bluuebunny/crossref_metadata_2025_split huggingface dataset:
Renewal of the epithelium in the descending colon of the mouse. I. Presence of three cell populations: Vacuolated‐columnar, mucous and argentaffin
Authors: Chang W. W. L. , Leblond C. P. 
Published: February 2005

AbstractThe epithelium of the descending colon was examined in the mouse using one‐micron thick Epon embedded sections of formaldehyde‐fixed tissues stained with the periodic acid‐Schiff and iron‐hematoxylin techniques, and radioautographed at various time intervals after a single injection of tritium labeled thymidine.Four cell types may be described: vacuolated cells located in the lower twothirds of the crypts, columnar cells in the upper third and on the surface, mucous cells and argentaffin (granule‐containing) cells distributed throughout crypt and surface.One hour after injection of 3H‐thymidine, only some vacuolated and mucous cells are labeled; cells of both types may show mitotic figures, but only in the lower two‐thirds of the crypts.By 36 hours, label appears in cells of the upper third of the crypts; some of these cells are intermediate between vacuolated and columnar, while others are full‐fledged columnar cells. Labeled mucous cells also appear at this level. Occasionally, a labeled argentaffin cell may be found at that time toward the base of the crypts.By three days, labeled columnar and mucous cells are found on the surface. Extrusion of such labeled cells is usually seen toward the fourth day.It is concluded that the epithelium of the descending colon of the mouse includes three cell lines. In the first one, vacuolated cells divide to produce more vacuolated cells, but as they migrate upwards, they lose their vacuoles while ceasing to divide and become typical columnar cells. Together they make up the vacuolated‐columnar cell line. The mucous cells arise from mitosis of cells with a small amount of mucus. As daughter cells migrate upwards, their theca swells, presumably because production of mucus exceeds release, whereas, on the surface, the theca becomes narrow as release predominates. In the third cell line, the argentaffin cells do not divide and appear to originate from poorly differentiated vacuolated cells at the base of the crypts. The latter cells may also give rise to the young mucous cells capable of division. The three cell lines would thus have a common stem cell.
Renewal of the epithelium in the descending colon of the mouse. III. Diurnal variation in the proliferative activity of epithelial cells
Authors: Chang W. W. L. 
Published: February 2005

AbstractThe rate of proliferation of epithelial cells in the descending colon was investigated in four groups of adult mice sacrificed one hour after injection of 3H‐thymidine respectively at 04:00, 10:00, 16:00 and 22:00 h of the day. Semithin (1 μ) Epon embedded sections of the colon were radioautographed after staining with periodic acid‐Schiff and iron‐hematoxylin.Measurement of the number of mitoses as well as the labeling indices show a diurnal variation in the rate of proliferation of both vacuolated and mucous cells. The peak of mitotic activity in both cell types seems to be around 12:00–13:00 h and the nadir around 20:00–22:00 h.In the vacuolated‐columnar cell line, the rate of proliferation of the poorly differentiated cells at the base of the crypt is not much influenced by diurnal variation, while that of the more differentiated cells located higher up is. Mucous cells, which are believed to originate in the poorly differentiated vacuolated cells in the lower portion of the crypt, are also strongly affected. Therefore, the more differentiated cells are, the more susceptible they are to diurnal variation in mitotic activity.The number of epithelial cells lining the crypt varies throughout the day in a similar manner as the rate of cell proliferation. A slight daily variation is also noted in the number of cells in the surface epithelium. These variations are accounted for by a delayed effect of the population pressure resulting from the mitotic peak. The numbers of vacuolated‐columnar and mucous cells vary like those of the whole epithelial population, while argentaffin cells fluctuate more widely. In any case, the three main cell lines of the descending colon of the mouse are influenced to some extent by diurnal variations.
A morphological study of the development of the human liver. I. Development of the hepatic diverticulum
Authors: Severn Charles B. 
Published: February 2005

AbstractThe development of the hepatic diverticulum was examined in 38 human embryos representing somite stages 1, 5, 8 and 10 through 29, inclusive. Interpretations were based on light microscopic study of serial sections of these embryos.The liver primordium was first identified in a five‐somite embryo as a flat plate of endodermal cells continuous with, but lying ventral to, the endoderm of the foregut at the anterior intestinal portal. It is positioned caudal and ventral to the developing heart. This plate of endoderm subsequently undergoes a progressive folding due to differential growth of adjacent structures. During the folding process there is a close spatial relationship between the cells of the endodermal plate and the caudal and ventral endothelial lining of the atrium and the sinus venosus. The result of this folding is the establishment of a “T‐shaped” diverticulum which projects ventrally and cephalically from the gut tract. The hepatic diverticulum is established by the 20 somite‐stage embryo. This mode of development of the hepatic diverticulum is compared to the classical interpretation and to the development of other visceral organs.
The ultrastructure and cytochemistry of the shell membrane‐secreting region of the Japanese quail oviduct
Authors: Hoffer Anita P. 
Published: February 2005

AbstractThe isthmic mucosa or shell membrane‐secreting portion of the Japanese quail oviduct was examined by light and electron microscopy and by cytochemical techniques. Preliminary studies of the shell membrane were also made.The mucosa of the isthmus is thrown into numerous longitudinal folds which are covered by a simple columnar epithelium consisting of ciliated and mucussecreting cells. Numerous convoluted simple tubular glands lie densely packed beneath the surface epithelium and are connected to it by short ducts. The tubular glands are made up of a single cell type, the principal cell, which contains numerous large secretory granules. Mature granules display an eccentrically placed dense spherical core surrounded by a less dense cortex. The shell membrane is composed of a meshwork of intersecting fibers oriented randomly in the plane of the membrane; each fiber is made up of a medulla and cortex.Cytochemical methods indicate that the principal cell secretory granules consist of a complex of carbohydrate with protein. The protein is rich in sulfhydryl groups; the polysaccharide moiety is neither sulfated nor rich in carboxyl groups. The mucigen granules are composed of a nonsulfated carbohydrate‐containing substance. The shell membrane has both carbohydrate and protein components. Speculations are presented on the morphological relationships between the various components of the completed shell membrane and their secretory precursors.
The opisthonephric kidney of the sea lamprey of the great lakes, Petromyzon marinus L. V. The archinephric duct
Authors: Youson John H. , McMillan Donald B. 
Published: February 2005

AbstractThe archinephric duct of ammocoetes consists of two morphologically distinct regions. An anterior and posterior region are lined by a columnar epithelium that often possesses wide, lateral intercellular spaces. Some cells in the anterior region are characterized by an electron‐dense apical cell coat and dense apical vesicles, while others resemble cells of the collecting tubule. In the posterior region all cells possess large accumulations of glycogen, mitochondria, and smooth endoplasmic reticulum. There is reason to believe that transport of ions and fluids may occur in the duct and, although some morphological evidence indicates a role in protein absorption, these cells do not appear to be specialized for this function.The archinephric duct of the adult lamprey is morphologically distinct from that of the ammocoete and appears to be involved in the production of mucus and in the expulsion of urine by contraction of its muscular wall. Its stratified epithelium is divided into basal, intermediate, and superficial cells and intracellular PAS‐positive granules increase progressively in number from the basal to surface cells. The superficial cells can be further divided into four types and a progression of cell types from the base to the surface of the epithelium is suggested. A thick electron‐dense apical cell coat, apical vesicles, and mucous granules probably account for the intense staining of the surface with PAS. These features indicate that a closer structural relationship exists between the lamprey archinephric duct and the excretory ducts of other lower vertebrates than with the ureter of mammals.
A comparison of the morphology of lipid absorption in the jejunum and ileum of the adult rat
Authors: Jersild Ralph A. , Clayton Robert T. 
Published: February 2005

AbstractMorphological aspects of lipid absorption were compared in the jejunum, mid‐ and terminal ileum. Physiological fatty chyme was injected into ligated segments of each of the intestinal regions in fasting rats. Tissues were removed at intervals from 5 to 30 minutes and prepared for electron microscopy. The results show the morphological pattern of lipid accumulation to be similar in the jejunum and mid‐ileum. Both show evidence for considerable lipid absorption and transport. The terminal ileum, in contrast, displays an altered pattern of lipid distribution. Numerous lipid droplets begin to form at an early time period in the cytoplasmic matrix, as in the upper intestine. These droplets become larger and more numerous as absorption progresses. Lipid droplets in the endoplasmic reticulum and Golgi apparatus, however, are present in considerably reduced size and numbers through the entire absorptive period examined, as compared to the upper intestine. Few droplets are present in the lamina propria. Considerably less transport of absorbed lipid is indicated. This morphological pattern appears to correlate with a reduced synthesis of triglycerides in the terminal ileum. The evidence suggests that triglyceride synthesis and the formation of membrane‐bound droplets are related events as they normally occur in the upper small intestine.
Localization of obturator and pectineal motoneurons in the dog
Authors: Breit James F. , Cardinet George H. , Tunell Gary L. , Fedde Marion R. 
Published: February 2005

AbstractThe motoneuron columns of the obturator and pectineal nerves were localized within the lumbar spinal cords of dogs by observing retrograde chromatolysis following resection of the respective nerves. The obturator column was located in segments L4 through L6 while the pectineal column was located in segments L4 and L5. The dorsal‐to‐ventral and medial‐to‐lateral boundaries were determined for each column and the pectineal column was located within the boundaries determined for the obturator column in segments L4 and L5. Antidromic stimulation of the pectineal nerve localized the origin of motor fibers from lumbar spinal nerves L4 and L5. The results provide an anatomical basis for studies of motoneurons innervating the pectineus muscles of dogs affected with a developmental myopathy of this muscle.
Myoepithelial cells in the exorbital lacrimal and parotid glands of the rat in frozen‐etched replicas
Authors: Leeson Thomas S. , Leeson C. Roland 
Published: February 2005

AbstractLight and electron microscopy were combined with the technique of freeze‐etch to study myoepithelial cells. Myoepithelial cells of the rat exorbital lacrimal and parotid glands are found in relation both to secretory units and intercalated ducts. They lie within the basal laminae of secretory acini and intercalated ducts and do not protrude from the external surface. The myoepithelial cell consists of a central nucleus and surrounding cytoplasm with several cytoplasmic arms, the arms being less numerous in those cells associated with the ducts. The cytoplasm is filled with fine fibrils in parallel array. The interrelationship between myoepithelial cells and acinar or ductal cells is described with the aid of frozen‐etched replicas and the nature of the membrane surfaces is discussed. It is concluded that myoepithelial cells are contractile; their resemblance to smooth muscle is noted.
The vertebral‐basilar system of dog in relation to man and other mammals
Authors: Anderson Wesley D. , Kubicek William 
Published: February 2005

AbstractThe basilar artery of the dog was studied and its branches traced to their terminations. The nomenclature used is based on the origin, course and termination of the arteries. The basilar artery arose from a spinal arterial circle formed in the vertebral canal at the level of the atlanto‐occipital articulation by union of vertebral arteries and the ventral spinal artery. The arterial supply to the membranous labyrinth arose from the anterior inferior cerebellar artery. After entering the porus acusticus, one or more tiny labyrinthine arteries arose and the parent trunk then looped dorsally out of the meatus to supply the lower portions of the cerebellum. A branch of the basilar artery, unnamed in the dog, was associated closely with the trigeminal nerve; a separate arterial supply to the caudal colliculus arose from the medial branch of the superior cerebellar artery. It was concluded that branches of the basilar artery of the dog and man are similar since, with exception of the middle inferior cerebellar artery, all branches of the basilar artery in man may be found in dog.
The histochemical and microscopical differentiation of the respiratory glands around the maxillary sinus of the rat
Authors: Vidić Branislav , Greditzer Harry G. 
Published: February 2005

AbstractTo investigate the histochemical and microscopical characteristics of the lateral and maxillary glands, as well as their topographical relationship with the maxillary sinus, 25 adult specimens were used. The tissues were fixed in neutral buffered formalin and serial sections were stained with hematoxylin and eosin, trichrome, Sudan black B, ninhydrin‐Schiff, PAS, alcian blue, and mucicarmine. The objectives were to ascertain: (1) the general morphology of the lateral nasal wall and of the maxillary sinus, (2) the topographical relation between the glands and the maxillary sinus, (3) the microscopical and histochemical characteristics of the maxillary gland, and (4) the microscopical and histochemical characteristics of the lateral nasal gland. In all specimens, the sinus was surrounded by glandular tissue. The lateral gland occupied the submucosa anterior and inferior to the sinus, the maxillary gland extended from the anterior to the posterior recess superior to the sinus. The maxillary gland showed the typical morphology characteristic of a serous gland. The gland drained into the sinus by numerous excretory ducts. The epithelium of the proximal ducts was simple columnar and in the distal ducts, pseudostratified columnar ciliated. The latter type of epithelium, without goblet cells, was found in the maxillary sinus. The lateral gland showed a morphology characteristic of mucous glands. Although the gland contained neither free lipids nor proteins, it was PAS‐positive. A high concentration of acid glucoproteins was detected in the lateral gland. The excretory system of this gland was lined throughout by either a simple columnar or a simple cuboidal epithelium. The possible contribution of the glands to the functioning of the upper part of the respiratory system was discussed.
Ultrastructura observations on ovarian perifollicular smooth muscle in the cat, guinea pig, and rabbit
Authors: Burden Hubert W. 
Published: February 2005

AbstractThe theca externa of large vesicular ovarian follicles of cats, rabbits and guinea pigs was studied with the electron microscope. Fibroblasts and smooth muscle were observed in all species. In the guinea pig, a third cell type, with characteristics of both fibroblasts and smooth muscle, was present. Myelinated and unmyelinated nerves were observed in the theca externa of cats and guinea pigs. Unmyelinated nerves often contained vesicles and mitochondria and were separated from cellular elements by a space of about 2000 Å. It is suggested that coordinated muscular contractions in the theca externa offer the most reasonable explanation for the extrusion of the ovum. This muscle is probably, at least partially, under local neural control.
An electron microscopic study of sperm penetration into the rabbit egg after natural mating
Authors: Bedford J. M. 
Published: February 2005

AbstractThe ultrastructure of fertilization has been studied in rabbit eggs recovered 11 to 15 hours after natural mating. Many sperm passing between the granulosa cells had undergone the acrosomal reaction, but this was not invariable, and, occasionally, intact sperm were present close to the zona pellucida. The cells of the corona radiata sometimes develop pseudopodial processes at the abovular surface and can ingest sperm after natural mating. The bulk of the content of the acrosome and the vesiculated elements formed during the acrosomal reaction, are lost before the sperm penetrates the zona pellucida, at which point the naked inner membrane of the acrosome is brought into intimate apposition with the zona. As the sperm cleaves a path through the zona pellucida, the posterior equatorial segment of the acrosome remains intact, and later persists as such in perivitelline sperm and quite possibly after incorporation of the sperm head into the vitellus.Sperm head entry into the vitellus is a two‐fold process. The fertilizing sperm invariably fuses first with the vitelline membrane over the midposterior region of the head, whereas the rostral or acrosomal portion is drawn into the vitellus while encased by a flattened vesicle; this vesicle is comprised by the persistent inner membrane of the acrosome and externally by vitelline membrane sequestered from the egg surface. Soon after exposure to ooplasm, the sperm nucleus begins to decondense at a variable rate into a web of electron‐dense strands; this process begins in the midposterior region, and then extends rostrally and caudally. At the same time the encasing membranes are reflected away from the anterior region of the nucleus, exposing subacrosomal material to the ooplasm. At this point the perforatorium remains, but this and the associated membranes are presumed to disintegrate eventually within the egg. After decondensation of the nucleus is complete, the faintly staining chromatin becomes enveloped by a series of compressed vesicles which together will form the porous limiting membrane of the male pronucleus.The last region to be incorporated is the sperm tail, the plasma membrane of which is lost as organelles of the tail pass into the ooplasm. During its incorporation, the midpiece engenders some reaction at the egg surface, and the mainpiece sometimes becomes fused with surface processes before it enters the body of the egg. The midpiece then commonly disintegrates, with dispersion of the mitochondrial sheath, whereas the mainpiece usually remains essentially intact until the time of syngamy or beyond.
Skeletal muscle regeneration in young rats
Authors: Walker Bruce E. 
Published: February 2005

AbstractThe source of myotube nuclei in regeneration of skeletal muscle in young rats was studied by comparing frequencies of labeled nuclei in two experiments. In a single injury experiment, multiple injections of thymidine‐H3 were given during a three day period, skeletal muscle was injured 12 days later and the rats were killed four days after injury. There were almost no labeled myotube nuclei in this experiment. In a double injury experiment, thymidine‐H3 was injected two days after injury, the muscle was reinjured 12 days later, and the rats were killed four days after the second injury. Half of the myotube nuclei were radioactive and most of the centrally placed nuclei in maturing muscle fibers from the initial injury were radioactive. Since nuclei at the periphery of muscle fibers, including satellite cell nuclei, would have been labeled in both experiments, whereas myonuclei were extensively labeled only in the double injury experiment, it was concluded that the myotube nuclei were derived mainly from myonuclei.
Mast cells, compound 48/80, and prolonged hypothermia in the rat
Authors: Rink Richard D. 
Published: February 2005

AbstractIn the nonhibernating animal the stress of prolonged deep hypothermia is associated with the development of circulatory symptoms like those of burn‐shock. Mast cells are sensitive to a variety of stressors, including thermal ones, and commonly react by releasing vasoactive substances that may facilitate vascular changes similar to those of burnshock. The possible role of mast cells in the complications of prolonged hypothermia was the object of this investigation.Two groups of female albino rats were subjected to 15° C total body hypothermia for 7.5 hr and then rewarmed artificially. Group I had been treated previously with compound 48/80 which depletes the mast cell content of tissues. Group II constituted controls and possessed a normal complement of mast cells.Progressive hemoconcentration was noted in both groups. However, the hematocrits of the 48/80‐treated animals were significantly lower at selected intervals than those of control animals. In addition, 100% survival of the 48/80‐treated animals was recorded in contrast to a 60% survival rate for controls. Microscopic examination of the mast cells in several tissues of additional controls suggested a loss of granule density during hypothermia and early rewarming. This investigation offers circumstantial evidence that mast cells of the rat facilitate the development of some of the deleterious effects of prolonged hypothermia.
The development of capillaries in the villi of early human placentas
Authors: Dempsey Edward W. 
Published: February 2005

AbstractElectron microscopic examinations have been made on 32 early human placentas, seven of which ranged from 7 to 11 weeks menstrual age. In avascular villi, well developed basal laminae separate the trophoblast from their connective tissue cores. At such stages, only undifferentiated mesenchymal cells occur in the stroma. Vessels develop by attachment of two or more of the mesenchymal cells to each other by localized desmosomal contacts, thus forming a real or potential capillary lumen between their apposed plasma membranes. Other mesenchymal cells approach these primitive tubes, enclasp them as pericytes, and thrust processes between adjacent endothelial cells at their attachment points. The capillary enlarges, therefore, by incorporation of mesenchymal pericytes between adjacent endothelia. Mitoses occur in the pericytes but not in early endothelial cells. Hofbauer cells differentiate in the stroma concomitantly with the appearance of capillaries.