bluuebunny/crossref_metadata_2025_split huggingface dataset:
Migration and turnover of entero‐endocrine and caveolated cells in the epithelium of the descending colon, as shown by radioautography after continuous infusion of 3H‐thymidine into mice
Authors: Tsubouchi S. , Leblond C. P. 
Published: February 2005

AbstractAdult male mice were given a continuous infusion of about 0.5 μCi of 3H‐thymidine per gram body weight per day for periods varying from 1 to 60 days. Semithin sections of descending colon were cut from plastic‐embedded blocks and stained by a method combining silver impregnation and iron hematoxylin, by which argentaffin entero‐endocrine cells and caveolated cells could be identified. From radioautographs, the labeling index of these cells was determined.One to three days after the beginning of 3H‐thymidine infusion, label is observed in some of the stained entero‐endocrine cells in the bottom of the crypts; the apices of these cells reach the crypt lumen and are joined to neighboring cells by terminal bars (junctional complexes). After five to seven days, labeled entero‐endocrine cells are seen on the sides of the crypts, where their base stretches along the basement membrane and their apex has lost its terminal bar connections to neighboring cells. Finally, by 13 and 24 days, labeled cells are observed within the epithelium at the mucosal surface. The turnover time, which is taken to be equal to the mean time required for migration from site of origin to site of loss on the mucosal surface, has been estimated at 23.3 days. This is much longer than the 4.6 days required by the two main cell types of the epithelium — vacuolated‐columnar and mucous cells — to travel the same route. It is likely that, after entero‐endocrine cells lose their terminal bar attachment to other epithelial cells, they migrate independently and very slowly.Labeled caveolated cells are first seen in the crypt bottom one day after the beginning of 3H‐thymidine infusion. By three to five days, they are on the sides of the crypts; their base is stretched along the basement membrane, but their apex retains its attachment to neighboring cells by terminal bars. By seven days, labeled caveolated cells are on the mucosal surface. Their turnover time has been assessed at 8.2 days. This is, again, longer than for the two main types to which they are bound by terminal bars throughout migration. The discrepancy is explained by the caveolated cells arising deeper in the crypts than most vacuolated‐columnar and mucous cells.
Differences in regional capillary distribution and myocyte sizes in normal and hypertrophic rat hearts
Authors: Gerdes A. Martin , Callas Gerald , Kasten Frederick H. 
Published: February 2005

AbstractData are reported which show significant regional capillary differences in left ventricular endocardium and epicardium of normal rats and of rats with hyperthyroid‐induced cardiac hypertrophy. The epicardial region of control rats has 38% more capillaries than the endocardial region. Control endocardial myocytes are 62% larger in cross‐sectional area than epicardial myocytes. Hypertrophic hearts exhibit regional differences in capillary density similar to those in the normal hearts, but there is an overall reduction of 12 and 17.5% in capillary density in both regions. The average cross‐sectional area of myocytes increases 34.5% in the epicardium and 22.5% in the endocardium.
Developmental changes in the fine structure of rhesus monkey amnion
Authors: King Barry F. 
Published: February 2005

AbstractThe purpose of this study was to examine developmental changes in the amnion with regard to: (1) the fine structure of the epithelial cells, (2) the nature and permeability of the intercellular junctions, and (3) the structure of extracellular matrix components in the subepithelial compartment. Comparisons were made between amnion from 26‐72 and 146‐170 days of gestation. Early in gestation, epithelial cells were squamous and had few apical microvilli; late in gestation, cells were cuboidal with numerous microvilli and a well‐developed glycocalyx. Epithelial cells from early gestation had large glycogen stores, well‐developed Golgi apparatus, granular ER, and relatively few 10 nm cytoplasmic filaments. Later, cells were similar except for less glycogen, somewhat more lipid droplets, and numerous 10 nm cytoplasmic filaments. Lateral cell borders were complexly interdigitated at both ages and desmosomes were the predominant type of cell junction. Occasional tight junctions were observed early in gestation; no tight junctions were observed near term. After exposure to peroxidase in vitro, reaction product was present in the intercellular spaces, and the epithelial cells demonstrated very limited pinocytosis. Early in gestation, the basal cell surface was smooth, had no specialized junctions, and was underlain by a complete basal lamina (BL). Late in gestation, the basal surface was thrown into numerous folds, had hemidesmosome‐like junctions, and an incomplete BL. Early in gestation, the BL contained ruthenium red‐positive particles; later, these particles were absent. Early in gestation, the BL had a layer of interstitial collagen fibrils beneath it; late in gestation, a thick layer of 12 nm microfibrils was interposed between the BL and the interstitial collagen. The microfibrillar layer appeared at about 72 days of gestation, when it was apparently formed between the basal cell surface and the partially detached basal lamina.The results support the view that amniotic epithelial cells remain metabolically active throughout gestation and that the intercellular pathway is important in the movement of certain large molecules across the epithelium. The microfibrillar layer may provide structural strength for the amnion late in gestation.
Utilization of the chick chorioallantoic membrane for in vitro growth of the embryonic murine kidney
Authors: Preminger Glenn M. , Koch William E. , Fried Floyd A. , Mandell James 
Published: February 2005

AbstractPrevious experimental investigations of embryonic kidney development with in vitro organ‐culture techniques have been limited by the short duration of graft viability and lack of detailed anatomic development. In a modified application of the chick chorioallantoic‐membrane (CAM) grafting technique, we have transplanted 11‐day‐old undifferentiated embryonic murine kidney rudiments and studied their differentiation and early morphogenesis.Surviving grafts, maintained for 5–10 days on the CAM, demonstrated well‐developed convoluted secretory tubules and highly branched collecting ducts. Definitive glomeruli were also identified in these grafts by the presence of efferent tubules, visceral and parietal epithelium, capillary tuft, and Bowman's space. In vitro branching of the ureteric bud preceded formation of definitive tubules. Sections of the CAM grafts appeared histologically comparable to the 14–15‐day in vivo embryonic metanephros. Grafts of 10‐day‐old rudiments showed minimal kidney development; fewer grafts survived, fewer tubules were formed, and fewer glomeruli developed. Our results indicate that the CAM is an efficient site for in vitro murine kidney development with both vascularization of the explant and extensive maturation, including the appearance of primitive nephron units.
Trophoblastic and uterine luminal epithelial surfaces at the time of blastocyst adhesion in the rat
Authors: Enders Allen C. , Schlafke Sandra , Welsh Alerick O. 
Published: February 2005

AbstractFixed uteri from rats on the afternoon of day 6 of pregnancy were split to expose the implantation chambers, their enclosed blastocysts, and the imprints of the blastocysts on the adjacent epithelium of the chamber. Some ofthe implantation chambers were prepared for scanning electron microscopy; other chambers were treated with colloidal iron hydroxide, with cationized ferritin, or with the tannic acid method, and subsequently were prepared for transmission electron microscopy. In this manner, the disposition of the surfacecoat markers on the surface of the blastocyst, surface of the uterus within the chamber, and the surface of the uterus that had been apposed to a blastocyst were compared. Despite the pronounced morphological differences between the microvilli of the uterine luminal epithelium in the imprint and those in the rest of the chamber, the binding of the markers was remarkably similar. No evidence of removal of surface coat could be found in that area of the uterus in contact with the blastocyst. In addition, in two instances in the cationized ferritintreated material, and in another instance in tannic acid‐stained material, regions of the apparently adhering trophoblastic cell membranes and uterine cell membranes had abundant coat materials and, possibly, even secretory materials interposed. When blastocyst‐sized glass beads were introduced into uteri from animals made pseudopregnant or unilaterally pregnant, the beads failed to elicit a decidual response and made an imprint that did not resemble the imprint of a blastocyst in an implantation chamber. It was concluded that, at least in the initial stages of adhesion, the blastocyst does not bring about a physical removal of the demonstrable aspects of the surface coat of the uterus. It was concluded further, that glass beads are not a suitable object for mimicking a blastocyst in the rat uterus.
Stereological analysis of the guinea pig adrenal: Effects of dexamethasone and ACTH treatment with emphasis on the inner cortex
Authors: Black Virginia H. , Russo James J. 
Published: February 2005

AbstractThis paper describes the morphological responses of adult male guinea pig adrenals to dexamethasone (DEX) and adrenocorticotrophic hormone (ACTH), in both qualitative and quantitative terms. Most organelles and inclusions are affected, but their responses often vary in the different cell types examined: zona fasciculata externa and interna, and zona reticularis.Following DEX the volume of lipid droplets increases in cells of zona fasciculata externa but decreases in zona reticularis; smooth endoplasmic reticulum decreases in fasciculata externa but increases in reticularis. Following ACTH, exactly the opposite occurs. This strongly suggests differing functions for these subcellular entities in each cell type, particularly for the smooth reticulum, as well as for the cells themselves.The volume of the Golgi complex markedly decreases following DEX in all cells but increases only in zona fasciculata interna and zona reticularis following ACTH. These deeper cortical cells are known to secrete at least one sulfated steroid, dehydroepiandrosterone sulfate, and these changes in the Golgi complex strengthen the suggestion that the Golgi plays a role in sulfation of steroids.Mitochondrial volume and number decrease in all cells following DEX, supporting their role in steroidogenesis. Further decreases in their volume, accompanied by increases in their number following ACTH, may be related to a proliferation of mitochondria in response to ACTH.Changes in peroxisome volume and number, following DEX and ACTH, suggest a possible role for these organelles in steroid cell metabolism.Lysosomes decrease in volume in all cells following ACTH. This does not support the recently suggested concept that they play a role in steroid secretion.
Motor‐end‐plate and nerve distribution in a histochemically compartmentalized pennate muscle in the cat
Authors: Galvas Patrick E. , Gonyea William J. 
Published: February 2005

AbstractPrevious investigations in this laboratory have shown the flexor carpi radialis muscle (FCR) of the cat to be compartmentalized with regard to the distribution of muscle fiber types. This study was undertaken to determine whether each compartment of the FCR had a distinct motor innervation band, or whether there was only one innervation band, as has been reported previously for other muscles. In order to assess variation in motor innervation banding patterns, the innervation bands were correlated with the muscle‐tendon architecture. Each compartment of the FCR possessed a distinct innervation band. In addition, it was observed that the nerve to the FCR divided into a number of separate intramuscular branches which were distributed to the different histochemical compartments. It is possible that muscle fibers innervated by a single intramuscular nerve branch, and possessing a discrete innervation band, are locally organized within subdivisions of the FCR. It is hypothesized that the compartmental organization of the FCR would allow discrete regions of the muscle to function independently when performing different motor tasks.
“M” cell distribution in follicle‐associated epithelium of mouse peyer's patch
Authors: Smith M. W. , Peacock M. A. 
Published: February 2005

AbstractThe distribution of “M” cells within the follicle‐associated epithelium (FAE) of mouse Peyer's patches has been estimated from a series of SEM micrographs. “M” cells are found generally to be distributed evenly throughout the higher regions of the FAE. The frequency with which “M” cells occur decreases in the lower regions of the FAE. No “M” cells are found in the follicle‐associated crypts. “M” cell microvilli are longer than those of enterocytes found at the base of the follicle‐associated crypts and shorter than those found on enterocytes in other parts of the FAE.No lymphoid cells occur within the epithelium of the follicle‐associated crypt. Lymphoid cells in the higher regions of the FAE are associated closely with “M” cells. There is, in the lower regions of the FAE, a transitional zone where lymphoid cells occur both free within the epithelium and closely associated with “M” cells. It is suggested that an initial close association of lymphoid cells with young, fully differentiated enterocytes is responsible for the latter's subsequent transformation to “M” cells.
Comparative histochemical study of prosimian primate hindlimb muscles. II. Populations of fiber types
Authors: Sickles Dale W. , Pinkstaff Carlin A. 
Published: February 2005

AbstractThe populations of fiber types in hindlimb muscles of the tree shrew (Tupaia glis), lesser bushbaby (Galago senegalensis), and the slow loris (Nycticebus coucang) were described and an attempt was made to correlate populations of fiber types and locomotor patterns. Muscle fibers were assigned to one of the following groups: fast‐twitch glycolytic (FG), fast‐twitch oxidative‐glycolytic (FOG), and slow‐twitch oxidative (SO). Histochemical techniques for the demonstration of alkaline‐ and acid‐stable ATPases, succinic dehydrogenase, and mitochondrial á‐glycerophosphate dehydrogenase were used in the classification of muscle fibers. Results indicated that the FG fiber type is the predominant fiber type in muscles used for jumping, the FOG fiber type is predominant in muscles used for running, and the SO fiber type occurs in high percentages in postural muscles. The SO fiber was also the most common fiber in muscles of the slow loris‐‐a species that exhibits a slow, deliberate, sustained locomotor pattern. Intramuscular regional variations in populations were seen in some larger muscles of the tree shrew, but not in the lesser bushbaby and slow loris. Our results did not support the contentions of others that analogous muscles in different species have similar populations of fiber types.
An ultrastructural investigation of developing vasomotor innervation in rat peripheral vessels
Authors: Todd Mary E. , Tokito Mariko K. 
Published: February 2005

AbstractThe developing innervation was investigated in three muscular peripheral arteries from male Wistar rats. These were the superficial epigastric and saphenous arteries, branching from the femoral artery in the thigh, and the tail artery. At maturity the tail and saphenous are similar in size and the superficial epigastric is about half the size of the other two. They are approximately the same size at birth and were chosen because of the resemblance of the tunica media among them. The general pattern of the developing innervation was similar in all three, starting with nerve processes containing mainly empty vesicles. As development proceeded, the processes usually were enclosed within Schwann cells, and both the number of clear vesicles and the number of vesicles with dense cores increased. Tubular membranes probably budded off vesicles. The development of the innervation was mainly postnatal, although some processes seen in the fetus may have been growth cones. The tail artery was the latest to develop recognizable nerves, although the number increased dramatically and had surpassed those in the other two vessels by 12 days of age. It had the densest nerve plexus at maturity. Only adrenergic vasomotor innervation was present in these vessels. The nerves retained a precise relationship, adjacent to the outermost layer of smooth muscle cells and external elastic lamina, throughout development. The Schwann cell population increased very slowly and was similar in each vessel at each age. This meant that the tail artery had many more nerve processes per Schwann cell than the other two vessels. These three muscular arteries, then, varied in the rate of development of their adrenergic innervation and in the final density.
Some observations on sperm transport through the uterotubal junction of the rat
Authors: Gaddum‐Rosse Penelope 
Published: February 2005

AbstractEntry of spermatozoa into the oviducts of mammals is restricted by the uterotubal junctions. The extent to which these junctions act as selective valves, or filters, for sperm transport has not been determined. A new technique has been developed that permits the direct visualization of sperm transport through the uterotubal junction of the rat in vitro. After mating or artificial insemination, the female tract is removed to a special “observation dish” containing oxygenated Earle's solution maintained at 37°C. The oviducts are severed 1.0–1.5 mm above the uterotubal junctions. Under appropriate magnification and with oblique transillumination, spermatozoa may be observed emerging from the cut ends. It was noted that only motile spermatozoa emerged and that they usually appeared individually, with an interval of several minutes between each. Their egress was not directly related to contractions of the uterine cornu. Neither immotile spermatozoa nor a dye solution were observed to pass through the uterotubal junction. It is concluded that sperm motility is important, and probably essential, for sperm entry into the oviducts in the rat. Scanning electron microscopy revealed that the rat uterotubal junction forms a small mound or papilla projecting into the uterine cavity. No ciliated cells were observd in this region.
Effects of glucagon on hepatic glycogen and smooth endoplasmic reticulum
Authors: Striffler John S. , Cardell Emma Lou , Cardell Robert R. 
Published: February 2005

AbstractThe action of glucagon on hepatic glycogen and smooth endoplasmic reticulum (SER) was studied in samples of liver taken sequentially from anesthetized rats. The physiological state of each animal was assessed by continuously monitoring aortic blood pressure and blood lactate/pyruvate ratios. High hepatic glycogen levels were established by using 10–12 hr fasted control‐fed rats infused continuously with glucose. In rats receiving glucose only, hepatic glycogen levels remained above 5.0% during the 4‐hr period of glucose administration. Centrilobular hepatocytes displayed an abundance of glycogen which often appeared dispersed with elements of SER between the glycogen particles. Periportal cells had dense clumps of glycogen with few vesicles of SER restricted to the periphery of the glycogen masses. The addition of glucagon to the glucose infusate caused a marked stimulation of glycogenolysis. In these rats, the hepatic glycogen level (x̄±SE) was 6.71±.15% 1 hr after glucose and declined after initiation of glucagon infusion as follows: 5.86±.29% (15 min), 4.89±.26% (1 hr), 2.16±.40% (2 hr), and 1.66±.29% (3 hr). The fine structure of hepatocytes showed a dramatic response to the administration of glucagon. The glycogen regions of the cells were noticeably decreased in size and number of glycogen granules 3 hr after initiation of glucagon infusion, and SER was abundant in both periportal and centrilobular hepatocytes. The interpretation offered is that glucagon induces the formation of new SER membranes which participate in glycogen breakdown and/or glucose release from hepatocytes.
The epithelium of the excretory duct of the human submandibular gland: A transmission and scanning electron microscopic study
Authors: Testa‐Riva Francesca , Puxeddu Paolo , Riva Alessandro , Diaz Giacomo 
Published: February 2005

AbstractThe duct of the human submandibular gland (Wharton) is lined by a pseudostratified epithelium consisting of principal and basal cells. Scattered among them are a few goblet and ciliated cells.The principal cells are columnar in shape with many mitochondria, numerous dense bodies and a central nucleus with some indentations. Their apical cytoplasm shows a number of clear vesicles, some of which are reactive to silver and are extruded by exocytosis into the lumen. Other vesicles, which are unreactive, may represent the products of the absorption process. A mechanism of apocrine secretion is also observed in the principal cells.Thus, with regard to its functions, the duct of the human submandibular gland modifies the composition of saliva by adding a secretory component to it. This latter material is derived from the goblet cells but chiefly from merocrine (exocytosis) and apocrine secretion of principal cells.
Rapid alterations induced by insulin in hepatocyte ultrastructure and glycogen levels
Authors: Thompson Ed W. , Parks William C. , Drake Richard L. 
Published: February 2005

AbstractThe speed with which insulin alters hepatocyte ultrastructure and glycogen levels in insulin‐deficient rats has been studied. Insulin deficiency was induced with alloxan, followed by insulin treatment with regular and NPH insulin. Rats were killed at various times after the insulin injection, blood samples were obtained, plasma glucose levels were determined, and liver samples were prepared for electron microscopy and glycogen determinations. Plasma glucose levels in insulin‐deficient rats declined to normal values by 4 hours post insulin, returning to insulin‐deficient levels by 8 hours post insulin. Hepatic glycogen was considerably reduced in the insulin‐deficient rats. By 1 hour post insulin hepatic glycogen increased, reached maximal levels by 8 hours, then declined to insulin‐deficient levels by 36 hours. The ultrastructural appearance of both centrilobular and periportal hepatocytes from insulin‐deficient rats showed abundant vesicular smooth endoplasmic reticulum (SER), decreased rough endoplasmic reticulum (RER), and enlarged RER intracisternal spaces. One‐half hour post insulin, centrilobular hepatocytes were unchanged. In periportal hepatocytes, however, vesicular SER was no longer visible, the RER intracisternal spaces appeared normal, and the amount of RER had increased. By 1 hour post insulin the centrilobular hepatocytes showed similar ultrastructural changes. These changes became more pronounced in the next few hours and remained through 24 hours. By 36 hours both centrilobular and periportal hepatocytes appeared similar to those in the insulin‐deficient rat. These results demonstrate the rapid and lobular‐specific effects insulin has on the hepatocyte.