bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic histology of the antral epithelium in the mouse stomach: V. Proliferation gradient from the gland base to the isthmus at various times of day
Authors: El‐Alfy M. , Leblond C. P. , Lee E. R. 
Published: February 2005

AbstractThe surface epithelium of the mouse pyloric antrum invaginates into blind‐ended tubules whose proliferative activity was investigated by using light microscopy and 3H‐thymidine radioautography. Adult, male, CD1 mice were habituated to 12 hr of light (0600–1800hr) alternating with 12 hr of darkness. Groups of four were given an injection of 40 μCi of 3H‐thymidine per animal and killed 1 hr later at 0600, 1200, 1800, and 2400 hr. The glands at the base of the tubules and the adjacent isthmi were serially cross‐sectioned, and 0.5‐μm‐thick sections were prepared for radioautography. By using morphological criteria, glands were divided into five levels from their base to the isthmus (which was considered as being a sixth level). Proliferative activity was estimated by measuring the proportion of cells incorporating 3H‐thymidine (labeling index) and the proportion of cells undergoing mitosis (mitotic index).The labeling index was found to decrease gradually from a high value in the isthmus to a relatively low one in the gland base; and this was observed at four times of the day. Similar gradients were observed in the mitotic index. Moreover, significant circadian variation was disclosed at most levels by comparing either labeling or mitotic index at four different times of the day. The labeling index tended to peak at the transition from dark to light (0600 hr) and drop at the transition from light to dark (1800 hr). In contrast, mitoses usually reached a maximum at the end of the light cycle (1800 hr) and a minimum at 2400 hr.In summary, the rates of DNA synthesis and cell division showed a sharply decreasing gradient of cell proliferation from the immature cells of the isthmus (level 6) to the mature cells of the gland base (level 1). The existence of some degree of proliferation, even in mature cells, sets apart the renewal taking place in the isthmus‐gland system, since in other renewal sites, cells stop dividing before they reach maturity. Finally, circadian variation has been identified in the proliferative activity of isthmus and gland and appears to be closely related to the light‐dark cycle.
Comparative study of cytoplasmic elimination in spermatids of selected mammalian species
Authors: Sprando Robert L. , Russell Lonnie D. 
Published: February 2005

AbstractIn the transformation of a spermatid into a spermatozoon, cytoplasmic loss occurs, allowing the sperm to swim unhindered. Cytoplasmic loss takes place via elimination of the residual body and through structures known as tubulobulbar complexes. A determination of cytoplasmic loss in several species was undertaken by using high‐resolution electron microscopic morphometric techniques. During the period that tubulobulbar complexes are present, an average 53% cytoplasmic loss was recorded for five species (guinea pig, 48.8±6.2% (SEM); monkey, 60.3±4.3%; opossum, 54.5±4.4%; rabbit, 46.9±2.7%; and rat, 55.7±4.9%), whereas there was essentially no loss or gain in cytoplasm during the same period for round spermatids. Surprisingly, during spermatid elongation an approximate 36% loss of cytoplasm was also recorded for five species (guinea pig, 50.1±6.3%; monkey, 30.0±15.4%; opossom, 25.4±9.0%; rabbit, 42.4±8.6%; and rat, 34.9±11.9%), which is only partially (∼60%) accounted for by fluid pumping from the nucleus during nuclear condensation. A densification of the cytoplasm of elongate spermatids, as compared with round spermatids, suggests fluid is also pumped from the elongating spermatid cytoplasm. Fluid loss from germ cells may contribute to the seminiferous tubule fluid, a fluid previously thought to be solely of Sertoli‐cell origin.
Presence of α‐melanocyte‐stimulating hormone in bovine pituitary intraglandular colloid of intermediate lobe origin
Authors: Boyd William H. , Krogsrud R. L. 
Published: February 2005

AbstractAlpha‐melanocyte‐stimulating hormone (α‐MSH), one of several peptide hormones originating in the intermediate lobe of the pituitary as proopiomelanocortin, was discovered in bovine pituitary intraglandular colloid by using radioimmunoassay. The quantity of α‐MSH varied from 5 to 368 μg/mg protein in the three pools. The importance of this finding is discussed in light of the possibility that the colloid is a transport medium for α‐MSH and other intermediate lobe hormones.
Ultrastructural demonstration of exocytosis in intact and saponin‐permeabilized cultured bovine chromaffin cells
Authors: Brooks Jack C. , Carmichael Stephen W. 
Published: February 2005

AbstractExocytosis is the release of intracellular vesicular contents directly to the cell exterior after fusion of the vesicular and plasma membranes. It is generally accepted as the process by which transmitters and hormones are released from neurons and neurosecretory cells. There is overwhelming biochemical evidence that exocytosis is the mechanism by which catecholamines are released from adrenal chromaffin cells. With the exception of the hamster, however, there is little ultrastructural evidence to support such a mechanism. We have used a modified in vitro tannicacid method to visualize exocytosis by transmission electron microscopy in intact and saponin‐permeabilized bovine chromaffin cells. When cells are exposed to tannic‐acid‐containing medium, the content of vesicles involved in exocytosis is coagulated in situ as the vesicle opens to the exterior. Numerous exocytotic profiles were observed. The exposed vesicle contents appeared more granular than those of vesicles in the cell interior. Tannic acid also made the plasma membrane more distinct. Small holes were apparent in the plasma membrane of saponin‐treated cells, with little disruption of underlying cytoplasmic structure. Furthermore, when these cells were stimulated with calcium, exocytosis was evident only at regions of intact plasma membrane, not at the holes. Parallel measurements of secretion showed no secretion in the presence of tannic acid. Pretreatment with tannic acid prevented subsequent secretion by intact cells and markedly reduced that of permeabilized cells, indicating a probable change in the nature of the plasma membrane. Our results provide the first ultrastructural demonstration of exocytosis in bovine chromaffin cells with the aid of transmission electron microscopy. It is also clear that exocytosis is the mechanism of release in both intact and permeabilized cells.
Restricted growth at the frontonasal suture: Alterations in craniofacial growth in rabbits
Authors: Babler William J. , Persing John A. , Nagorsky Mathew J. , Jane John A. 
Published: February 2005

AbstractApposition of bone at the sutural margin is generally thought to be a compensatory adjustment to growing soft‐tissue organs such as the brain or eyes within the skull. The frontonasal suture which is located at the interface between the cranial and facial skeletons is a site of extremely active growth in the young rabbit. Recently, we showed that premature closure of a cranial suture, the coronal suture, can alter the growth not only at the adjacent frontonasal suture but also of the basicranium and midface. This study examines the effects of restricted growth at the frontonasal suture on both growth at adjacent cranial sutures and linear growth of the basicranium and midface.Thirty newborn New Zealand White rabbits were subdivided into experimental and sham‐treated groups of equal size and distribution for sex and birth weight. At 9 days of age, the frontonasal suture of each experimental animal was immobilized by bilateral application of methyl‐cyanoacrylate adhesive across the frontonasal suture. Growth and morphometric changes were monitored by radiocephalometric methods through 120 days of age by bilateral implantation of radiopague markers on each side of frontonasal, coronal, and anterior lambdoid sutures.Results indicate that restricted growth at the frontonasal suture results not only in a significant shortening of the midface but also in significant decreases in growth at the coronal and internasal sutures. Growth at the interfrontal and sagittal sutures is increased. Furthermore, growth at the anterior portion of the nasal bones is significantly increased, thereby offsetting a portion of the decreased nasal bone length resulting from frontonasal restriction.
Quantitative immunocytochemical analysis of the endocrine pancreas of the Nile crocodile
Authors: Rhoten William B. 
Published: February 2005

AbstractFour major pancreatic hormones were immunolocalized at the light and electron microscopic levels in the pancreas of the Nile crocodile, Crocodilus niloticus. Immunogold was used for electron microscopy, and peroxidase‐antiperoxidase was used for light microscopy. Somatostatin‐positive D‐cells and pancreatic polypeptide‐containing F‐cells accounted for about 60% of the immunoreactive cells in the ventral pancreas. Glucagon‐positive A‐cells were the least frequent cell type in the ventral pancreas, about 15%, but were the predominant cell type, about 40%, in the pancreas that was dorsal in character. An expanded population of D‐cells (relative to mammals and other higher vertebrates) in association with two very different numbers of A‐cells can be expected to have important consequences for the homotropic control of secretory activity of the endocrine pancreas as well as for the function of the acinar pancreas. F‐cells were absent from the dorsal part of the pancreas, whereas insulin‐containing B‐cells were slightly more abundant in this portion of the pancreas. The regional character of the endocrine pancreas was related to the complex looping of the proximal small intestine.Without immunolabeling, only B‐granules were morphognomonic in electron micrographs. The insulin‐reactive B‐granules were the smallest (370 nm) of the secretory granules and were followed in size by somatostatin‐positive D‐granules (380 nm). The pancreatic polypeptide‐containing secretory granules were the largest (580 nm). Glucagon‐reactive A‐granules (430 nm) sometimes exhibited a protuberance or extension of secretory granule matrix and limiting membrane. Such a morphological feature has previously been associated with secretion of glucagon and the initiation of insulin secretion. Taken together these studies indicate that protuberances have a significant, but as yet undefined, role in pancreatic endocrine cells.
Maturation of myocardial capillaries in the fetal and neonatal rat: An ultrastructural study with a morphometric analysis of the vesicle populations
Authors: Porter Glyn A. , Bankston Patrick W. 
Published: February 2005

AbstractThe ultrastructural morphology of the cellular and extracellular components of the developing myocardial capillary wall—from the 16‐day‐gestation fetus of the rat to the 21‐day neonate—was examined. A morphometric analysis of plasmalemmal vesicles and of coated vesicles and pits of capillary endothelial cells was performed during the same developmental period. As the lateral extensions of the capillary endothelial cells change from irregular to regular in their thickness during development, there is an increase in the number of plasmalemmal vesicles and a progression from clusters of plasmalemmal vesicles to a uniform distribution in the endothelial cell. The ratio of vesicles which are open to the luminal front, which are “free” in the cytoplasm, or which are open to the abluminal front of the endothelial cell was consistent throughout development. The numerical density of plasmalemmal vesicles demonstrates a gradual and significant increase. In contrast, the numbers of coated vesicles and pits are variable within a very narrow range, and no pattern of increase or decrease is discernible during development. Similarly, there is no change in interendothelial cell junctions, which consist of occluding and primitive adhesive junctional types, during development. The lamina densa of the basal lamina gradually develops from discontinuous, patchy densities along the abluminal surface of the endothelial cells to a continuous and distinct layer by 21 days gestation. The presence of the proteoglycan species in the developing basal lamina was assessed with the cationic dye ruthenium red (RR), and the appearance of RR‐marked proteoglycans was found to parallel the appearance of lamina densa material. The RR sites appear discontinuously in patches; and later, the RR sites appear in a continuous and regular planar lattice in the lamina rara interna and externa at 21 days gestation. A complete array of RR‐stainable anionic sites outside a continuous lamina densa near birth indicates that the basal laminae of developing capillaries in the heart are morphologically, and in part biochemically, mature by the end of the first neonatal week.Our results show that the endothelial cells and the subtending basal lamina of myocardial capillaries gradually mature morphologically during the final days of gestation and the first neonatal week. The finding of tight junctions and small areas of vesicle concentration in fetal endothelial cells could indicate that sites of permeability are limited early in myocardial capillary development and that these vesicular sites increase as gestation proceeds and as the myocardial capillaries mature.
Ultrastructure of the choroid plexus epithelium of pigeons treated with drugs: I. Effect of thyradin, 2,4‐dinitrophenol, and cycloheximide
Authors: Koshiba Kimikazu 
Published: February 2005

AbstractPossible changes in the epithelial cells of the pigeon choroid plexus induced by administration of thyroid powder (Thyradin), 2,4‐dinitrophenol, and cycloheximide were studied by scanning and transmission electron microscopy. A marked increase in the number of large bulbous and bleblike protrusions on the apical end of the epithelial cells was observed after oral administration of Thyradin for a month. The endoplasmic content of the protrusions consisted mainly of electron‐lucent material. These results provide morphological evidence for the stimulatory effect of Thyradin.Intramuscular injections of 2,4‐dinitrophenol for 15 days caused the collapse or deformation of the mitochondria and bleblike or bulbous protrusions. This indicates that changes in the surface configuration of the choroid plexus are controlled by an energy‐dependent mechanism. The decrease of protrusions and polyribosomes and increase of the tubular saccules of varying electron density, size, and shape were noted in cells after 15 days of intramuscular cycloheximide injection. The electron density of the protrusions is lower than that of the control pigeons.The results of this study suggest that a curious pleomorphic structure on the apical surface of the choroid epithelial cell of pigeon is closely related to the functional state of choroidal cells. The study also demonstrates that a secondary ultrastructural response due to diverse physiologic effects is reflected in the architecture of the choroid plexus cells.
Lung growth of the turkey, Meleagris gallopavo: I. Morphologic and morphometric description
Authors: Timmwood Karen I. , Hyde D. M. , Plopper C. G. 
Published: February 2005

AbstractTo describe lung growth qualitatively and quantitatively from prehatch to adulthood of an unselected line of turkey, a precocial a avian species, 36 male turkeys, three in each age group, were killed at 22 and 25 days of incubation, on hatch day, and at 1, 4, 7, 10, 14, 21, 28, 112, and 420 days of age. Body weight and lung volume were measured. A three‐level cascade sampling system was used to prepare lung tissue for morphologic and morphometric observation by light microscopy. Point and intersection counting were used to estimate volume and surface densities of lung compartments relative to lung volume. Absolute volumes and surfaces of lung compartments were calculated. Bilogarithmic regressions provided allometric equations to describe growth of the lung in three phases: (1) Tissue proliferation—explosive growth of lung volume relative to body weight and of the gas‐exchange compartment within the lung. At 22 days of incubation there were few air and blood capillaries and a great deal of tissue that looked like mesenchyme between the parabronchin. Within the 6 days prior to hatch, the surface area of air capillaries increased 11‐fold and of blood capillaries 27‐fold, whereas the volume of interparabronchial tissue decreased 58%. (2) Equilibrated growth—from hatch day to 28 days of age, most lung compartments grew evenly with lung volume. (3) Regulated growth—from 28 days of age to adult, all lung compartments, except large vessels and exchange compartment, grew more slowly than the entire lung. Interatrial septa lengthened and their epithelial covering thinned, infundibula became more apparent, and interparabronchial connective tissue reached a minimal volume density in the adult lung.
Cells of origin of the branches of the facial nerve: A retrograde HRP study in the rabbit
Authors: Baisden Ronald H. , Woodruff Michael L. , Whittington Dennis L. , Baker Duane C. , Benson Amy E. 
Published: February 2005

AbstractThe origin of different branches of the facial nerve in the rabbit was determined by using retrograde transport of HRP. Either the proximal stump of specific nerves was exposed to HRP after transection, or an injection of the tracer was made into particular muscles innervated by a branch of the facial nerve. A clear somatotopic pattern was observed. Those branches which innervate the rostral facial musculature arise from cells located in the lateral and intermediate portions of the nuclear complex. Orbital musculature is supplied by neurons in the dorsal portion of the complex, with the more rostral orbital muscles receiving input from more laterally located cells while the caudal orbital region receives innervation from more medial regions of the dorsal facial nucleus. The rostral portion of the ear also receives innervation from cells located in the dorsomedial part of the nucleus, but the caudal aspect of the ear is supplied exclusively by cells located in medial regions. The cervical platysma, the platysma of the lower jaw, and the deep muscles (i.e., digastric and stylohyoid) receive input from cells topographically arranged in the middle and ventral portions of the nuclear complex. It is proposed that the topographic relationship between the facial nucleus and branches of the facial nerve reflects the embryological derivation of the facial muscles. Those muscles that develop from the embryonic sphincter colli profundus layer are innervated by lateral and dorsomedial portions of the nuclear complex. The muscles derived from the embryonic platysma layer, including the deep musculature, receive their input from mid to ventral regions of the nuclear complex.
The Golgi apparatus in the acinar cells of the developing embryonic pancreas: I. Morphology and enzyme cytochemistry
Authors: Pavelka Margit , Ellinger Adolf 
Published: February 2005

AbstractThe Golgi apparatus apparatus of pancreatic acinar cells of rat embryos was studied during development from day 13 through day 20 of gestation. The morphological and enzyme cytochemical patterns varied characteristically in the course of cell differentiation. (1) A pronounced system of “rigid lamellae” characterized the area near the trans face of the Golgi stacks in the protodifferentiated and early phases of the differentiated states; by contrast, “rigid lamellae” were sparse in the terminal period of gestation. (2) Reaction product of acid phosphatase labeled the “rigid lamellae” in the protodifferentiated state, was extended across the majority of the stacked cisternae in the early differentiated state, but was restricted to the trans side again in the later periods of cell differentiation. (3) The early phase of the differentiated state was characterized by the tight association of the endoplasmic reticulum and Golgi cisternae on the trans side; the close spatial relationship of the two compartments was lessened after production of secretion granules had started.The findings are in line with those of recent studies on the Golgi organization in some other types of cells in different functional states, and they present the embryonic pancreatic tissue as another model for demonstrating the high flexibility of the Golgi complex. In agreement with the patterns previously found in the absorptive cells of the small intestine, the present results show that the close associations of the endoplasmic reticulum and cisternae of the trans Golgi side predominate in the early stages of cell differentiation.
Characterization of filaments within Leydig cells of the rat testis
Authors: Russell Lonnie D. , Amlani Shahira R. , Vogl A. Wayne , Weber James E. 
Published: February 2005

AbstractRat Leydig cells were permeabilized and the cytoplasm partially extracted to visualize, describe, and characterize filamentous elements of the cytoskeleton. It was demonstrated by immunofluorescence microscopy that vimentin is abundant within Leydig cells. Ultrastructurally, intermediate filaments in Leydig cells were concentrated at perinuclear sites and comprised bundles that coursed through the cytoplasm. Actin was identified in Leydig cells with the F actin probe, NBD‐phallacidin. Fluorescence was strongest at the cortex of the cell. With myosin S‐1 subfragments, sparse actin was found positioned almost exclusively in cortical regions of the cell associated with coated pits and in Leydig cell processes.
Distribution of myelinated nerves in ascending nerves and myenteric plexus of cat colon
Authors: Christensen James , Rick Gary A. 
Published: February 2005

AbstractThe parts of the colon differ in motor function and in responses to extrinsic and intrinsic nerve stimulation. The distribution of myelinated nerve fibers in the colonic myenteric plexus is not known. Because these fibers might be largely extrinsic in origin, their distribution might indicate the domain of influence of extrinsic nerves and help to explain the different behaviors of the different parts of the colon. Myelinated fibers were examined by electron microscopy in cross sections of the ascending nerves and in myelin‐stained whole‐mount preparations in the colon. The ascending nerves are much like one another. They have the structure of peripheral nerves, not that of myenteric plexus. The proportion of myelinated fibers in the ascending nerves declines rostrad with no uniform change in total nerve fiber number. Cross‐sectional areas of ascending nerves, 3,304 to 7,448 μm2; total number of nerve fibers per profile, 703–2,651; and mean myelin coat thickness, 0.45 ± 0.01 μm, do not change uniformly along the ascending nerves. Myelinated fibers are about 2% of total fibers in the extramural colonic nerves, 7–9% in the ascending nerves in the sigmoid colon, and 2–3% at the rostrad ends of the ascending nerves in the transverse colon. Blood vessels lie at the core of each ascending nerve and on the nerve sheath. Myelinated fibers in the ascending nerves degenerate after section of colonic branches of the pelvic plexus and after section of the pudendal nerves, indicating that myelinated nerves reach the colon through both pathways. Myelinated fibers extend into the myenteric plexus through short lateral branches from the ascending nerves to adjacent ganglia where they turn to run cephalad throughout most of the colon but caudad in the rectum. Myelinated fibers do not extend into the cecum or proximal ascending colon. The nonuniform distribution of myelinated fibers along the colon, many of which are extrinsic in origin, could in part explain the disturbances in defecation that sometimes follow limited distal colonic resection, gynecologic surgery, and obstetric damage to the pudendal nerves in man.