bluuebunny/crossref_metadata_2025_split huggingface dataset:
The development and structure of the choledocho‐duodenal junction in Balaenopteran whales
Authors: Boyden Edward A. 
Published: February 2005

AbstractThree specimens from Balaenopteran whales have been available for study: a 20 mm embryo, a fetus 57 inches long and the ampulla duodeni of a 47‐foot adult. By reconstruction, dissections and histological preparations, it has been possible to show that the extrahepatic portion of the bile duct is really an elongated hepato‐pancreatic duct receiving ductules draining both rostral and caudal pancreatic lobes. After coursing through the pancreas, this duct pierces the intestinal muscle at the beginning of the pars descendens duodeni, then runs through the whole length of the longitudinal fold before emptying at the bottom of the pars descendens. In the adult, maceration methods have demonstrated that there is no vestige at all of a sphincter of Oddi. Presumably, this is a consequence of the absence of the gall bladder. Contrary to statements in the literature, a complete foramen epiploicum, vestibule and lesser peritoneal sac could be demonstrated as well as a long infracardiac bursa. Most interesting is the presence of a sizable valve in the portal vein at the point where it enters the liver.
Comparative observations of the eminentia cruciata in birds and mammals
Authors: Igarashi Makato , Yoshinobu Toshiko 
Published: February 2005

AbstractThe eminentia cruciata in vertical semicircular canals was observed in all birds and the turtle investigated. Minimal structural difference was observed among all birds utilized for their different flying activities. This eminentia cruciata was found even in a flightless penguin. A rudiment was found in the rat, cat, and dog, but not found in the guinea pig, flying squirrel, squirrel monkey, owl monkey, macaca monkey, or human.The dividing and frictional effects from this structure against the endolymphatic flow are expected in these vertical semicircular canals. The ampulla of the vertical semicircular canal contains one complete crista with planum semilunatum on each side, due to the presence of the eminentia cruciata.The phylogenetic significance is important; the existence of the eminentia cruciata is parallel to that of the sensura neglecta, and it is antagonistic to the development of the horizontal semicircular canal.
An engineering analysis of myocardial fiber orientation in pig's left ventricle in systole
Authors: Streeter Daniel D. , Bassett David L. 
Published: February 2005

AbstractThe concept of discrete layers and bundles of muscle as a basic structural arrangement in left ventricular myocardium was tested by measuring the helix angles at 1 mm intervals from endocardium to epicardium, using pig's heart in the contracted state. A fixed coordinate system was established which permitted measurement of corresponding sites in hearts of different dimensions.The helix angle was found to change from somewhat less than 90° endocardially to about −90° epicardially in an almost linear clockwise sequence, like a Japanese fan opened up. Approximately the same pattern was observed in the interventricular septum and the anterior, left and posterior walls. Generally, there was no abrupt change between the helix angle of papillary fibers and that of adjacent wall myocardium. Where occasionally abrupt changes in fiber orientation were demonstrated, no intervening septum could be discerned. The deviant fibers seemed to co‐exist as part of the same gross structure.The concept of a continuum more appropriately describes the basic structure of left ventricular myocardium. Lev and Simkins ('56) and Grant ('65) showed that there was no evidence of identifiable layers as defined by the presence of connective tissue septa. This study shows no evidence of identifiable layers as defined by (1) an abrupt change in fiber direction demarking the boundary of a layer and (2) a parallel fiber direction between such boundaries.
Fluorescent localization of catecholamine stores in the rat lung
Authors: Zussman William V. 
Published: February 2005

AbstractTo localize the stores of catecholamines present, normal rat lungs were examined with a histochemical fluorescence technique. Comparison was made with sections from animals infused with methylene blue to demonstrate the autonomic innervation usually observed. An extensive network of fine fluorescent fibers was seen in the mucosa of the entire bronchial tree. Coarse interstitial fibers adjacent to bronchi represented the largest monoamine stores observed, and communicated by delicate fibers with both the musculature and mucosa. Arterial fluorescence was less prominent, and a continuous subendothelial layer of coarse fluorescent material communicated with finer fibers in the muscular walls. The extensive fluorescent fibrous network visualized with the present method, demonstrating fine details of innervation, suggested an intimate relation between the bronchi and pulmonary arteries.
The effects of contraction and stretch of a muscle on morphology of its spindles
Authors: Bridgman Charles , Sweeney Susan , Eldred Earl 
Published: February 2005

AbstractThe effects of acute stretch, laterally applied pressure, and exterfusal contraction upon the morphology of spindles in cat muscles have been studied by making measurements from serial histological sections. Cross‐sectional areas of bag and chain intrafusal fibers were taken and the circumferences of spindle capsules measured at the equatoriallevel. From these area values the relative effects on length of the measured structures were inferred. 1. Stretch was found to lengthen the capsules and both bag and chain fibers. 2. Contracture induced by use of the drug ryanodine was accompanied by shortening of both bag and chain fibers. 3. Stretch was still effective in the presence of full contracture. 4. Pressure applied to the lateral surface of the muscle affectedboth bag and chain fibers.These findings taken with other considerations demonstrate the anatomical basis for the mechanism that is commonly assumed to cause the acceleration in discharge from primary and secondary endings with stretch and the “pause” with contraction of the gross muscle. The relation to a possible pressure sensing mechanism for secondary endings is discussed.
Synaptic contacts at nodes of ranvier in central nervous tissue
Authors: Khattab Fahmy I. 
Published: February 2005

AbstractParietal cortex, hippocampus and reticular formation of the medulla of normal rabbits were primarily fixed by glutaraldehyde perfusion followed by phosphate buffered osmium tetroxide. In electron micrographs of this material the central nodes of Ranvier exhibitedmost of the features of peripheral nodes. Branching was observed at central nodes which resembled branching of the myelinated axons at peripheral nodes. Two types of synapses were observed at the node. In the first type the axon formed a process which ended in a bouton, synapsing with a dendritic spine, while in the other type the axon bulged at the node to form the bouton.
A light and electron microscopic study of Kurloff bodies in the blood and spleen of the guinea pig
Authors: Berendsen Peter B. , Telford Ira R. 
Published: February 2005

AbstractThe Kurloff body of guinea pig mononuclear leukocytes was studied by light and electron microscopy of blood and spleen. Electron microscopy disclosed the presence of extensively dilatedendoplasmic reticulum, clusters of small vesicles, and clumps of long parallel fibers in the cytoplasm. The osmiophilic inclusions contained many myelin figures, both around the periphery and free in the matrix. Evidence for motility of these cells was noted.Rods, filaments, and spheres seen in supravital preparations appear as myelin figures when seen with the electron microscope. Although historically considered, parasitism, nuclear extrusion and phagocytosis of cells are unlikely as causal in the formation of the inclusion. Being based on contradictable evidence, a lysosomal origin is doubted. The formative process isfelt to be either one of intracellular secretion or of a sequestering and concentration of a serum molecular component.
The relationship between the histological localization of alkaline phosphatase activity and appearance of lymphocytes in lymphocytic tissue of the embryonic and neonatal rabbit
Authors: Hostetler Jeptha R. , Ackerman G. Adolph 
Published: February 2005

AbstractVarious lymphocytic organs (thymus, spleen, appendix and lymph node) were removed from embryonic and neonatal rabbits between the eighteenth day of gestation and the tenth postnatal day. These tissues were studied morphologically and histochemically using a variety of procedures in order to determine the manner of lymphocyte formation in relation to the pattern of histochemical differentiation in these lymphocytic tissues. Of particular interest was the consistent development of alkaline phosphatase activity in non‐thymic lymphocytic organs one to two days prior to the appearance of lymphocytes in these tissues. The regional development of alkaline phosphatase activity in these non‐thymic lymphocytic organs corresponded with the sites of appearance of the first lymphocytes in these organs and with the regions of subsequent lymphocytic proliferation during the developmental stages of the spleen, lymph nodes and appendix of the rabbit.Specifically, alkaline phosphatase activity localized in the mesenchymal cells surrounding the developing arteries of the spleen, in the developing cortical region of the lymph nodes and in the lamina propria of the domed elevations of the appendix. In contrast, neither the thymus nor the surrounding connective tissue of the thymus exhibited demonstrable alkaline phosphatase activity during the early development of the thymus into a lymphocytic organ. Significantly, the first cells of the lymphocytic series to develop in the spleen, lymph nodes and appendix in the embryonic rabbit were of small or medium size in contrast with the thymus where lymphoblasts were the first recognizable cells of the lymphocytic series.These observations suggest that alkaline phosphatase is intimately associated with the development of lymphocytes in potential non‐thymic lymphocytic organs. The mechanisms of alkaline phosphatase action, although not clear, may act to induce the in situ transformation of lymphocytes, provide a suitable environment for lymphopoiesis or serve as a chemotactic agent, attracting blood‐borne lymphocytes to these regions.
Plasma membrane changes during keratinization
Authors: Farbman Albert I. 
Published: February 2005

AbstractNumerous electron microscopic studies have demonstrated that the plasma membranes of keratinizing epithelial cells undergo striking morphological changes. From a more or less symmetrical, trilaminar structure similar to that described for most cells, the membrane undergoes a marked increase in thickness and becomes highly resistant and impervious to the action of strong reagents. In the present electron microscopic study on rat tongue epithelium, this membrane thicken‐ing was observed to begin by the appearance within cells of a moderately dense band of material, about 100 A thick, in the peripheral cytoplasm against the intracyto‐plasmic face of the plasma membrane. This peripheral dense band was observed in epithelial cells each of which still possessed a nucleus and all its usual cytoplasmic organelles. Following its initial appearance, this peripheral intracytoplasmic band increased in density so that it became indistinguishable from the inner layer of the plasma membrane. The electron microscopic image at this stage gave the impression that the inner layer of the plasma membrane had undergone a considerable increase in thickness, whereas the outer and middle layers had remained essentially unchanged. Finally, in fully keratinized cells, the outer layer of the plasma membrane was not always demonstrable, so that in these cells the plasma membrane seemed to be composed of a single thick, dense layer of membrane material. The possible implications of these membrane alterations in the total process of keratinization are discussed.
Distribution and fine structure of globule leucocytes in respiratory and digestive tracts of the laboratory rat
Authors: Kent John F. 
Published: February 2005

AbstractStudy of an unselected population of adult laboratory rats demonstrates the presence of globule leucocytes in the bronchioles, bronchi, trachea, larynx and oropharynx. In the digestive tract, these leucocytes are seldom found in the antral part of the stomach but are abundant in the glandular stomach where they have been confused with mast cells. Numerous globule leucocytes also occur in the large and small intestines. Although most of these leucocytes are located in the epithelium rather than the connective tissue of themucous membranes of these organs, this pattern is reversed in the small intestine of normal rats. Globule leucocytes are present in essentially normal numbers in the trachea and larynx of axenic rats, but are less abundant than normal in the small intestine of these animals. The fine structure of the globule leucocyte and its characteristic inclusions is compared with that of other similar or possibly related cells and with that of the globule leucocyte of the fowl described recently by Toner.
Maternal behavior in the rat: Survival of newborn fostered young after hormonal treatment of the foster mother
Authors: Zarrow M. X. , Grota L. J. , Denenberg V. H. 
Published: February 2005

AbstractThe 10‐day old natural young of lactating rat mothers were removed, and the mother was given newborn foster young together with hormone treatment. A single injection of prolactin or progesterone was sufficient to increase the survival perentage and body weight of the fostered rats. An hypothesis is presented to explain the action of the hormones and the possible relationship to placental eating which is noted in many mammals at the time of parturition.
The morphology of valves in cerebral arteries of the rat
Authors: Rosen William C. 
Published: February 2005

AbstractValves associated with major arterial branches at the base of the brain in rats were studied after fixation by perfusion with buffered aldehydes. These endothelial covered structures are entirely intimal. All cellular and non‐cellular elements of their core are laminated, including the PAS positive ground substance. Smooth muscle and nerve endings are not demonstrable. Reticular fibers form a substantial sheath around the base of each valve. Their location and morphology suggest that they may serve a regulatory function in maintaining proper intracerebral blood flow.
Cell proliferation in the mammary gland during late pregnancy and lactation
Authors: Traurig Harold H. 
Published: February 2005

AbstractNulliparous, CFW mice were injected with 25 m̈c of tritiated thymidine on day 19 of pregnancy, and days 1, 2, 3, 5, 7, 10, 15 and 20 of lactation. The animals were killed one hour after injection. The inguinal mammary glands were removed and processed for paraffin sectioning. Radioautographs were prepared, using the dipping technique.Quantitation of mammary epithelial cell proliferation for the intra‐ and interlobular (ducts) epithelium was performed by determining the percent of labeled epithelial cells in a large sample of cells (labeling index). It was concluded that epithelial cell sample sizes of 1,000–2,000 cells were adequate to measure mammary epithelial proliferation. A wave of epithelial proliferation was observed during early lactation. In the intralobular epithelium, a peak labeling index of 11.1% was attained on day two of lactation whereas a peak labeling index of 7.9% was observed on day three of lactation in the interlobular epithelium. Cells of the connective tissue and vascular bed proliferated in response to the growth of the mammary epithelium. Myoepithelial cells were frequently labeled on days two and three of lactation.
A radioautographic study of proliferation in brown fat of the rat after exposure to cold
Authors: Hunt Thomas E. , Hunt Eleanor A. 
Published: February 2005

AbstractRadioautographs of the interscapular brown fat of six weeks old animals showed that within 24 hours after cold exposure at 4°–5°C, proliferation increased in endothelium of the already profuse capillary network and also that of arterioles and especially that of venules. This continued at a high level for 48 hours then declined. Extravascular fat precursor cells but not fat cells showed an increased proliferative activity at 48 hours cold exposure which continued until 96 hours. By eight days, adaptation to the cold occurred and proliferative activity was not increased thereafter nor did it occur significantly in animals seven months old. Animals exposed to cold 48 hours, given thymidine‐H3, and then returned to a temperature of 23°C for a week or more showed a considerable number of labeled fat cells which presumably were precursor cells when the thymidine‐H3 was given. When the interscapular brown fat was denervated on one side, there was no loss of lipid nor increased proliferative activity in the vascular or extravascular cells on that side after 48 hours cold exposure. The normally innervated opposite side, however, had more proliferating cells than usual, especially in the endothelium.
Interneocortical connections in the opossum, Didelphis virginiana
Authors: Martin George Franklin 
Published: February 2005

AbstractDiscrete neocortical lesions were placed in the brains of 12 opossums. After a survival time of 1 to 3 weeks, the brains were subjected to the Nauta‐Gygax technique for degenerating axons or to the Swank‐Davenport modification of the Marchi technique for degenerating myelin. A partial hemispherectomy was performed on the brains of two additional animals. The entire intact hemisphere opposite the lesion was then subjected to the Nauta‐Gygax technique.The results of histological examination indicate that fibers cross extensively in the anterior commissure from all areas of the neocortex. Degenerating fibers passed from each of the neocortical lesions into the ipsilateral external capsule. It was by means of the external capsule that they entered the anterior commissure. After crossing in the anterior commissure, the degenerating fibers passed into the contralateral external capsule and subsequently terminated on cells in the homotypic cortex opposite the lesion. Some fibers, however, terminated in non homotypic cortical areas. Fibers, particularly from the more dorsally placed lesions, also crossed in the hippocampal commissure. The results support the concept that a portion of the anterior commissure of certain marsupials is homologous to the corpus callosum of higher forms.
Regeneration of resected calcaneal tendon of the rabbit
Authors: Conway Anna M. , Dorner Robert W. , Zuckner Jack 
Published: February 2005

AbstractA connective tissue growth model based on the regeneration of rabbit calcaneal tendon following surgical excision is described. Tissues allowed to regenerate for various periods of time from two days to 240 days were studied histologically and compared with mature tendon.Rabbit calcaneal tendon regenerating for 14 days or longer was found to represent a rapidly grown, normal connective tissue obtainable in quantities sufficient for biochemical microanalysis and thus to provide a valuable connective tissue growth model. By allowing growth to proceed for 56 days, the model could be used to provide normal tissue morphologically approximating mature tendon.
Electrophoretic patterns of proteins in the blastocoelic fluid of the rabbit following ovariectomy
Authors: Sugawara S. , Hafez E. S. E. 
Published: February 2005

AbstractA total of 286 blastocysts were recovered 6 to 8 days post coitum (p.c.) from untreated or ovariectomized rabbits. The weight of the blastocyst and the volume of the blastocoelic fluid increased at a linear rate from seven to seven and one‐half days p.c., thereafter they increased more rapidly. The weight of the embryonic tissue did not change appreciably between seven and eight days p.c. The appearance of protein in the fluid was dependent on the stage of development, albumin being first detectable at six days p.c. Seven days p.c., β‐globulin was detectable, followed by α‐ and γ‐globulins (seven and one‐quarter days p.c.) and fibrinogen (seven and one‐half days p.c.). Seven and one‐half days p.c., the electrophoretic distribution of proteins was qualitatively similar to that of the maternal serum and peritoneal fluid, however, quantitatively different. Ovariectomy at six days p.c. had no effect 24 hours later on blastocyst growth or blastocoelic fluid volume. In contrast, ovariectomy at six and one‐half days p.c. had a negative effect 24 hours later on blastocyst growth, blastocoelic fluid enhancement and albumin accumulation in the fluid. These latter three phenomena were alleviated by administration of progesterone.
Electron microscopic observations on the membrane systems of the rat blood platelet
Authors: Behnke O. 
Published: February 2005

AbstractRat blood platelets have two membrane systems in their cytoplasm. One, named the surface connected system (SCS), consists of vacuoles and large cavities which are in continuity with the plasma membrane. The inner surfaces of the membranes of this system have, in common with the plasma membrane, a thin coat of an amorphous substance which probably consists of acid mucopolysaccharides.The other system, named the dense tubular system (DTS), consists of slender membrane‐bound tubules which contain a homogeneous, rather electron dense substance. The DTS is not continuous with the plasma membrane or the SCS.Rat blood platelets incorporate various foreign substances in vivo and in vitro; these substances are first adsorbed to the amorphous cell coat and subsequently taken into the SCS.It is suggested that the uptake of material by rat blood platelets reflects a membrane flow from the surface membrane to the SCS, and that the process is not phagocytic in nature since segregation and digestion of the incorporated material do not seem to take place.
The junctional specializations of sertoli cells in the seminiferous epithelium
Authors: Flickinger Charles , Fawcett Don W. 
Published: February 2005

AbstractAttention is directed to an unusual type of junctional complex between Sertoli cells in the seminiferous epithelium. The space between the membranes of adjoining cells is narrowed to 70–90 Å over large areas of their contact surfaces. In the superficial cytoplasm of each cell is an extensive cisterna of the endoplasmic reticulum, parallel to the membrane and 400–600 Å from it. Spaced at more or less regular intervals in the thin layer of cytoplasm between the cisterna and the cell membrane are periodic densities that appear to be band‐like aggregations of fine filaments. The sub‐surface cisternae are smooth‐contoured on the side toward the cell membrane but bear ribosomes on the side facing the cytoplasm. The possible significance of these distinctive junctions is discussed in relation to the support of the germ cells and the coordination of the developmental events in the cycle of the seminiferous epithelium.