bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dependence of Sertoli cell maturation on the pituitary gland in the mouse
Authors: Bressler Robert S. 
Published: February 2005

AbstractPostnatal development of the Sertoli cell population was studied in testes taken from newborn mice and implanted into the testes of normal, hypophysectomized and testosterone‐treated hypophysectomized adult mice for 13, 15–17 and 17–19 days, respectively. Maturation of the Sertoli cell complement of each specimen was judged by two criteria: (1) the proportion of Sertoli cells exhibiting a nucleolonema; (2) the prevalence of specialized inter‐Sertoli cell junctions. In these respects implants recovered from normal hosts did not differ from sibling controls of the same age. Sertoli cells in implants recovered from hypophysectomized hosts retained the features observed in newborn controls, indicating that maturation of the Sertoli cells is dependent on normal pituitary function. Implants recovered from testosterone‐treated hypophysectomized hosts exhibited a degree of Sertoli cell development intermediate between those recovered from the other two host categories.
3H‐fucose incorporation into glycoproteins of toad bladder epithelial cells
Authors: Strum Judy M. , Ekblad E. B. Margareta 
Published: February 2005

AbstractElectron microscope autoradiography was used to detect the incorporation of 3H‐fucose into glycoproteins of toad bladder epithelial cells. After short exposure to 3H‐fucose, without a chase period, the Golgi regions of all four cell types were labeled. When exposure to 3H‐fucose was followed by chase periods (1, 3, 4 and 6 hours) the apical and basal‐lateral plasma membranes of granular cells were heavily labeled. Apical granules and the cytoplasm of granular cells were also labeled, suggesting that they both provide the means for glycoprotein transfer from the Golgi to the plasma membranes. The heaviest labeling in mitochondria‐rich cells, after the 1‐ and 3‐hour chase periods, was over the apical tubules, although the apical and basal‐lateral plasma membranes were also heavily labeled. After the 4‐ and 6‐hour chases, the labeling of the apical tubules decreased, whereas the labeling of the plasma membranes increased, strongly suggesting that in these cells apical tubules play a major role in the transfer of glycoproteins from Golgi to the plasma membrane. Our results demonstrate that the route of 3H‐fucose incorporation into plasma membrane glycoproteins and the rate of glycoprotein synthesis and breakdown are not the same in the two major epithelial cell types in toad bladder.
An immunocytochemical study of human pituitary mammotropes from fetal life to old age
Authors: Baker Burton L. , Yu Ya‐Yen 
Published: February 2005

AbstractThe objectives were to (a) describe the cytology and distribution of mammotropes in the human pituitary gland, (b) determine whether the mammotrope is a distinctive secretory cell type and (c) ascertain when it first appears in the fetal hypophysis. Identification of mammotropes was based primarily on the Sternberger peroxidase‐antiperoxidase immunocytochemical method used with an antiserum to human prolactin. Hypophyses from 25 male and 6 female adults, and 21 fetuses ranging in gestational age from 6 to 23 weeks were studied.In the adult two morphological forms of mammotropes were observed. Mammotrope I possessed a small perikaryon that commonly was located centrally in parenchymal cell cords. From the perikaryon long cytoplasmic processes extended toward neighboring capillaries. Mammotrope I reached its highest incidence in the posterolateral zones of the pars distalis. Mammotrope II possessed a larger perikaryon with short processes; cells of this form were fewer and occurred chiefly in the anteromedian zone. Mammotropes with intermediate morphological features that prevented classification into categories I or II were common in some hypophyses.Both forms of mammotropes were present prepuberally (one 6‐week and one 9‐year‐old male) and in adult males and females. Mammotropes were only slightly more prominent in females than males. Regression of mammotropes was evident in old age. Mammotropes were distinctly different from somatotropes, corticotropes, gonadotropes and thyrotropes. In the fetal hypophysis mammotropes appeared first at 14 weeks of gestational age and remained few through 16.5 weeks. Their number increased greatly at 23 weeks.
Morphological aspects of type II alveolar pneumocytes following treatment with puromycin in vivo
Authors: Collet A. J. , Chevalier G. 
Published: February 2005

AbstractUltrastructural modifications of type II pneumocytes (PNM‐II) in mice were analysed 125 and 155 minutes after puromycin treatment (12 mg/100 gm at 0, 30, 60 and 90 minutes). A quantitative evaluation of the cell compartments was carried out and the inhibition of protein synthesis in PNM‐II was monitored by light microscopic radioautography, following 3H‐leucine injection.In electron micrographs, following a 125‐minute puromycin treatment, the number and size of lamellar bodies, the precursors of lung surfactant material, appeared markedly reduced. The multivesicular bodies (MVB), which are normally very frequent in PNM‐II, had almost completely disappeared, as had composite bodies. Golgi saccules were dilated, while the area occupied by Golgi vesicles was enlarged. Observations following the 155‐minute puromycin treatment showed a strong enhancement of these modifications. Smooth and coated vesicles of the Golgi area, as well as peroxisomes, did not appear modified by puromycin. Elongated zones of autophagy were more prevalent after 125‐minute treatment than after the 155‐minute one.Small bodies were frequently observed in the cytoplasm, near the Golgi zone. They were bounded by a smooth membrane and contained tiny vesicles and/or electron‐dense lamellae similar to those present within the lamellar bodies. Parallel membranes formed folds, some of them in continuity with lamellar bodies, thus encircling portions of cytoplasm. These structures, which were few in number in controls, were very frequently observed in treated cells, mainly after the 125‐minute treatment.These extensive alterations of PNM‐II morphology appeared to be related to a disturbed production of pulmonary surfactant.
Spatial distribution of DNA‐synthesizing cells in colonic crypts of the guinea pig
Authors: Sawicki Wojciech , Blaton Olena , Pindor Maciej 
Published: February 2005

AbstractThe ascending colon of a guinea pig injected with tritiated thymidine was cut serially, autoradiographed and stained with periodic‐acid‐Schiff‐hematoxylin. Maps of transversely sectioned crypts were prepared with the use of a microscope eye‐piece projector. The number and angular positions of pulselabelled (DNA‐synthesizing) cells around the circumference of transverse sections of the crypt were recorded. A method of “statistics of the circumference” was applied in order to find the variances of angular distances between labelled cells and thereby to find the type of arrangement of DNA‐synthesizinbg cells in the crypt.The spatial distribution of DNA‐synthesizing cells, both around the crypt circumference and along the crypt, was found to be non‐random. While the pattern of nonrandomness around the crypt circumference is such that the DNA‐synthesizing cells tend to occupy positions in the crypt circumference at maximal distances from each other, DNA‐synthesizing cells along the crypt tend to occupy positions at minimal distances from each other. DNA‐synthesizing cells are arranged in the crypt in rows, each consisting of several cells and each parallel to the long axis of the crypt. Apparently the dividing cell of the crypt produces either two proliferating or two differentiating cells. No evidence of differential mitosis could be found.
Fine structure of secretory ameloblasts in the kitten
Authors: Kallenbach Ernst 
Published: February 2005

AbstractSecretory ameloblasts in lower second molars of 1‐week‐old kittens were studied with the elctron microscope after perfusion‐fixation with and without decalcification.Ameloblast height varied from 40–65 μm. Tomes' process presented a stepped profile with two type‐1 faces (presumably enamel secreting) and one type‐2 face (thought to be non‐secreting). The type‐1 face was associated with extensive membrane infoldings. The enamel facing the type‐1 face was lined by a dense border, and stippled material was present between cell membrane and enamel. The type‐2 face was characterized by minute membrane invaginations and, sometimes, stippled material between enamel and cell membrane. In cross section, the distal part of Tomes' process showed bilateral symmetry, with one dorsal, one ventral and two lateral aspects. It was suggested that enamel formation occurs in three stages. First, interrod enamel on the lateral aspects of Tomes' processes is formed by two adjacent amelblasts. Next, the interrod enamel on the dorso‐ventral aspects of Tomes' processes is formed mainly by the dorsal extension of one Tomes' process. Finally, the enamel rod is formed by one ameloblast.Stippled material was consistently present in the extracellular spaces between Tomes' processes and in irregularly shaped vesicles in the ameloblast apex, and occasionally in large masses between the ameloblast cell bodies. Spherical vesicles within the ameloblast, thought to be lysosomes, also could contain material resembling stippled material. The possibility was considered that stippled material is partly derived from enamel, and finally phagocytosed by ameloblasts. There was no clear morphologic evidence for merocrine secretion playing a role in the formation of either enamel, stippled material or the rod sheath.
The transmural migration and release of blood cells in acute myelogenous leukemia
Authors: De Bruyn Peter P. H. , Becker Robert P. , Michelson Sonia 
Published: February 2005

AbstractThe transmural passage of malignant blood cells from the extravascular parenchyma into the sinusoidal lumen has been studied in the bone marrow of rats with myelogenous leukemia. The Shay myelogenous leukemia was chosen as a model system because an increased bone marrow cellularity is, in this leukemia, usually accompanied by an increase in circulating myeloid cells. By means of light microscopy, transmission electron microscopy (TEM) and scanning electron micrroscopy (SEM) it was found that the sinusoidal endothelial lining of the bone marrow remains intact and continuous even in advanced stages of the disease. SEM shows that the malignant myeloblast‐like cell enters the sinusoidal lumen by means of a temporary migration pore, which appears only during the transmural passage of the cell.Certain nondegenerative changes in the sinusoidal blood vessels are associated with the myelogenous leukemia. The normal radial alignment of sinusoids about the central sinusoid is changed into a tortuous pattern, and intraluminal cytoplasmic bridges which impede the blood flow are formed by the endothelial cells.
Catecholamine accumulation in neural crest cells and the primary sympathetic chain
Authors: Allan I. J. , Newgreen D. F. 
Published: February 2005

AbstractCatecholamine accumulation in chick embryos of stages 16 to 24 was investigated using formaldehyde‐induced fluorescence. Fluorescence first appeared at stage 21 in the anterior sympathetic chain. After L‐DOPA treatment, this fluorescence appeared at stage 18. Noradrenaline could not advance the onset of fluorescence or reconstitute fluorescence after its depletion by reserpine at stages 22 to 24. Under no conditions could fluorescence be identified in neural crest cells prior to their aggregation to form the primary sympathetic chain. Noradrenaline induced fluorescence in the neural tube, notochord, myotome, sclerotome, gut mesenchyme and suprarenal cortical cells. In addition to these structures, the dorsal pancreas and some blood cells were fluorescent after 1‐DOPA treatment.The implication of the results for the neural crest origin of APUD (Amine Precursor Uptake Decaboxylase) cells is considered.
High‐voltage electron microscopy of extracellular fibrillogenesis
Authors: Frederickson Richard G. , Morse Dennis E. , Low Frank N. 
Published: February 2005

AbstractHigh‐voltage electron microscopy was employed to observe developing extracellular connective tissue elements in the cervical perinotochordal and perivertebral regions in the chick embryo from 2 through 15 days' incubation. During days 2 and 3, small (10 nm) and large (18–20 nm) microfibrils surrounded the notochord, becoming evident around fibroblast‐like cells in day 4. Amorphous material, globular granules and microfibrillar bundles were present at this time. Microfibrillar length increased as did the total population of microfibrils. At four days microfibrils 3–5 nm in diameter arose in all directions from globular granules. During day 9 and thereafter to day 15, microfibrillar diameters increased. This growth formed unit collagenous fibrils 30 nm in diameter or greater. Axial periodicity became evident at day 14.Small microfibrils appear to be composed largely of glycoproteins and do not contain a significant amount of collagen. The globular granules and associated filaments are probably proteoglycans. The amorphous material is believed to provide molecular collagen to developing fibrils. Large microfibrils and unit collagenous fibrils contain significant amounts of molecular collagen.
Electron microscopic immunohistochemical localization of α‐MSH in the rat brain
Authors: Pelletier Georges , Dube Donald 
Published: February 2005

AbstractUsing an immunohistochemical technique at the electron microscopic level, it has been shown that α‐MSH is localized within the small vesicles of a few cell bodies found in the arcuate nucleus and numerous nerve fibers widely distributed throughout the brain. These findings suggest that α‐MSH could possibly be considered as a neurotransmitter.
Effects of a tumor‐promoting agent on chondrogenesis
Authors: Pacifici M. , Holtzer H. 
Published: February 2005

AbstractChondroblasts exposed to the phorbol ester, PMA, rapidly lose their polygonal morphology, and rapidly cease to synthesize or accumulate the chondroblast‐specific Type IV sulfated proteoglycan. This striking effect is reversible if the cells are kept in PMA for up to 72 hours.A longer exposure induces irreversible effects and results in a population of cells, the vast majority of which lack the phenotypic properties of terminal chondroblasts.
The morphogenetic relationship of the temporal muscle to the coronoid process in human embryos and fetuses
Authors: Spyropoulos Meropi N. 
Published: February 2005

AbstractThe purpose of this investigation was: (a) to study the developmental relationships of the temporal muscle and the coronoid process during the critical initial stages of morphogenesis and (b) to correlate the developmental stages of the muscle and the bone with data describing the functioning of the muscles of mastication in utero.The heads of 41 human embryos and fetuses, 6 to 11 weeks, estimated fertilization age, were sectioned and examined under light microscopy. The findings are described in terms of six successive stages, each characterized by a major developmental change occurring during that stage.The data indicate that the temporal and masseter muscle anlagen begin to develop prior to the skeleton to which they ultimately become attached. The coronoid process differentiates subsequently as a discrete entity within the mass of the temporal muscle anlage at an estimated fertilization age of 7 to 7.5 weeks (23–24 mm CRL). At approximately eight weeks of age, the coronoid process unites with the main portion of the mandibular ramus. The findings here presented do not support the conclusion that the coronoid process is self‐differentiating as Washburn (′47) contended. Instead, the development of this feature of the human mandible represents a response that follows the differentiation of the temporal muscle. This conclusion is consistent with the observations drawn from a number of investigations concerning structural and functional development of the face.
Fusion of nasal swellings in the mouse embryo: Surface coat and initial contact
Authors: Gaare John D. , Langman Jan 
Published: February 2005

AbstractThe nasal region of 12‐day‐old mouse embryos was examined with the electron microscope to determine whether a surface coat and membrane specializations are involved in epithelial fusion between the medial and lateral nasal swellings. Ruthenium red was used to examine the distribution of the surface coat.Prior to contact, a surface coat is always present over the epithelial linings of the nasal swellings in the region of presumptive fusion, and it is often heavier in the fusing than in the non‐fusing regions. At the point of initial contact, the coat is present as a thin film between touching superficial cells, suggesting that it may mediate epithelial contact.The initial contact between the cells of the medial and lateral nasal swellings is made by short projections from one superficial cell to the surface of an opposing superficial cell. These points of contact then broaden into larger areas until the entire free membranes of opposing superficial cells meet. The contacting membranes, which are separated by a distance of approximately 6–10 nm and show an increased electron‐density, probably provide a firm adhesion between the nasal swellings.
Morphology and hormonal responsiveness of renal cortical tubules in vitro
Authors: Biddulph David M. , Wrenn Robert W. 
Published: February 2005

AbstractIsolated renal cortical tubules from male hamsters were prepared for studies in vitro in which the effects of parathyroid hormone (PTH) on cyclic nucleotide metabolism and efflux of intracellular calcium were investigated. Morphological studies were also conducted to evaluate the effects of the isolation procedure on the structural characteristics of the in‐vitro preparation of tubules. Tubules, consisting of proximal, distal and collecting duct segments, were observed by electron microscopy to retain specific cellular membrane specializations which characterize these segments in situ (microvilli; basal infoldings and junctional complexes). Organelles were generally normal in their appearance; however, some swelling of mitochondria and endoplasmic reticulum were occasionally observed. Enzyme activity, associated with either luminal membranes (alkaline phosphatase) or lysosome‐like organelles (acid phosphatase) was also retained following the isolation procedure. Preservation of the PTH‐dependent, adenylate cyclase system in isolated tubules was demonstrated, indicating that membrane receptors for PTH were intact. Effects of PTH on cyclic GMP concentrations as well as efflux of 45Ca were also demonstrated. These results indicate that the use of isolated renal tubules in vitro offers an excellent model system for further investigations concerned with mechanisms of hormonal action and regulation of cyclic nucleotide metabolism. The results also suggest a relationship in renal cortical tubules between PTH‐mediated production of cyclic AMP, metabolism of cyclic GMP and transport of calcium.
The corpus luteum of the guinea pig. Fine structure at the time of maximum progesterone secretion and during regression
Authors: Paavola Laurie G. 
Published: February 2005

AbstractThis report describes the fine structure of guinea pig luteal cells during the period of maximum progesterone secretion and throughout involution, in ovaries that have been fixed by perfusion, a technique that provides optimal preservation of steroid‐secreting tissues. Smooth endoplasmic reticulum (smooth ER), a prominent organelle in these cells, is particularly well preserved by this method of fixation. During the time of maximal progesterone secretion, luteal cells contain abundant tubules and cisternae of smooth ER, many mitochondria, a well‐developed Golgi complex and some lipid droplets. This fine structural picture is consistent with active steroidogenesis.Autophagy plays an important role in the regression of luteal cells in the corpus luteum. The onset of luteolysis is marked by the appearance of structurally complex autophagic vacuoles, one of which has not been described previously in luteal cells. This autophagic vacuole seems to originate from GERL (Golgi‐endoplasmic reticulum‐lysosomes) as a cup‐shaped structure, which subsequently increases in size and complexity. Regressing luteal cells also contain increased numbers of both dense bodies (lysosomes) and lipid droplets, and exhibit changes in nuclear and mitochondrial morphology. In contrast to previous reports in the literature, changes in the morphology of smooth ER were not observed as a characteristic feature of involution in corpora lutea of guinea pigs in the present study. Advanced regression of luteal cells is characterized by multiple fusion of lipid droplets and a decrease in the amount of smooth ER.Another mechanism active in the breakdown of the corpus luteum is the phagocytosis of luteal cells by macrophages. Although present at all stages, macrophages are most abundant in older corpora lutea, where they often surround dead or dying luteal cells.
Evidence of a specific nidation site in ruminants
Authors: Lee Sue Y. , Mossman Harland W. , Mossman Archie S. , Pino Guido Del 
Published: February 2005

AbstractThe site of umbilical cord attachment in ruminants indicates the limited segment of the uterus where blastocyst attachment occurs and could have potential significance for locating presumptive nidation sites. Measurements of the site of cord attachment were made on impala (Aepyceros melampus) and common duiker (Sylvicapra grimmia) at several stages of gestation. Both implant only in the right uterine horn although they ovulate from either ovary. Relative to uterine length, cord attachment in impala is somewhat closer to the cervix than it is in common duiker. As pregnancy advances in common duiker, the relative position of cord attachment becomes closer to the tubal end. This relationship was not seen in impala and may perhaps be attributed to inadequate data. Upon extrapolation of the data from common duiker, a presumptive attachment area is suggested for this species. This region is located at about 41% of the distance from the internal cervical os to the uterotubal junction. Similar cord attachment data could be used in any ruminant species to indicate the existence and location of a specific nidation site.
The fine structure of the melanocytes of the adult mouse hair follicle during their amelanotic phase (telogen and early anagen)
Authors: Silver Alene F. , Fleischmann Robert D. , Chase Herman B. 
Published: February 2005

AbstractMelanocyte‐precursor cells have been described previously in telogen and early anagen hair germs by observation of Epon sections using light microscopy. The existence of these precursor cells has not been generally accepted due to lack of ultrastructural evidence. It is our purpose to describe these cells using transmission electron microscopy. We studied hair germs of the dorsal skin of adult mice in the appropriate stages of the hair cycle prior to melanogenesis.Telogen melanocytes are distinguishable from adjacent keratocytes by their lack of desmosomes, lack of coarse clumps of microfilaments, sparsity of ribosomes, unusually few nuclear pores and presence of dendrites. Melanocytes in early anagen show extensive growth with abundant polysomes, elaborate RER and Golgi zones. They still differ from keratocytes in their lack of desmosomes and clumps of microfilament, and also in the occasional presence of premelanosomes.