bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postnatal development of mitral cell perikaryon in the olfactory bulb of the rat. A light and ultrastructural study
Authors: Singh Dyal N. P. , Nathaniel Edward J. H. 
Published: February 2005

AbstractThe differentiation of the mitral cell perikaryon in postnatal rat olfactory bulb was studied with the light and electron microscope. At birth the mitral cell was distinguishable and occupied a definitive position in the mitral cell layer. The cell contained a large oval nucleus surrounded by a thin rim of cytoplasm. Ribosomes, free and clustered, were scattered in the cell cytoplasm. Rough endoplasmic reticulum was relatively scarce. The Golgi complexes were made up of stacks of smooth‐surfaced cisternae and associated vesicles. In certain cases the Golgi complexes projected into cellular processes. Mitochondria were present in all regions of the cytoplasm and contained well developed cristae. At the end of the first week, the mitral cell had developed significantly in size, and the cytoplasm contained well‐developed rough endoplasmic reticulum. The Golgi complexes were made up of several stacks of smooth‐surfaced cisternae with the association of vesicles and electron dense bodies. The apical dendrites o mitral cells at this periiod had increased significantly in length. Subsequently, during the second and third week, the rough endoplasmic reticulum and Golgi complexes became well developed. Associated with the Golgi complexes were electron dense lysosomal bodies. At three weeks and in older cells it was observed that dense lysosomal bodies. At three weeks and in older cells it was observed that dense lipofuschin granules increased significantly. It is suggested that the mitral cell matures and differentiates earlier than cells in the cerebral cortex.
Scanning electron microscopy of palatal mucosa maintained in organ culture: A method for three‐dimensional visualization of cell morphology
Authors: Bergenholtz Axel , Hallmans GöRan , Hanstrom Lennart 
Published: February 2005

AbstractA scanning electron microscopic (SEM) study of palatal mucosa maintained in organ culture (50% O2‐Eagle's MEM w/o serum) from 12 to 360 hours is presented. The morphological changes occurring in the explants during culture are illustrated and the findings are compared with those observed using transmission electron microscopy and light microscopy. The results confirm that cellular fine structure in epithelium and connective tissue is more easily visualized when SEM is employed following in vitro maintenance of explants as opposed to examination of fresh uncultured biopsies. The in vitro system used would appear to be applicable to studies designed to investigate the effect of various substances on cell proliferation and cell interactions.
Functional anatomy of lymph nodes. II. Peripheral lymph‐borne mononuclear cells
Authors: Kelly R. H. , Balfour Brigid M. , Armstrong J. A. , Griffith S. 
Published: February 2005

AbstractIn the rabbit a number of large mononuclear cells with ruffled surface membranes travel from the skin and superficial tissues of the leg, via the lymphatics, to the popliteal lymph node: they constitute 40‐50% of the total cell population in the afferent lymph. About 10% of these cells are actively phagocytic when tested in vitro and about 3% are found to contain Langerhans granules.After isotopic labelling the majority of lymph‐borne mononuclear cells can be detected within the regional node for at least 24 hours; most being located in the paracortex and a few in the interfollicular cortex. It is proposed that these cells, including those containing Langerhans granules, belong to the “mononuclear phagocyte system.”Possible functions of these lymph‐borne cells are discussed with particular reference to antigen transport.
Light and scanning electron microscopic observations of the effects of sublethal doses of methotrexate on the rat small intestine
Authors: Jeynes B. J. , Altmann G. G. 
Published: February 2005

AbstractThe small intestines of adult rats were examined by light and scanning‐electron microscopy after sublethal doses of methotrexate were injected at 5, 3 and 1 mg, respectively, per rat per day, for three days. Methotrexate inhibited mitosis and thereby disrupted the steady state system of the epithelium. Villi and crypts progressively diminished up to about four and one‐half days after the initial injection. Thereafter, recovery began and, by day 7, relatively normal morphology was restored. In the degenerative phase, the loss of crypt‐villus continuum was frequently observed, the former crypts forming cyst‐like structures. The columnar cells became flat and pleomorphic but epithelial continuity was maintained. Goblet cells apparently decreased in number. Paneth cells, especially in the ileum, appreciably increased in size and number. During the recovery phase, the cystic crypts apparently re‐established continuity with the villus epithelium. Size and proportion of all epithelial cell types returned to normal. Scanning electron microscopy showed villus fusion and the cellular pleo‐morphism and loss of microvilli during the degenerative phase. During recovery of the villi some alteration in orientation and shape remained as shown by scanning electron microscopy.
Fluoride‐induced mineralization within vacuoles in maturative ameloblasts of the rat
Authors: Kuhar Kenneth J. , Eisenmann Dale R. 
Published: February 2005

AbstractDense crystalline deposits appeared within vacuoles in rat maturative ameloblasts as a result of repeated injections of sodium fluoride. The crystals assumed varied arrangements but were always observed within intracellular vacuoles. The crystals resemble those of normal enamel and resist microincineration. They are readily dissolved by decalcification and leave behind an organic framework which matches the outline of the crystals. An experimental model is presented which may be useful in further studies of calcium transport, enamel matrix absorption or digestion of cellular debris.
The effect of marcaine on muscle and non‐muscle cells in vitro
Authors: Schultz E. , Lipton B. H. 
Published: February 2005

AbstractThe effect of the local anaesthetic Marcaine on muscle and non‐muscle cell types was examined using an in vitro assay. Each of the cell types examined (myotubes, myoblasts, fibroblasts and liver parenchyma) expressed morphological alterations when incubated in Marcaine‐medium. Myotubes were the most sensitive of the cells studied and exhibited several pronounced membrane structural changes after short incubation periods in Marcaine‐medium. The toxic effects of Marcaine were irreversible and the myotubes continued to degenerate despite being placed in fresh medium. Myo‐blasts and non‐muscle cells, however, demonstrated a rapid recovery when removed from the Marcaine‐medium. Since Marcaine is thought to compete with Ca++ for specific sites on cell membranes, it is proposed that the differential effects which were observed are dependent upon the level of calcium related activities being carried out by the cells.
Morphological studies on the adrenergic innervation of white adipose tissue
Authors: Slavin Bernard G. , Ballard Kathryn W. 
Published: February 2005

AbstractWhite adipose tissue was obtained from the mesentery, epididymis, omentum and subcutis of rats which were fed, fasted or fasted and then refed. Tissue samples were prepared using the glyoxylic acid method to detect adrenergic nerves by fluorescence histochemistry. Other tissue samples were fixed with an aldehyde solution containing sodium molybdate which is specific forcatecholamine granules in nerve terminals. Thin and serial thick sections (0.25–0.5μm) were viewed with a conventional electron microscope and with the high voltage electron microscope. With fluorescence microscopy it was found that most of the blood vessels except veins and venules were richly innervated. The most extensive branching of nerves down to the capillary level was found in the mesentery and epididymal fat of fasted‐refed rats. Relatively few adipocytes appeared to be innervated. With electron microscopy, nerve terminals were found distributed with most blood vessels including capillaries, and with some adipocytes. Only 2‐3% of all adipocytes were innervated by adrenergic nerves. It is suggested that in the adipose tissue sites studied the major adrenergic innervation is mainly for the supply of blood vessels.
Unusual features of the nuclear envelope in human spermatogenic cells
Authors: Chemes H. E. , Fawcett D. W. , Dym M. 
Published: February 2005

AbstractDifferent types of human germ cells show unusual features of the nuclear envelope. Spermatogonial nuclei demonstrate two kinds of modifications. The first one is a series of intranuclear flattened cisterns, parallel to each other and to the inner aspect of the nuclear envelope. The second one is a nuclear envelope protrusion into the cytoplasm occupied by a double membrane‐limited vesicle. Pores are found on the membrane of the vesicle facing the interior of the nucleus. In spermatocytes the nuclear pores are concentrated over certain areas and completely absent from others. In the regions where they are absent a single cytoplasmic cistern of rough endoplasmic reticulum is closely apposed to the outer membrane of the nuclear envelope. Early modifications of the nuclear surface appear in spermatids before the attachment of the acrosomic vesicle and may indicate an active role of the nuclear envelope in the morphogenesis of the acrosome. In round spermatids nuclear pores are absent from the area which is first related to the Golgi and later covered by the acrosomal cap. Single or multiple layers of cytoplasmic annulate lamellae are closely associated with the nuclear envelope over the pore rich areas. Frequently there are intranuclear accumulations of dense material adjacent to the annulate lamellae‐nuclear pore complex. The chromatoid body is usually present on the cytoplasmic side of this complex. In the elongating spermatids most annulate lamellae are free in the cytoplasm, often in relation with Golgi and chromatoid body remnants near the axial filament. Few stacks of annulate la‐mellae are noted adjacent to the pore rich nuclear regions. It is suggested that the described modifications are related to an active nuclear‐cytoplasmic interaction.
Testosterone and UVL‐B stimulation of epidermal melanocytes in rat scrotal skin
Authors: Glimcher Mark Edward , Wilson Michael J. , Szabo George 
Published: February 2005

AbstractThe effects of UVL‐B and/or testosterone replacement therapy are compared in normal and castrated rats in order to determine whether testosterone is required for UVL‐B (280‐315 nm) stimulation of melanogenesis in the testosterone‐dependent epidermal melanocyte system of the scrotal skin of black Long Evans rats. Testosterone is not a prerequisite for UVL‐B stimulation of melanocytes as in both castrates and normal animals the melanocytes respond to UVL‐B by increases in size, length and number of dendrites (dendriticness), and tyrosinase activity (intensity of Dopa reaction). Addition of testosterone to castrates does enhance the effects of UVL‐B. However, UVL‐B with or without testosterone cannot maintain normal melanogenesis in rats irradiated immediately after castration nor can it restore normal melanogenesis following long term castration. Both the amount of UVL energy/exposure and the number of exposures are important variables in stimulation of the epidermal melanocytes. Administration of a dose of UVL‐B to castrates in a single exposure is ineffective, while the same overall dose spread over several exposures increases the size and dendriticness of melanocytes. Testosterone and UVL‐B act synergistically in affecting melanogenesis although neither singly nor in combination are they able to fully restore normal melanogenesis.
Ultracytochemical localization of Na+,K+‐activated ATPase in chloride cells from the gills of a euryhaline teleost
Authors: Hootman Seth R. , Philpott Charles W. 
Published: February 2005

AbstractThe activity of the electrolyte transport enzyme, sodium, potassium‐activated adenosine triphosphatase (Na+,K+‐ATPase), in the gills of the pinfish, Lagodon rhomboides, increased markedly following transfer of fish from brackish water to seawater. Cytochemical localization of Na+,K+‐ATPase via its potassium‐dependent phosphatase (K+‐NPPase) activity in the branchial epithelium of pinfish adapted to seawater demonstrated that chloride cells are the major sites for the enzyme. Subcellularly, the heaviest depositions of reaction product were observed lining the cytoplasmic membrane surfaces of the labyrinth of anastomosing plasma membrane tubules that ramifies throughout the chloride cell cytoplasm. Enzyme activity was demonstrated also on the cytoplasmic surface of the apical crypt membrane and on the cytoplasmic surfaces of vesicles in the cytoplasm subjacent to the crypt. Deletion of potassium from the cytochemical incubation medium or inclusion of 10 mM ouabain abolished the reaction products associated with these membranes. The significance of these cytochemical results is discussed with reference to current hypotheses of chloride cell function.
Differences in mouse ovarian cells as distinguished by horseradish peroxidase labelling
Authors: Carron Christopher P. , Longo Frank J. 
Published: February 2005

AbstractThe extracellular space of mouse ovarian follicles and stroma contained horseradish peroxidase (HRP) reaction product one minute after intravenous injection of the tracer. In addition to pinocytotic uptake of the tracer, non‐vesicular staining with HRP reaction product, heretofore unrecognized, was noted in a variety of ovarian cell‐types. This diffuse staining was correlated with changes in cellular morphology suggestive of degeneration. These findings are discussed in relation to the composition of cell populations comprising follicles and ovarian stroma and alterations in cell function.
Further observations on tubulobulbar complexes formed by late spermatids and sertoli cells in the rat testis
Authors: Russell Lonnie D. 
Published: February 2005

AbstractThe present study extends earlier findings (Russell and Cler‐mont, '76) by describing additional details of the structure, relationships, distribution, origin, and fate of tubulobulbar complexes. Freeze‐fracture and thin section observations reveal few membrane associated particles and no appreciable cell coat in the membranes forming the tubulobulbar complex. The opposing plasma membranes of the complex do not appear to form a junction, although junctional formation might be expected by the close proximity (4.0 nm apart) of the Sertoli and spermatid plasma membranes. Sertoli filaments of the network which encircle the tubular portion of the complex measure 5.0‐7.0 nm across and appear to insert into the Sertoli plasma membrane. Tubulobulbar complexes initially form in association with a cell surface modification (bristle‐coated pit) of the Sertoli plasma membrane. The first tubulobulbar complexes develop large bulbous components (up to 2.5μm across), which soon lose connection with the spermatid and become incorporated into large phagocytic vacuoles (secondary lysosomes). As bulbs undergo dissolution, newly formed tubulobulbar complexes are observed to replace these structures. Thus, the data indicate that more than one generation of tubulobulbar complexes develop. Moreover, the tubular and bulbous portions of most dissociating complexes (as well as neighboring Sertoli lysosomes) show acid phosphatase activity. Near the time of sperm release, all complexes at the concave aspect of the spermatid head are resorbed. New tubulobulbar complexes, many lacking terminal bulbous dilations, form at the dorsal and lateral aspects of the spermatid head. These persist even after all ectoplasmic specializations and most Sertoli cytoplasm have been withdrawn from a position facing the spermatid head. The presence of tubulobulbar complexes just prior to the time of sperm release is in support of previous findings indicating that tubulobulbar complexes participate in anchoring the head of the late spermatid prior to sperm release. Past the zone of sperm release a few abnormally shaped cells, which had not been released with other spermatids of the same generation, display intact tubulo‐bulbar complexes. The persistence of these and other structures may be the means by which abnormally shaped spermatids are retained and prevented from traversing the male duct system.
Impregnation of soft biological specimens with thermosetting resins and elastomers
Authors: Hagens Gunther Von 
Published: February 2005

AbstractA new method for impregnation of biological specimens with thermosetting resins and elastomers is described. The method has the advantage that the original relief of the surface is retained.The impregnation is carried out by utilizing the difference between the high vapor tension of the intermedium (e.g., methylene chloride) and the low vapor tension of the solution to be polymerized. After impregnation, the specimen is subject to polymerization conditions without surrounding embedding material.The optical and mechanical properties can be selected by proper choice from various kinds of resins and different procedures, for example, by complete or incomplete impregnation. Acrylic resins, polyester resins, epoxy resins, poly‐urethanes and silicone rubber have been found suitable for the method.Excellent results have been obtained using transparent silicone rubber since after treatment the specimens are still flexible and resilient, and have retained their natural appearance.
Ultrastructure of the fetal rat anterior pituitary gland at term and during prolonged gestation
Authors: Anderson Judy E. , Thliveris James A. 
Published: February 2005

AbstractThe ultrastructure of the fetal rat anterior pituitary gland is described at term (day 22) and during experimentally prolonged gestation (days 23, 24, 25). The latter was achieved by daily subcutaneous injections of five mg progesterone to gravid females from the twentieth through the twenty‐fourth day. Using morphological criteria for classifying pituitary cells (Moriarty, '73), six different types were observed: thyrotrophs, gonadotrophs, corticotrophs, mammotrophs, somatotrophs and non‐granulated cells.During prolonged gestation (days 24 and 25 only), cells designated as cor‐ticotrophs revealed changes suggesting increased activity, i.e., proliferation and dilation of the endoplasmic reticulum, dilated Golgi membranes and a reduction of secretory granules. In addition, meconium staining, which is indicative of fetal distress, was also observed on days 24 and 25. The ultrastructural changes noted suggest an increase in corticotroph activity due to fetal hypoglycemia and hypoxia which are known to occur as a result of placental insufficiency during prolonged gestation (Roux et al., '64; Vorherr, '75; Thliveris, '76).
Response of periodontal ligament cells to orthodontic force: Ultrastructural identification of proliferating fibroblasts
Authors: Yee John A. 
Published: February 2005

AbstractThe morphologic response of periodontal ligament (PDL) cells in an area of tension created by orthodontic force has been assessed by transmission electron microscopy. Young adult male rats were sacrificed at 24, 48, 72, 96 and 120 hours following orthodontic stimulation. The earliest detectable response was the appearance of increased numbers of mitotic cells in the PDL at 24 hours post‐stimulation. The most significant ultrastructural feature of these cells was the presence of intracellular vesicles containing collagen microfibrils. These vesicles were identical to profiles present in interphase PDL fibroblasts involved in collagen phagocytosis associated with turnover of the ligament. Between 48 and 120 hours the alveolar bone surface in the region examined was characterized by the presence of newly generated osteoblasts and active bone formation. Intracellular collagen was never observed in osteoblasts. These observations suggest that at least a portion of the population of PDL cells which proliferate in response to orthodontic force represent functional ligament fibroblasts.
A novel technique for high resolution analysis of the cytoskeleton
Authors: Trotter John A. , Kelley Robert O. 
Published: February 2005

AbstractA new technique is described for producing and examining carbon‐platinum replicas of the cytoskeleton of cultured cells. This technique allows the individual components of the cytoskeleton to be visualized and positively identified in the transmission electron microscope, and also permits an analysis of the 3‐dimensional disposition of these components.
Fine structural studies on white adipocyte differentiation
Authors: Slavin Bernard G. 
Published: February 2005

AbstractThe differentiation of mammalian white adipocytes from prenatal through early postnatal periods was studied by light and electron microscopy in C57BL mice. Anatomical regions chosen for this study were the epididymal, mesometrial, mesenteric and inguinal fat pads. In each of these regions, adipocytes differentiated from fibroblast‐like cells (preadipocytes) characterized by an ovoid nucleus, profiles of rough endoplasmic reticulum, microtubules, microfilaments, spherical mitochondria, and small multiple lipid inclusions. Preadipocytes of the inguinal fat pad were first observed prior to birth (17–19 days), whereas, in the other anatomical sites, these cells were not observed until one to three days postnatally. As differentiation proceeded, and as the adipocytes assumed a spherical shape, there was a progressive decrease in the amount of rough endoplasmic reticulum and microfilaments concomitant with transient glycogen storage and an increase in the size of lipid droplets. Mature unilocular adipocytes were observed in the inguinal fat pads at three days of age. On the other hand, these cells did not appear until seven days after birth in the epididymal fat pad, mesometrium and mesentery. Regardless of the anatomical region studied, the differentiation of preadipocytes to adipocytes proceeded similarly. Preadipocytes could not be distinguished from fibroblasts morphologically within the fat depots studied. Adipocytes at the mid‐stages of differentiation and in all regions studied occasionally exhibited close intercellular contacts of varying morphology.
Ultrastructural localization of histones in epiphyseal chondrocytes
Authors: Wezeman Frederick H. 
Published: February 2005

AbstractEpiphyseal growth plate chondrocyte nuclei of growing rats were studied for histone content using the ammoniacal silver technique. This stain, which is specific for the demonstration of the arginine‐rich fractions of histones, revealed that growth plate nuclei vary in their histone content. Nuclei of cells of the proliferating zone revealed a significantly greater amount of postformalin ammoniacal silver deposit consistent with the presence of arginine‐rich histones.
Structure and function of the intestinal epithelial cells in the perch (perca fluviatilis l.)
Authors: Noaillac‐Depeyre J. , Gas N. 
Published: February 2005

AbstractAn ultrastructural study of the intestinal absorptive epithelium in perch (Perca fluviatilis) has shown that the perch intestine can be divided into three segments: the proximal segment, the middle segment and the distal segment. The enterocytes of the proximal segment are found to be concerned with lipid absorption. The absorbed fat gives rise to the presence of two forms of inclusions: lipid particles and lipid droplets. Enterocytes of the middle segment exhibit the typical ultrastructural features of pinocytosis; these consist of extensive invaginations of the luminal surface membrane and accumulation of vacuoles in the apical cytoplasm. Exogenous proteins are ingested by absorptive cells from the intestinal lumen by a process similar to that described in neonatal mammals. In the distal segment the absorptive cells have few, short microvilli.Besides the absorptive epithelial cells, goblet cells, endocrine cells, pearshaped cells, and plasma cells are occasionally found.