. Morphological evidence suggests that the tubulobulbar complexes serve as anchoring devices that retain the spermatids at the surface of the seminiferous epithelium while their dissolution contributes in part to the process of spermiation. Similar tubulobulbar complexes were also formed by the plasma membranes of two adjacent Sertoli cells close to the Sertoli‐Sertoli tight junctions near the tubular limiting membrane.
The early stages of wallerian degeneration in the severed optic nerve of the newt (Triturus viridescens)
Authors: Turner James E. , Glaze Kathleen A. 
Published: February 2005

AbstractThe initiation of Wallerian degeneration in the severed optic nerve of the newt (Triturus viridescens) was very rapid and intense. Significant degeneration of nonmyelinated axons was observed as early as six hours after lesion (h.a.l.) and was almost complete by 48 h.a.l. Initial degeneration of non‐myelinated axons began in “extracellular digestion chambers” formed between burgeoning ependymoglial processes. The remaining fragments and debris were later phagocytized by surrounding ependymoglial processes.Many axons of myelinated fibers have degenerated as early as 6 h.a.l. However, the overall population of myelinated axons degenerates at a much slower rate than nonmyelinated ones, for many of them appear intact as late as 48 h.a.l.Some myelin sheaths show significant signs of degeneration by 6 h.a.l. Indeed, by this time a number of myelinated fibers have completely degenerated leaving only large vacuolated spaces in the nerve parenchyma. Swelling and vacuolization of the sheath are among the earliest signs of myelin degeneration.The ependymoglial cell response to optic nerve lesion is manyfold and dramatic. By 6 h.a.l. there are signs of burgeoning ependymoglial processes which begin to resemble scar formation (gliosis) by 48 h.a.l. The morphological evidence is consistent with the concept of an important phagocytic role of ependymoglial cells during the early stages of optic nerve degeneration.
Localization of actin and myosin in the rat oocyte and follicular wall by immunofluorescence
Authors: Amsterdam Abraham , Lindner Hans R. , Gröschel‐Stewart Ute 
Published: February 2005

AbstractThe distribution of actin and myosin in the rat ovary at different stages of postnatal development was studied by examination of cryostat sections treated with antibodies to chicken smooth muscle (gizzard) myosin or to chicken (pectoral muscle) actin and subsequently with fluoresceinated goat anti‐rabbit γ‐globulins. Staining with either antiserum revealed several layers of intensely fluorescent elongated cells within the theca externa, forming a coherent band around the larger Graafian follicles. In smaller follicles, this band of fluorescent cells was incomplete, and ovaries of immature (6‐day‐old) rats were devoid of strongly fluorescent cells. Corpora lutea contained only scattered fluorescent cells at their circumference. Sections of mature ovaries incubated with antibodies raised against striated (pigeon pectoral) muscle myosin generated no significant fluorescence. Large oocytes stained with either anti‐actin or anti‐smooth muscle myosin showed a thin fluorescent band just beneath the zona pellucida, suggesting that actin and myosin are associated with the oolemma. The distribution of the two antigens in serial sections of follicles coincided, suggesting that the same cells contained both actin and myosin. It is suggested that follicular growth and maturation is attended by the development of a smooth muscle layer in the theca and that contraction of this layer in response to catecholamines and/or prostaglandins may play a role in the extrusion of the oocyte. The rǒle of contractile elements in the oocyte remains to be elucidated.
Preparation of biological tissues for electron microscopy by freeze‐drying
Authors: Coulter H. David , Terracio Louis 
Published: February 2005

AbstractA dependable method for freeze‐drying tissues for electron microscopy has been developed. Thin slices of fresh tissue were frozen by bringing them into direct contact with a polished copper bar at liquid nitrogen temperature. The tissue was transferred to a copper specimen block equipped with a thermocouple and heating circuit for accurate control of the environmental temperature of the tissue, and evacuated in a glass freeze‐drier using clean high vacuum techniques for keeping the system free of hydrocarbons. The tissue was dried by increasing the temperature of the specimen block 10°C each hour while monitoring the rate of water removal from the tissue with a partial pressure analyzer. The dry tissue was fixed with OsO4 vapor, vacuum embedded in a low viscosity epoxy resin, sectioned, stained, and viewed with the electron microscope. Tissue processed in this manner exhibits excellent morphological preservation at both cellular and organellar levels without prefixation or the use of cryoprotective agents. The results of the experiments using the partial pressure analyzer indicate that small blocks of tissue can be dried in a short time at low temperature.