bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binding of concanavalin‐A to critical‐point‐dried and freeze‐dried human lymphocytes
Authors: Schneider Gary B. , Pockwinse Shirwin M. , Billings‐Gagliardi Susan 
Published: February 2005

AbstractWhen human lymphocytes are treated with concanavalin‐A (con A) and hemocyanin, the hemocyanin marker, which demonstrates con A binding sites, can be visualized by scanning (SEM) and transmission electron microscopy (TEM) on both critical‐point‐dried and freeze‐dried cells. The ability to visualize the hemocyanin marker by SEM, its quantity and distribution, were all similar in lymphocytes prepared by both drying procedures. By TEM, hemocyanin was seen adjacent to the plasma membrane on critical‐point‐dried lymphocytes. In contrast, freeze‐dried cells showed hemocyanin labeling at some distance from the plasma membrane (40–70 nm) as well as adjacent to it. The distribution of hemocyanin corresponded to the thickness of the amorphous coat seen on fixed, freeze‐dried cells. Therefore, the extracellular coat on freeze‐dried lymphocytes is a carbohydrate‐containing glycocalyx.
The regenerating liver: A site of erythropoiesis in the adult long‐evans rat
Authors: Naughton Brian A. , Kolks Gail A. , Arce Janet M. , Liu Philip , Gamba‐Vitalo Christina , Piliero Sam. J. , Gordon Albert S. 
Published: February 2005

AbstractErythropoiesis, which is primarily hepatic in the rat during fetal and early neonatal life, shifts almost entirely to the bone marrow in the neonatal‐adolescent stage of development. In the adult, extramedullary erythropoiesis has been demonstrated in the liver and spleen under certain pathological conditions when bone marrow red cell production is insufficient. In the present study, erythropoietic foci have been found in young‐adult rat liver regenerating 24–72 hr after subtotal hepatectomy. This erythropoiesis is both extravascular and sinusoidal, with some erythroblastic islands noted. The centrolobular hepatic area contains the highest concentration of erythroblasts. Peripheral blood reticulocytosis coincides with the appearance of these cells and this is considered as an indicator of effective erythropoiesis. Liver regenerating after partial hepatectomy produces significant quantities of erythropoietin (Ep) in response to hypoxia. Subtotal hepatectomy may confer upon the adult liver the ability to revert to a fetal‐like condition both in its ability to produce Ep and to function as a hematopoietic inductive microenvironment for erythropoiesis.
Increase in free cholesterol content of the adrenal cortex after stress: Radioautographic and biochemical study
Authors: Sharawy Mohamed , Dirksen Thomas , Chaffin Joe 
Published: February 2005

AbstractThe purpose of this investigation was to quantify free cholesterol biochemically and in radioautographs of 3H‐digitonin cholesterol complex in fasciculata cells of control and stressed rat adrenal cortex. Stress was induced by ether, laparotomy, and adrenal and intestinal handling. Control rats were anesthetized with nembutal. All animals were killed ten minutes from the beginning of anesthesia. The adrenals were excised and either fixed in glutaraldehyde containing 3H‐digitonin or homogenized for biochemical determination of free cholesterol. The plasma corticosterone level of each animal was measured. The fixed adrenals were processed, using different methods of dehydration and embedment, for light and electron microscopic radioautography. The mean number of silver grains (X̄) per unit area of zona fasciculata was counted from light microscopic radioautographs. Crystals of cholesterol‐digitonide complex were more numerous in stressed fasciculata cells, particularly over SER. Silver grains were localized over or close to the crystals. The X̄ for stressed rats was significantly higher than control values, indicating more free cholesterol in fasciculata cells of stressed rats. The results were not affected by either the method of dehydration or the type of embedding medium used. The morphologic results were substantiated by biochemical findings of increase in free cholesterol in adrenals of stressed rats. Plasma corticosterone was significantly high in stressed rats. The increase in free cholesterol in stimulated fasciculata cells is consistent with a previously reported increase in cholesterol esterase activity after ACTH stimulation.
Intracellular dynamics in pituitary mammotropes throughout the rat estrous cycle. II. Changes in synthetic and secretory organelles
Authors: Poole Max C. , Mahesh Virendra B. , Costoff Allen 
Published: February 2005

AbstractThe organellar dynamics within mammotropes (prolactin secreting cells) of the anterior pituitary were examined using morphometry throughout the four‐day rat estrous cycle. Two predominant periods of maximal organellar activity were found. The first period, which occurred during proestrus, resulted in two peaks of serum PRL at 6 pm and 12 m proestrus, while the second occurred during middiestrus‐2 and resulted in an increase of pituitary PRL, but not a major serum PRL peak. The mitochondrial volume rose prior to that of other organelles during early proestrus, rising 110% from 4 am late diestrus‐2 to 6 pm proestrus. However, the number of mitochondria per cell remained constant throughout the cycle. The volumes of rough endoplasmic reticulum (RER) and Golgi complex reached maximal proportions at 8 pm and 12 m proestrus, respectively. The RER volume was 153% greater than at 4 am late diestrus‐2, while the Golgi complex had increased by 200%. We suggest that changes in the RER and Golgi complex volumes were the result of two processes: the synthesis of new membrane and the swelling of existing complexes. This study further substantiated that the serum peak of PRL at 6 pm proestrus is the result of stored mature granules being released, whereas the PRL peak at 12 m proestrus is due to the immediate release of hormone without any storage.
Somitogenesis in cultured embryos of the Japanese quail, Coturnix coturnix japonica
Authors: Packard David S. 
Published: February 2005

AbstractThe ability of unsegmented paraxial mesoderm from Japanese quail embryos to form somites was studied by culturing pieces of embryos, containing the segmental plates, on an agar medium. In the first experiments, two explants were prepared from each donor embryo. Both explants contained a segmental plate and neural tube, but only one contained notochord. The explants containing notochord formed 11.4 ± 2.1 somites, while the explants without notochord formed 11.1 ± 1.3 somites. It was concluded that explants containing Japanese quail segmental plates readily form somites in culture and that the continued presence of the notochord is not required for these somites to form. In a second series of experiments, one explant from each donor embryo contained neural tube and notochord along with the segmental plate, while the corresponding explant did not contain axial structures. The results, which were similar to those obtained in the first experiments, indicated that neither neural tube nor notochord is required for somitogenesis in vitro. Additional experiments demonstrated that bilateral symmetry extends to the unsegmented somite mesoderm, where there was a strong tendency for each segmental plate of a given embryo to form the same number of somites. It was also shown that over a three‐fold range of segmental plate length, there was only a slight tendency for shorter segmental plates to make fewer somites. It was estimated that Japanese quail embryos having five to 21 pairs of somites have segmental plates that represent 11.3 ± 2.9 prospective somites each.
The development of the sinusoids of fetal rat liver: Morphology of endothelial cells, Kupffer cells, and the transmural migration of blood cells into the sinusoids
Authors: Bankston Patrick W. , Pino Richard M. 
Published: February 2005

AbstractThe fine structural development of rat fetal liver sinusoids from 10 to 22 days gestation was studied. Colloidal carbon (Pelikan ink) was injected into 14‐22 day gestation fetuses via the umbilical vein to assess the continuity of the sinusoidal lining and the phagocytic ability of the developing lining cells. Endothelial cells, devoid of an underlying basal lamina, form the bulk of the vascular lining at all gestational ages. These cells possess typical intercellular junctions and fenestrae with diaphragms before 17 days gestation. Transendothelial open fenestrations, typical of the adult liver, appear around 17 days gestation, increasing in number for the remainder of gestation. Although fenestrae possessing diaphragms are permeable to carbon before 16 days gestation, open fenestrations, first seen at 17 days gestation, allowed large amounts of carbon to reach the extravascular space. Endocytosis of carbon by endothelial cells was accomplished exclusively by large bristle‐coated vesicles. Endothelial cells were also seen to be involved in transmural diapedesis of newly formed erythrocytes and megakaryocyte processes from the extravascular space by forming a temporary migration pore allowing these cells and processes to enter the circulation. At the end of gestation, blood‐forming activity had nearly ceased, and only the space of Dissé separated the lining cells from the parenchymal cells. Kupffer cells were easily identified as early as 13 days gestation by their content of phagosomes and engulfed erythrocytes. The Kupffer cells are much more avid in the phagocytosis of carbon than are endothelial cells. Toward the end of gestation, some Kupffer cells develop a homogeneous “sticky coat” to carbon.
The stem‐cell zone of the small intestinal epithelium. IV. Effects of resecting 30% of the small intestine
Authors: Bjerknes Matthew , Cheng Hazel 
Published: February 2005

AbstractIn the mouse jejunum, as in the rat, a new steady state was established 3 weeks after resection of 30% of the small intestine. The mean height of a villus, crypt, and proliferative zone increased. We studied the effects of this new steady state on the distribution of the four main epithelial cell types and on the stem‐cell zone. Beginning 2 cm distal to the ligament of Treitz, 10 cm of jejunum were resected. In control animals the jejunum was transected 12 cm distal to the ligament of Treitz and then rejoined. The mice were killed 1 and 3 weeks after surgery and a piece of jejunum 4 cm distal to the anastomosis collected. One hour before death the animals were given an injection of 1 μCi/gm 3H‐thymidine. The tissue was embedded in Epon and then serial 1 μm sections were prepared and radioautographed. One week after resection there was a transient increase in the proportion of enteroendocrine cells in the crypts. This returned to control levels 3 weeks after resection. Thus, there appeared to be a feedback from the enteroendocrine population onto enteroendocrine cell production. After resection, amplification of mucous cell numbers by mucous cell division was reduced and yet normal proportions of mucous cells were observed in the epithelium. Therefore, an increased proportion of stem‐cell output must have been committed to the mucous and enteroendocrine cell lines. The increased height of the proliferative zone that followed 30% resection was not due to an increase in the number of transit divisions through the proliferative zone. Instead it was due to an increased output from the stem‐cell zone into the proliferative zone. Evidence was presented which indicates that the increased output from the stem‐cell zone was due to an increased number of stem cells in the zone, at the expense of non‐stem cells. The height of the stem‐cell zone, as indicated by the Paneth cell distribution, the mucous cell distribution, and the distribution of labeled mucous cells, did not change after 30% resection.
Distribution and structure of the adrenocortical homologue in the garpike
Authors: Bhattacharyya Tapan K. , Butler David G. , Youson John H. 
Published: February 2005

AbstractThe microanatomy of the yellow corpuscles (adrenocortical homologue, AH) in the holostean fish, Lepisosteus spp., was studied by serial sectioning, steroid histochemistry, and electron microscopy. The modification of this tissue to short‐term ACTH treatment was also observed. The distribution of the AH within the renal tissue of the garpike phylogenetically represents a more advanced condition than that seen in its closest holostean relative, the bowfin, and appears to approximate that in teleosts. The homology of this tissue to vertebrate adrenocortical tissue was established by the positive identification of the enzyme, Δ5‐3β‐hydroxysteroid dehydrogenase, and by the ultrastructural features of the cells before and after ACTH administration.The AH cells possess fine structural features characteristic of steroidogenic cells, namely, polymorphic mitochondria with tubular cristae, abundant tubules of smooth endoplasmic reticulum, a prominent Golgi complex, and lipid droplets. Other interesting features include the presence of annulate lamellae and a variety of dense bodies. Digitonin perfusion results in the deposition of presumed, cholesterol‐digitonide crystalline spicules on the surface microplicae of the cells and as dense accumulations in association with smooth endoplasmic reticulum. ACTH administration results in swelling of mitochondria, a loss of their cristae, and a decrease in electron density of their matrices. Alterations also occur in the smooth and rough endoplasmic reticulum, and large osmiophilic inclusions of irregular profile appear. Some of the ACTH‐induced modifications are similar to those observed in the adrenocortical cells of other vertebrate groups following comparable stimulation.
Tenotomy of the avian anterior latissimus dorsi muscle. I. Effect of age on fiber‐type transformation and regeneration from the stump in chicks
Authors: Hikida Robert S. , Wang Roomfang June 
Published: February 2005

AbstractThe chick's anterior latissimus dorsi muscle (ALD) was tenotomized at its origin at either 1 day or 4 weeks of age, and investigated histochemically and ultrastructurally at intervals thereafter to determine whether muscle fiber‐type transformation from a slow to a twitch type is greater in young birds than older birds. No transformation of fiber type occurred in either procedure, but a new muscular connection regenerated between the scar tissue at the end of the original tenotomized stump and the former origin. This regenerated muscle had a mosaic pattern of fiber types, as demonstrated by myofibrillar ATPase activity, and contained predominantly fast fibers, as contrasted with controls or the tenotomized portion, which contained predominantly slow tonic muscle fibers. The regenerated portion contained muscle spindles. The original portion of the tenotomized muscle was indistinguishable from the control muscle. These responses of the chick ALD to tenotomy are quite different from those in the pigeon, which are reported in the following study.
Freeze‐fracture study of rat ventral prostate: The columnar epithelial cell
Authors: Kachar Bechara , da Silva Pedro Pinto 
Published: February 2005

AbstractThe organization of the secretory epithelium of the rat ventral prostate as seen by freeze‐fracture is analyzed. Ultrastructural interpretation of the tall columnar epithelial cell is facilitated by the axial regionalization of the cytoplasm. The endoplasmic reticulum, which exists in all the regions of the cell, appears to have a role in the maintenance of cellular organization. Its cisternae delimit the spaces for the nucleus, the Golgi, and the apical secretory apparatus. Elements involved in the formation of secretory products for export are located within the apical region of the cell and are regionally separated from the Golgi complex. Structural and functional specializations of the plasma membrane in the apical, lateral, and basal areas are illustrated. Artifacts related to specimen preparation procedures are reported. Displacement of membrane particles, which we observed in the fracture faces of plasma and intracellular membranes, appears related to fixation at low temperature. Fixation at 37°C, which does not induce membrane‐particle displacement, results in proliferation of tight‐junctional elements.
Electron microscopy of the red pulp of the dog spleen including vascular arrangements, periarterial macrophage sheaths (Ellipsoids), and the contractile, innervated reticular meshwork
Authors: Blue Julia , Weiss Leon 
Published: February 2005

AbstractThe vascular and stromal arrangements of the red pulp in congested and contracted dog spleens were studied by transmission electron microscopy. Each dog had been injected intravenously with Thorotrast to label actively endocytizing cells. Only macrophages ingested Thorotrast. The proximal portion of each arterial capillary was surrounded by a “periarterial macrophage sheath” (PAMS), a term we introduce to replace the term “ellipsoid”. PAMS were composed of a fine meshwork of reticular cells and reticular fibers which held tightly‐packed macrophages and interspersed blood cells. These macrophages, as well as those in the reticular meshwork of red pulp, contained Thorotrast, cell debris, and deposits of hemosiderin. The arterial capillary at the center of each PAMS was formed by parallel, rod‐shaped endothelial cells and discontinuous layers of basement membrane and reticular‐cell cytoplasm. PAMS were tapered at their distal ends; the terminal portion of the arterial capillary continued beyond the PAMS to end in the reticular meshwork of red pulp. Endothelial cells in the terminal arterial capillaries were separated by gaps through which blood cells passed into the spaces of the reticular meshwork of red pulp. The reticular meshwork was formed by reticular cells which appeared to be specialized for contraction. These cells were filled with thin filaments and possessed plasmalemmal dense bodies as found in smooth muscle cells. Furthermore, the reticular meshwork was innervated by unmyelinated adrenergic axons which probably were derived from nerves that followed arterioles. Axons were enclosed in surface invaginations of cells which were similar to reticular cells in shape and cytologic detail and which we called “axon‐bearing reticular cells”. Axon‐bearing reticular cells were inserted between the branches of the reticular cells that formed the meshwork. Venous sinuses formed an anastomosing system of vessels draining into pulp veins which then joined trabecular veins. Sinuses were formed by parallel, rodshaped endothelial cells encircled by strands of basement membrane and reticular‐cell branches. Endothelial cells lay closely side by side except where inter‐endothelial slits were opened by blood cells passing into the lumen or by pseudopodia of macrophages which lay outside the sinus. Cell traffic across the sinus wall was greatest in areas where blood cells were mixed with plasma. Congested spleens stored concentrated red cells in both sinuses and the reticular meshwork; contracted spleens were emptied of blood. The reticular meshwork may contract to assist trabecular and capsular smooth muscle in expelling stored red cells and effecting hemoconcentration.
Myelopoiesis in lymph nodes of mice. Enhancement effect by the injection of trypan blue or india ink after birth
Authors: Sesma P. , Vázquez J. J. 
Published: February 2005

AbstractMyelopoiesis in lymph nodes was studied in newborn mice under normal conditions and after treatment with trypan blue and carbon particles. In the mouse lymph node, myelopoiesis normally takes place between the fourth and twelfth day after birth, then decreases while an intense proliferation of the lymphocytic population simultaneously takes place. Myelopoiesis manifests itself as clusters of cells, mainly of the neutrophilic line, located around post‐capillary venules (PCV's) in the medulla. The injection of trypan blue or carbon particles (India ink) causes an enhancement of myelopoiesis and a delay in the development of the lymphocytic population. Myelopoiesis includes not only granulopoiesis but also the formation of erythroid clusters and occasional megakaryocytes. Three possibilities should be considered to explain the enhancement of myelopoiesis: (1) blockade of the reticuloendothelial system caused by overloading with particulate matter; (2) induction of humoral myelopoiesis‐stimulating factors; and (3) stimulation of pluripotent stem cells through dye injection.
An immunocytochemical and routine electron microscopic study of LH and FSH cells in the human fetal pituitary (1)
Authors: Currie R. William , Faiman Charles , Thliveris James A. 
Published: February 2005

AbstractAnterior pituitaries from 17 human fetuses, 9.5 to 16.5 weeks in gestational age, were obtained to study the morphological development of gonadotropes as a function of age and sex.Routine electron microscopy alone was inadequate in determining which granulated cells produced the gonadotropins, owing to the similarities among granulated cells in the youngest fetuses as well as to the continuing differentiation of these cells. Therefore, electron‐microscopic immunocytochemistry was employed for identification of gonadotropes. LHβ and FSHβ antisera were used, and dilution and absorption tests were performed to determine the degree of cross‐reactivity with LHβ, LH, FSHβ, FSH, CGβ, and CGα. Both antisera completely cross‐reacted in parallel fashion with their respective β subunits, as well as with their respective intact hormones. Cross‐reactivity with the other absorbents was minimal, partial or nonexistent. With the LHβ antiserum, LHβ and intact LH appeared to be equipotent in absorption studies; whereas with the FSHβ antiserum, 10 times as much intact FSH was required to effect displacement as with FSHβ. These specificity studies, coupled with the failure of previous investigators (Kaplan et al., 1976a) to find free β subunits in the human fetal pituitary, suggest that staining of the granules was due to the presence of intact LH or FSH.Cells containing LH and FSH were identified immunocytochemically in the pituitaries of all the fetuses examined. Sex and age differences were qualitatively assessed. The number of cells and granules per cell stained with either LHβ or FSHβ antiserum, as well as the staining intensity with both antisera, increased as a function of fetal age. A sex difference was also evident, in that pituitaries of older females revealed more granules per cell and more cells stained with either LHβ or FSHβ antisera than those of males of comparable ages.These findings agree with the concept that the human male fetal pituitary produces less gonadotropin prior to mid‐gestation than the female gland, perhaps because of feedback inhibition by testicular testosterone secretion at this time.
Hormonal effects on the contractile apparatus of the myometrium
Authors: Kelly Robert E. , Verhage Harold G. 
Published: February 2005

AbstractThe effect of estradiol‐17β (E2) and progesterone (P) on the structure of myofilaments of the smooth muscle of the myometrium of cats was studied by electron microscopy. Animals which had been ovariectomized for at least four weeks were divided into three treatment groups. Group I received no additional treatment. Group II animals were treated for 14 days with E2, and Group III animals were treated for 14 days with E2 and then with E2 and P. The smooth muscle of the uterus of Group I animals displayed a single array of thin (< 10nm) filaments only. Group II animals displayed in all cases a double array of thick (14–16 nm) filaments, whereas Group III exhibited a single array of thin (6–8 nm) filaments only. These results suggest that E2 induces assembly of thick filaments in ovariectomized cats while P promotes thick filament disassembly. It is suggested that this alteration of the structure of the thick filament may be involved in the mechanism by which these hormones alter the contractile activity of the myometrium during estrus, pregnancy, and at parturition.