bluuebunny/crossref_metadata_2025_split huggingface dataset:
The development of alveolar septa in fetal sheep lung. An ultrastructural and immunohistochemical study
Authors: Fukuda Yuh , Ferrans Victor J. , Crystal Ronald G. 
Published: February 2005

AbstractThe morphogenesis of pulmonary alveolar septa in the sheep was studied by light microscopy, transmission electron microscopy and light microscopic immunohistochemistry for the detection of elastin. The primordia of alveolar septa developed in the glandular stage in areas subjacent to the epithelium, and formed alveolar septa by protruding into the glandular lumina. In their earliest stage, the primordia consisted of groups of fibroblasts, which were associated with elastic fibers and unit collagen fibrils and were surrounded by epithelial basement membrane and by more immature fibroblasts. The fibroblasts in the primordia subsequently became myofibroblasts or smooth muscle cells. In the alveolar zone of the glands, elastic fibers were exclusively found in the primordia of alveolar septa in early developing lung. In early developing lung, wavy, thickened epithelial basement membranes were found in the regions of the glands, which eventually underwent considerable expansion of their surface areas, especially in the primordia of alveolar septa and the bifurcations in the alveolar zones. Areas of fusion of the basement membranes of capillary endothelial cells and epithelial cells in the alveolar zone were found after the formation of the primordia of alveolar septa was accomplished. These areas of fusion were not found in the primordia themselves, but in regions between the primordia. Epithelial cell flattening and differentiation occurred after the formation of the primordia of alveolar septa, and flattening was first observed in the areas of the primordia and the bifurcations of the alveolar zones.
Ultrastructure of the thick ascending limb of henle in the rat kidney
Authors: Kone Bruce C. , Madsen Kirsten M. , Tisher C. Craig 
Published: February 2005

AbstractThe thick ascending limb of Henle (TAL) in the rat until recently has been considered a morphologically homogeneous structure despite physiologic and biochemical evidence to the contrary. The present study was designed to examine the ultrastructural characteristics of the TAL in the inner cortex and the outer and inner stripes of the outer medulla using qualitative and quantitative transmission electron microscopy. Kidneys of male Sprague‐Dawley rats were preserved by in vivo perfusion with glutaraldehyde for light and electron microscopy. The peritubular diameter and cell height were determined by direct measurements on tubule cross sections. Morphometric analyses were performed on montages of tubule cross sections. The peritubular diameter of the TAl was similar in the three regions under investigation, but the TAL cells were taller in the inner stripe than in the inner cortex and outer stripe. Morphometry revealed significant differences between the three regions with respect to the mean tubular cross‐sectional area (AT), the surface density (SV), and the surface area per mm of tubule (ST) of apical and basolateral plasma membranes, and the volume density (VV) of mitochondria. The major morphologic division appeared to be between the inner stripe segment and the remainder of the TAL. These findings document the presence of significant morphologic heterogeneity of the rat TAL.
Epithelial cell differentiation in organotypic cultures of fetal rat lung
Authors: Simpson L. L. , Tanswell A. K. , Joneja M. G. 
Published: February 2005

AbstractThe purpose of this investigation was to examine the suitability of an organotypic lung‐cell culture model for the study of factors influencing fetal lung‐cell differentiation. It has been reported that the use of carbonstripped (hormone‐depleted) bovine fetal calf serum in monolayer cell cultures of fetal rat lung prevents continued epithelial cell differentiation in vitro. In this study, organotypic cultures of fetal rat lung cells taken at day 20 of gestation (late canalicular stage) were prepared with a carbon‐stripped medium. These organotypic cultures were examined by light, scanning, and transmission electron microscopy for comparison with controls prepared with unstripped bovine fetal calf serum. Highly organized three‐dimensional tubular epithelial structures resembling saccules of immature lung were observed within the gelatin sponge matrix. Morphometric analysis of day 20 carbonstripped samples revealed that 74.6% of the epithelial cells in the tubular structures contained osmiophilic lamellar bodies characteristic of type II pneumonocytes. Control specimens had 71.2% cells with lamellar bodies and did not differ significantly from the experimental group. These data are similar to those obtained with organ cultures of fetal rat lung but are in contrast to findings with monolayer culture systems. The observations of this study suggest that (1) the hormones extracted from bovine fetal calf serum by carbonstripping are not solely responsible for the continued fetal lung cell differentiation observed in vitro, and (2) that spatial relationships between lung cells in vitro may be a significant factor in the control of differentiation.
An attempt to differentiate further between microglia and fluorescent granular perithelial (FGP) cells by their capacity to incorporate exogenous protein
Authors: Mato Masao , Ookawara Shigeo , Mato Takashi K. , Namiki Takuo 
Published: February 2005

AbstractIt seems established that under pathological conditions, microglia and blood monocytes (invading the cerebral parenchyma) behave as histiocytic cells in the central nervous system. However, it has not been clear whether or not phagocytic cells are present in normal cerebral tissue. Recently, we found a new type of cell having an uptake capacity for exogenous substance at the bifurcations of small cerebral vessels except for capillaries. According to Imamoto et al. (1982), ameboid microglia, a kind of precursor of microglia, appear at a perinatal stage and can incorporate exogenous material. In the present paper, the developmental sequences of ameboid microglia and the unique cells laden with fluorescent granules are compared at a light and electron‐microscopic level.From this study, it is clear that ameboid microglia are already present in the corpus callosum at 5 days after birth and are potent in their uptake capacity for horseradish peroxidase (HRP). However, at 2 weeks, they transform into star cells and the capacity for incorporation diminishes markedly. The finding is also supported by the quantiative analysis of transformation of ameboid microglia. At 3 months, glial cells do not take the administered HRP under the present conditions. On the other hand, fluorescent granular perithelial (FGP) cells arise from a leptomeningeal tissue (pia mater) and become situated in the perivascular spaces. They are not clearly defined at 5 days, and their uptake capacity for HRP has not yet developed. At 2 weeks, the FGP cells take definite forms with several inclusion bodies, and their uptake capacity for HRP attains a certain degree. Often, they are located at bifurcations of small blood vessels. At 3 months, the FGP cells differentiate completely in appearance, and their pinocytotic capacity reaches a high level. Consequently, the FGP cells belong to a different type of cell from that of ameboid microglia in their developmental sequences and assume a principle role of scavenging waste products in normal cerebral tissue.
Interaction of the peritoneal cavity to intraperitoneal stimulation: A peritoneal model system to monitor cellular and extracellular events in the formation of granulation tissue
Authors: Leak Lee V. 
Published: February 2005

AbstractThe intraperitoneal injection of bacterial toxin and complete Freund's adjuvant in mice produced the classical inflammatory response. However, when allowed to continue, this process led to the formation of granulation tissue of the mesothelial surface. The initial lesion of the reaction was characterized by the deposition of a copious amount of fibrin filaments which were involved in the adhesion and aggregation of peritoneal cells into discrete cellular mounds on the peritoneal mesothelial surface. By 1 week postinjection, fibrin was markedly diminished and appeared as electron‐dense precipitates upon which collagen fibrils were deposited. By 2 weeks, the amount of collagen was greatly increased; and the granular components of fibrin were markedly diminished. Coincident with the deposition of collagen fibrils, there was also a neovascularization of the cellular aggregates. This process occurred when the blood and lymphatic vessels within the submesothelial connective tissue branched and invaded the newly aggregated cellular mounds. By 1 month, the cellular aggregates had taken on the appearance of granulation tissue with foci of closely packed macrophages, fibroblasts, and a network of newly formed blood and lymphatic capillaries. This intraperitoneal stimulation provides an in vivo system in which the various cellular and extracellular events of inflammation leading to the formation of granulation tissue can be monitored.
Distribution of taste and general sensory nerve endings in fungiform papillae of the hamster
Authors: Whitehead Mark C. , Beeman Cynthia S. , Kinsella Brenda A. 
Published: February 2005

AbstractSensory endings of chorda tympani and lingual (trigeminal) nerve fibers were identified by selective denervation and localized within specific regions of fungiform pipillae in the hamster. The chorda tympani was resected from the middle ear and the peripheral fibers were allowed to degenerate for 1, 3, or 8 days prior to perfusion‐fixation and electron‐microscopic examination of the anterior tongue. Taste buds were virtually devoid of intact nerves by 3 days following chorda tympani denervation. Remnants of the fibers were restricted to taste buds. Lingual fibers, on the other hand, persist in normal numbers after chorda tympani resection and populate perigemmal areas of connective tissue and extragemmal areas located apically in the squamous, nontaste epithelium surrounding the taste bud. This study provides evidence of a segregation of chorda tympani fibers in the taste bud and lingual nerve fibers in the apical fungiform papilla. The lingual nerve‐epithelial arrangement and superficial location, near the least cornified area of the tongue, may be well suited for relatively sensitive somatosensation, possibly mechanoreception. Thus, the apical fungiform papilla appears to be a site where both taste and tactile oral stimuli interact with receptors.
Nature and function of endocytosis in Sertoli cells of the rat
Authors: Morales C. , Clermont Y. , Hermo L. 
Published: February 2005

AbstractThe endocytic activity taking place at the apex of Sertoli cells was analyzed by using various tracers to demonstrate fluid‐phase and adsorptive endocytosis. Native ferritin and protein‐gold complexes, used to demonstrate fluid‐phase endocytosis, were internalized by Sertoli cells at all stages of the cycle of the seminiferous epithelium. At 5 min after injection, the tracers were found in the large spherical or C‐shaped vesicles seen in the apical processes; at 15 and 30 min, the tracers accumulated in light multivesicular bodies, and at 60 min in dense multivesicular bodies and lysosomes. At later time intervals, an increasing number of lysosomes contained the tracers. Following injection of cationic ferritin or concanavalin A‐ferritin, these tracers, used to demonstrate adsorptive endocytosis, were found to be found to the plasma membrane of Sertoli‐cell apical processes but were not collected by the large cytoplasmic apical vesicles, multivesicular bodies, or lysosomes. As an exception, a few special multivesicular bodies seen in the large apical processes which encapsulate the heads of late spermatids at stage VII of the cycle contained these tracers. During stage VIII of the cycle, the residual bodies which detach from the mature spermatids are phagocytosed by Sertoli cells. Such residual bodies do not contain their own hydrolytic lysosomal enzymes. However, it was observed that the lysosomes which form as a result of the fluid‐phase endocytic activity of the Sertoli cells fuse with the phagocytosed residual bodies and by means of their hydrolytic enzymes contribute to the rapid disintegration of these bodies. Thus, during stage VIII of the cycle, the Sertoli cells integrate two distinct processes, i.e., fluid‐phase endocytosis and phagocytosis.
Proliferation and differentiation sequence of osteoblast histogenesis under physiological conditions in rat periodontal ligament
Authors: Roberts W. Eugene , Morey Emily R. 
Published: February 2005

AbstractTo define the mechanism of osteoblast histogenesis, nuclear morphometry was utilized as a marker for precursor cell differentiation. One hour after 3H‐thymidine injection, groups of 7‐week‐old rats were killed at hourly intervals over one complete 24‐hr photoperiod (LD 12:12). S‐phase and mitosis were assessed in autoradiographs of 3‐μm sections of molar periodontal ligament (PDL) adjacent to a physiological bone‐forming surface. Labeled nuclei were divided into four categories according to morphometry of nuclear size: A (40–79 μm3), B (80–119 μm3), C (120–169 μm3), and D (≥ 170 μm3) cells. C and D cells synthesize DNA during the light and divide in the following dark phase; the rhythm for A cells is the opposite. B cells demonstrated no preference and were subsequently determined to be nonosteogenic. Compared to A cells the S‐phase photoperiod of C and D cells (combined) is approximately a one‐to‐one reciprocal relationship, suggesting two proliferating progenitors in series. Based on arrest points in the histogenesis sequence, five compartments are defined: (1) A cells, less differentiated, self‐perpetuating precursors; (2) A′ cells, committed osteoprogenitors; (3) C cells, G1 stage preosteoblasts; (4) D cells, G2 stage preosteoblasts; and (5) Ob cells, morphologically distinct osteoblasts. Minimal elapsed time for the A →A′ → C → D → Ob sequence is about 60 hr (five alternating dark/light cycles). A stress/strain‐mediated increase in nuclear volume (A′ → C) is an important, rate‐limiting step in osteoblast differentiation.
The effects of the organophosphate insecticide malathion on very young chick embryos: Malformations detected by histological examination
Authors: Wyttenbach Charles R. , Thompson Sandra Collins 
Published: February 2005

AbstractThis histological study sought to determine the nature and incidence of developmental abnormalities induced by one of the reportedly least teratogenic of insecticides injected into very young chick embryos. Using techniques to assure rapid contact between injectant and embryo, eggs incubated for 24, 48, or 72 hr were injected with corn oil or 125 μg‐4.0 mg malathion. The embryos were recovered 48 hr later, paraffin‐embedded, serially cross‐sectioned, and examined in detail. Structures affected (and the nature of the defects) were as follows: (1) wing level notochord and spinal cord (folded or undulated); (2) trunk/leg level spinal cord (variously, neural folds unfused, roof infolded, canal partitioned, etc.); (3) eye (lens misshapen or severely thinned, optic cup incompletely invaginated); (4) diencephalon (epiphysis bifurcated or off‐center, supernumerary outgrowths); (5) cardiovascular structures (atrium and major blood vessels enlarged); and (6) tailbud (curled into hindgut: ourentery). Overall incidence was both dose‐ and age‐related, doubling for each doubling of dose and tripling for each 24 hr less age at exposure. For most (not all) individual structures, incidence was greatest when exposed at 24 hr and nil at 72 hr. Severity of effect was not consistently doseor age‐dependent. We conclude that (1) contrary to previous reports, 24‐ to 72‐ hr embryos are highly vulnerable to insecticide exposure, with the youngest the most vulnerable, and (2) many of the defects detected may be attributed to either of two mechanisms: failure in formation of the supportive sheath, or factors that cause epithelial morphogenesis (e.g., microtubules, microfilaments, extracellular material, cell‐to‐cell adhesion mechanisms). Previous observations that 1‐ to 3‐day embryos are relatively unresponsive to insecticides are probably artifactual owing to imprecise techniques.
Quantitative genetic variation in the skeleton of the mouse: II. Description of variation within and between inbred strains
Authors: Lovell D. P. , Johnson F. M. , Willis D. B. 
Published: February 2005

AbstractVariation in the skeletons of over 400 male and female mice from 12 genotypes was investigated by using multivariate statistical methods. A series of discriminant functions explains the differences in the shape of six bones: mandible, os coxae, femur, tibia‐fibula, scapula, and humerus. The anatomical features of bone shape described by these functions are summarized together with illustrations of the typical shapes of each bone from the 12 genotypes. Variability within genotypes was investigated by using the Mahalanobis D2 distance—a measure of the difference between two points representing multivariate data—from the group mean. A series of variants were detected ranging from grossly abnormal bones to bones showing subtle differences localized to specific regions. Examples of the variants found are illustrated.
Role of apical tubules in endocytosis in nonciliated cells of the ductuli efferentes of the rat: A kinetic analysis
Authors: Hermo Louis , Spier Nigel , Nadler Norman J. 
Published: February 2005

AbstractThe apical region of nonciliated cells of the ductuli efferentes of the rat contains tubular coated pits (TCP) connected to the apical plasma membrane, apical tubules (AT) which occasionally show a partial coat, and endosomes which are often continuous with one or more apical tubules. To investigate the formation and fate of TCP and AT, a quantitative analysis was performed on the labeling indices of these structures at various time intervals (0.5–120 min) after a single injection of a tracer, cationic ferritin (CF), into the lumen of the rete testis. The labeling indices of both TCP and AT exhibited similar cyclical patterns, first reaching a peak at 25 min, then dropping to a minimum at 35 min, then rising to a second peak at 60 min. Since TCP were well labeled at 30 sec while AT were not, the tracer must rapidly enter TCP and thence AT. However, since tracer was virtually absent from the lumen by 30 min, it was not possible to reconcile the second peak of labeling index of TCP and AT by this mechanism. In another experiment, rats were injected once as before, injected again at 30 min, and then sacrificed at 30 min following the second injection. The results from this experiment showed that the labeling index of TCP and AT did not drop but was similar to that of the 60‐min peak after a single injection. The interpretation is that there was recycling of tracer, which had already migrated from TCP to AT to endosomes, back to the apical plasma membrane via apical tubules. Moreover, when rats were injected once, injected again at 30 min, and sacrificed 3 min following the second injection, the labeling index for TCP and AT was significantly higher (P < .05) than at the 30‐min time interval after a single injection, indicating that recycled apical tubules were functionally capable of binding further CF. Morphological observations on images of transition between TCP and AT and the fact that AT were often found connected to endosomes suggest that TCP detach from the cell surface to give rise to AT, which in turn fuse to form endosomes. The kinetic analysis demonstrates in quantitative terms that a portion of the AT, which fuses to form endosomes, recycles back to the apical plasma membrane and contributes to the formation of new TCP.
Identification of noradrenergic nerve terminals immunoreactive for neuropeptide Y and vasoactive intestinal peptide in the rat kidney
Authors: Knight D. S. , Fabre R. D. , Beal J. A. 
Published: February 2005

AbstractCryostat‐and vibratome‐cut sections of rat kidneys were singly or doubly labeled to visualize immunoreactive tyrosine hydroxylase (THI), dopamine beta‐hydroxylase (DBHI), vasoactive intestinal peptide (VIPI), and neuropeptide Y (NPYI). Rats were perfusion fixed with 2‐4% paraformaldehyde with or without 0.15% picric acid and rinsed in buffer for 18‐48 hr. Single antigens were labeled with horseradish per‐oxidase in vibratome sections, whereas cryostat sections were used to label one antigen with perox‐idase and another with a fluorophore in the same tissue section. A dense plexus of DBHI noradren‐ergic nerves innervates the renal arterial tree, and such nerves innervate the interlobar veins and renal calyx as well. Immunoreactive NPY is colocal‐ized in most of these nerves, but some intrarenal noradrenergic nerves do not contain NPY but do contain VIP immunoreactivity. The distribution of NPYI nerves resembles that of DBHI nerves, whereas most perivascular noradrenergic nerves immunoreactive for VIP innervate selected arcuate and interlobular arteries. A small population of nonadrenergic, VIPI nerves innervates the renal calyx.
Mitochondrial structure revealed by high‐resolution scanning electron microscopy
Authors: Lea Peter J. , Hollenberg Martin J. 
Published: February 2005

AbstractMitochondrial structure has been examined in three dimensions using high‐resolution scanning electron microscopy in cells from rat liver, retina (photoreceptors and retinal pigment epithelium), and kidney (proximal convoluted tubular cells and podocytes). Tissues were prepared by aldehyde‐osmium fixation and freeze cleavage using a cryoprotectant, followed by removal of the cytosol by immersion in a dilute osmium tetroxide solution. The microscope used (Hitachi S‐570) was equipped with a secondary electron detector located in the column above the specimen, situated within the objective lens. Mitochondria in all tissues examined were found to have only tubular cristae, which in some instances could be seen to span the entire diameter of the organelle. The walls of the tubular cristae, when unfractured, were in contact with the inner mito‐chondrial membrane; and their lumens were open to the intermembranous space. We hypothesize that in cells of many, perhaps most tissues, mito‐chondrial cristae are not shelf‐like but are, in fact, tubes which span the mitochondrial matrix and are continuous with the inner mitochondrial membrane at both ends.
Human gallbladder mucosa infrastructure: Evidence of intraepithelial nerve structures
Authors: Gilloteaux Jacques , Pomerants Boris , Kelly Thomas R. 
Published: February 2005

AbstractThe zinc iodide‐osmium tetroxide (ZIO) fixative‐staining method was used along with topographical ultrastructure to investigate cholecystectomized human gallbladders under light and electron microscopic techniques. This method delineated neuronal structures which may be involved in controlling the functions of the gallbladder epithelium. Three epithelial cell types were described in the surface epithelium: (1) Co lumnar clear cells; (2) dark, tuft osmiophilic cells; and (3) basal clear cells with electron‐dense granules and showing intense ZIOphilic staining properties. While mucous granules were delineated in the first two cell types, the columnar epithelial clear cells are of uncertain function(s) and content but are probably absorptive cells. The small basal clear cells displaying intense ZIOphilia are associated with intraepithelial nerve endings. These nerve structures may have a sensory and/or motor function(s); they were detected throughout the gallbladder epithelial lining and mucosa.