bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hormones and the lung. I. Thyroid hormones and glucocorticoids in lung development
Authors: Hitchcock Karen R. 
Published: February 2005

AbstractIt has been proposed that thyroid hormones may have a role in the regulation of lung development and the maturation of the surfactant system. The purpose of this study was to examine the effects of exogenous thyroxine (T4) on rat lung development and to investigate possible interactions of this hormone with the glucocorticoids, other hormones implicated in the regulation of lung development.A number of different experimental protocols were utilized: T4 was administered to day 17 and 18 rat fetuses from untreated animals as well as from animals which had been adrenalectomized or treated with the 11‐β‐hydroxylase inhibitor, Metopirone; replacement hydrocortisone was administered to some groups. Sham‐operated and untreated animals were included as controls. Animals were sacrificed from days 19‐22 (term, day 22‐23) of gestation and the fetal lungs were examined. Accelerated lung development was observed in all experimental groups receiving T4. Alveolar epithelial cells were more differentiated in comparison to controls. Glycogen deposits were diminished, cell flattening was more advanced, mitochondria, Golgi complexes and rough endoplasmic reticulum were more prominent, and lamellar bodies, storage sites for pulmonary surfactant, were greatly increased in number. Secretion of lamellar bodies into the alveolar space was also stimulated. The results also indicated that T4 and glucocorticoids act together in the acceleration of lung development. Under conditions of decreased glucocorticoids (Metopirone treatment and adrenalectomy), stimulatory effects of T4 were still evident but less pronounced; hydrocortisone replacement increased the observed stimulation. Maximal acceleration of lung development was observed subsequent to T4 and uncontrolled surgical stress. These results demonstrate that T4 can accelerate rat lung development and that this acceleration is maximal in the presence of glucocorticoids.
Survey of the morphology of the dog kidney
Authors: Bulger Ruth Ellen , Cronin Robert E. , Dobyan Dennis C. 
Published: February 2005

AbstractDogs are frequent subjects in experimental studies of renal physiology and pathology in spite of the paucity of information on their normal renal morphology. In this study, gross morphology, light microscopy, and scanning and transmission electron microscopy were used to describe dog renal anatomy. The dog has a multilobed kidney with the medulla fused into an elongate crest and a renal pelvis of elaborate shape. The outer zone of the medulla lacks a definitive outer stripe. The proximal tubule consists of four distinct anatomical segments. Dark cells are abundant in the collecting duct of the inner medulla. The majority of the nephron segments demonstrate remarkable similarities to those of the human kidney and less to those of the kidney of the laboratory rat.
Ependymal changes in experimental hydrocephalus
Authors: Page Robert B. , Rosenstein Jeffrey M. , Dovey Barbara J. , Leure‐Dupree Alphonse E. 
Published: February 2005

AbstractA morphologic investigation of ependyma over gray matter (caudate nucleus) and over periventricular white matter (tapetum) of the rabbit lateral ventricle was performed four months after the induction of experimental hydrocephalus. Ependymal cells over the caudate nucleus are not modified by hydrocephalus. They remain cuboidal and heavily ciliated. Numerous microvilli cover the cell surface. The extracellular space of the neuropil is not expanded. Ependymal cells over the periventricular white matter are markedly modified. The characteristic response of these ependymal cells is to enlarge and to form lacunae in their apical cytoplasm. Their apical, horizontal cytoplasmic processes elongate as adjacent ependymal cells separate. The ex‐tracellular space of the neuropil is expanded.It is proposed that the changes seen in ependymal cells over periventricular white matter are a response to enlargement of the ventricular surface permitted by the orientation of neuronal and glial fibers parallel to the ventricular surface. With expansion of the ventricular surface, overlapping apical processes become elongated and modified, containing a terminal web. With further enlargement, sliding of an overlapping apical process of one cell uncovers the apical process of its neighboring cell. By this mechanism, the ventricular surface area of any ependymal cell whose surface has been partially covered by its neighbor is increased. With further progression, this compensation fails and the neuropil is exposed to the ventricular cavity.Over caudate nucleus, expansion of ventricular surface is hindered by the disposition of fascie adherentes along intercellular clefts oriented perpendicular to the ventricular surface. Lateral sliding of horizontal apical processes does not occur as such processes are not found in ependyma over the caudate nucleus.The differential response of the ventricular surface in these two areas characteristically seen in hydrocephalus is; determined by regional differences in the morphology of their ependymal cells and underlying neuropil.
The innervation of the mouse adrenal cortex
Authors: Migally Nabil 
Published: February 2005

AbstractThe fine structure of the mouse adrenal cortex was examined with the electron microscope for the presence of neural elements. Several axon terminals containing mostly clear vesicles (60 nm) were noted in the vicinity (250 nm) of the capsular fibroblasts. In the subcapsular region, myelinated as well as unmyelinated fibers were commonly found. Preterminal and terminal axons were also found in close relationship to the parenchymal cells in the zona glomerulosa. Nerve bundles were the most common neural elements in the zona fasciculata. In the zona reticularis axon terminals containing both clear (60 nm) and dense core (120 nm) vesicles were seen in close proximity (30 nm) to parenchymal cells. Although this study did not delineate the type of fibers involved, the axon terminals resemble those of autonomic nerves.This study demonstrates innervation of the mouse adrenal cortex, thus corroborating similar reports by others in different species.
Fine structural differentiation of germ layers in the mouse at the time of mesoderm formation
Authors: Batten Bruce E. , Haar Jack L. 
Published: February 2005

AbstractThe morphology of early postimplantation mouse egg cylinders was studied using light and electron microscopy. Implantation sites at seven, seven and one‐half and eight days of gestation were dissected from the myometrium and whole implants, including both decidua and egg cylinders were processed for electron microscopy. Pre‐primitive streak egg cylinders were composed of two germ layers, a tall columnar ectoderm and an outer visceral endodermal layer. Ectodermal cells demonstrated large oval nuclei and an organelle sparse cytoplasm except for many free polyribosomes. The visceral endodermal layer was composed of two cell populations. One visceral endodermal cell type observed was tall columnar in shape and appeared absorptive as demonstrated by many microvilli, pinocytotic profiles and lysosomal granules. This population was confined to extraembryonic regions of the egg cylinder. The second visceral endodermal cell type, squamous in shape, evidenced only a few microvilli, pinocytotic profiles and lysosomal granules. This population was confined to the embryonic region of the egg cylinder. Concurrent with the formation of the primitive streak an increased number of cellular junctions and nuclear pores became evident in the ectoderm. Mesodermal cells were large and stellate‐shaped exhibiting many filapodia which made contact with adjacent mesodermal elements. Later the cephalic region of the primitive streak proliferated resulting in the migration of wedge‐shaped mass of cells, the head process. At the most ventral extremity of the post‐primitive streak egg cylinder the cells of the head process became intimately associated with the ectoderm by areas of focal contact and gap junctions.
Morphology of the perforating cartilage canals in the proximal tibial growth plate of the chick
Authors: Hunt Curtiss D. , Ollerich Dwayne A. , Nielsen Forrest H. 
Published: February 2005

AbstractPerforating canals arise exclusively from junctional canals just above the reserve zone and they do not branch after entering the proliferative zone. They are uniformly spaced and arranged in parallel array. The cartilage canals terminate near the beginning of the zone of hypertrophic cartilage cells. Vascular components within the perforating canals consist of a central arteriole surrounded by enlarged, interconnected capillaries which are individually in contact with the adjacent cartilage matrix. TEM shows that the capillary endothelium is extremely attenuated, possesses numerous fenestrations and lacks a continuous basement membrane. The central arteriole is enlarged through the midpart of the canal and then narrows to communicate with the capillaries near the bottom of the canal. The large capillaries ascend from their point of origin and recombine near the top of the growth plate to exit as a single venule. The vascular arrangement therefore describes a system in which the outgoing blood runs in close proximity, but counter to, the incoming blood. This vascular arrangement within the perforating cartilage canal would most likely allow the zone of maturing cartilage cells to receive the highest concentration of nutrients.
Fine structural studies of the rat vas deferens
Authors: Kennedy Samuel W. , Heidger Paul M. 
Published: February 2005

AbstractA fine structural study of the normal rat vas deferens was undertaken utilizing perfusion fixation. Morphological features not previously appreciated were revealed using this technique of fixation, and included the following.The rat vas deferens exhibited a gross morphological and microscopic differentiation along its length: A proximal segment was characterized by a thin muscular wall, an epithelium of low height (comparable to that of the cauda epididymidis) and a distended lumen typically filled with an accumulation of sperm; a distal segment exhibited a thick muscular wall, a convoluted mucosa, and a pseudostratified columnar epithelium with long stereocilia extending into the lumen. The transition from the morphology typical of the proximal segment to that of the distal segment was gradual and progressive, marked by an increase in the mass of the muscular wall and in the height and ultrastructural complexity of the epithelium. Clear or “foamy” cells, characteristic of the cauda epididymidis, were observed in the initial centimeter of the vas deferens. Also, a cell type designated as “mitochondrion‐rich” was observed in the distal vas segment. The structure of the small mitochondria in such cells, however, did not conform to the description of mitochondria in similar cells found in the human (Hoffer, '76). Intraepithelial macrophages containing residual accumulations which often resembled spermatozoan remnants in advanced stages of dissolution were present in all segments of the rat vas deferens, confirming in this species a spermiophagic role for such cells.
Transventricular blood vessels in the third ventricle of the armadillo brain
Authors: Ives Phillip Jay , McArthur Newell H. 
Published: February 2005

AbstractTransventricular filaments were observed with scanning electron microscopy on the dorsolateral wall of the infundibular recess of the third ventricle of the armadillo brain. Two to seven transventricular filaments per animal were present in 6 of 18 animals. There were two types of transventricular filaments, ciliated and bare. Using transmission electron microscopy, we determined that these filaments consisted of a single, central capillary surrounded by ciliated ependymal cells and a small accumulation of axons in five animals. In one animal, a bare filament had a central capillary surrounded by a large accumulation of axons with no surrounding ependyma. The consistent location and structure of these filaments indicate a possible function for a small vascular network, as well as a possible commissural network connecting right and left hypothalami in the region of infundibular nuclei.
Morphology of osteoclasts in resorbing fetal rat bone explants: Effects of PTH and AIF in vitro
Authors: Wezeman Frederick H. , Kuettner Klaus E. , Horton John E. 
Published: February 2005

AbstractOsteoclastic bone resorption was studied using 45Ca‐labeled fetal rat bones cultured in the presence of parathyroid hormone (PTH) and an anti‐invasion factor (AIF) derived from bovine hyaline cartilage which is enriched in a collagenase inhibitor. The specific morphological expressions of osteoclasts cultured in PTH and AIF were observed in both light and electron microscopy and analyzed cytometrically. Stimulation of bone resorption with PTH revealed significant increases in the numbers and activity of osteoclasts, whereas bones cultured in the presence of AIF showed significant decreases in numbers of osteoclasts and altered cell features including the loss of osteoclast contact with bone surfaces. These structural modifications were evaluated with 45Ca release data derived from matched‐pair explants of fetal rat bones, revealing the existence of a relationship between resorptive states of the cultured bones and morphological expressions of osteoclastic activity.
The choroid plexus of the mature and aging rat: The choroidal epithelium
Authors: Peters Alan , Swan Roy C. 
Published: February 2005

AbstractThe choroid plexus of mature and old rats has been examined by both scanning and transmission electron microscopy. It has been shown that the macrophages lying upon the ventricular surface of the choroid plexus have a close association with burr‐like protrusions that extend from the apical surfaces of the choroidal epithelial cells. These protrusions have a dark cytoplasm filled with vesicles and tubules, and projecting from them are thin, shrunken microvilli. It is suggested that these protrusions are phagocytosed by the macrophages and that they are the source of some of the inclusions which become increasingly common within the cytoplasm of macrophages in older rats. The lateral surfaces of the choroidal epithelial cells have also been examined in the scanning electron microscope after exposure of the surfaces by dissection. In such preparations it is apparent that the elaborate interdigitations between adjacent cells are effected by irregular and vertically arranged folds confined to the basal portions of the lateral cell surfaces. Lastly, it has been shown that at the junction between the choroid plexus and the ependyma in the lateral ventricle, there are two modes of transition between the choroidal and ependymal epithelia. In one, typical choroidal and ependymal epithelial cells lie next to each other to produce a distinct and continuous boundary. In the other mode the boundary is also continuous, but there are modified ependymal cells present. These modified cells have short, relatively sparsely distributed microvilli and not more than one or two cilia.
Circulation of cerebrospinal fluid in the bullfrog, Rana catesbiana
Authors: Tornheim Patricia A. , Foltz Floyd M. 
Published: February 2005

AbstractIn order to demonstrate features of the cerebrospinal fluid (CSF) path in the amphibian, 2‐6 m̈l of either Evans Blue‐albumin (EBA) or ferrocyanide were injected into the ventricular system of anesthetized bullfrogs. The animals were sacrificed 1 to 135 minutes after injection by either quick freezing (EBA injections) or fixative perfusion (ferrocyanide injections). The contents of the cranial and vertebral cavities were then examined grossly and histologically for distribution of the tracers. In all animals, the tracers were seen throughout the ventricular cavity and in the subarachnoid space surrounding the caudal hindbrain. The site of communication between these two fluid spaces was the posterior tela of the hindbrain. Within this tela, “pores” were found between groups of pavement‐like ependymal cells. In many animals, tracer was also observed in the vertebral subarachnoid and epidural spaces, adjacent to spinal nerve roots. In three EBA‐injected animals, this tracer was also seen in the subcardinal lymph spaces. These findings suggest that the subarachnoid space in the bullfrog communicates functionally with the ventricular system by way of specialized “pores” in the posterior tela of the hind‐brain. There is also indication of movement of fluid within the subarachnoid space which is predominately caudal in direction, with a primary absorptive path for CSF that consists of a perineural route to the lymphatic system.
Effect of thyroparathyroidectomy (TPX) on the zona reticularis: A quantitative ultrastructural study
Authors: Conran Richard M. , Nickerson Peter A. 
Published: February 2005

AbstractAtrophy of zona reticularis cells was observed two weeks after surgical thyroparathyroidectomy (TPX). Quantitative morphological techniques for electron microscopy showed significant decreases in the volume of cytoplasm, nucleus, mitochondria, smooth endoplasmic reticulum and lipid droplets in the zona reticularis of TPX rats. In addition, many mitochondria contained lipid droplets, some of which occupied virtually the entire matrix of mitochondria. The volume per cell of mitochondria with these inclusions increased significantly after TPX. The lipid droplets may well arise from cytoplasmic droplets by increased transport or reduced metabolism of cholesterol, or by direct incorporation of droplets into the mitochondrial matrix. The serum corticosterone level of TPX rats sacrificed under quiescent conditions did not differ significantly from that of controls. Hypothyroidism induced a significant increase in the volume of peroxisomes per cell in TPX animals which may be related to changes in lipid metabolism or transport.
Role of the left interventricular sulcus in formation of the interventricular septum and crista supraventricularis in normal human cardiogenesis
Authors: Meredith M. Alexander , Hutchins Grover M. , Moore G. William 
Published: February 2005

AbstractSerial sections of normal human embryos were studied and three‐dimensional images reconstructed to determine the early development of the interventricular septum. The position of the interventricular septum is determined in stage 9 of normal development by the formation of the left interventricular sulcus. As a result of unknown properties of the cells of the myocardial layer, the left interventricular sulcus persists while the right disappears, producing the initial lateral asymmetry of the primary heart tube. By stage 14, the left interventricular sulcus forms a spiral which is continuous with the developing interventricular septum. The dorsal limb of the spiral passes to the right between the atrioventricular canal and the origin of the outflow tract, and is lost in the wall of the trabeculated right ventricle. It appears that this dorsal limb of the spiral is the precursor of part of the cirsta supraventricularis. The midportion of the sulcus, the bulboventricular groove, becomes the socalled fibrous continuity between the aortic and mitral valves. The ventral limb of the spiral passes caudally in the anterior interventricular groove and then dorsally and cranially toward the dorsal cushion of the atrioventricular canal. The ventral limb of the spiral is continuous with the crest of the muscular interventricular septum, which develops by apposition of tissue from the expanding right and left ventricles. From stage 14 to stage 19, the muscular interventricular septum, the atrioventricular endocardial cushions, and the ventricular end of the spiral ridges of the outflow tract appose and fuse. Subsequent formation of the membranous interventricular septum completes the physical separation of the right and left ventricles.
Morphological study of the desert heteromyid kidney with emphasis on the genus perognathus
Authors: Altschuler Eric M. , Nagle Ray B. , Braun Eldon J. , Lindstedt Stan L. , Krutzsch Philip H. 
Published: February 2005

AbstractThe renal morphology of three species of desert dwelling Perognathus rodents were compared to Dipodomys and two species of sympatric cricetid rodents. Perognathus has a highly adapted unipolar kidney capable of urine concentration up to 7,500 mOsm/KgH2O. Two major modifications were observed in these kidneys. (1) There is elongation of both the inner and outer medulla. When the thickness of the regions in P. penicillatus are factored by kidney weight it is found that the outer medulla is 3.8 and the inner medulla is 2.2 times greater in length than the extensively studied Dipodomys merriami. (2) There is great variance in glomerular size with approximately 20% of the glomeruli being very large and located in the juxta medullary region. These glomeruli are 1.5‐1.6 times greater in diameter than the more numerous superficial glomeruli. These structural modifications are quantitated and the functional implications are discussed particularly in relation to urine concentrating ability in these desert inhabitants.
Ability of neural crest cells from the embryonic chick to differentiate into cartilage before their migration away from the neural tube
Authors: Hall Brian K. , Tremaine Robert 
Published: February 2005

AbstractWhether neural crest cells from the avian embryo are determined for chondrogenesis before they begin their migration away from the neural tube (i.e., before H. H. stages 8.5‐9) was investigated by establishing neural folds from embryos of H. H. stages 5‐11 either in organ culture, or as grafts to the chorioallantoic membranes of host embryos. Cartilage differentiated from neural folds taken from embryos of H. H. stages 5‐7 but not from those taken from older embryos. This stage specific pattern was reversed when the tissue adjacent to the neural tube was grafted to the chorioallantoic membrane. Cartilage only formed from tissues isolated later than H. H. stage 8; i.e., when these adjacent tissues contain neural crest cells. We concluded that neural crest cells are determined for chondrogenesis while still in the neural tube and before their migration to the face and head. This is in contrast to the situation in the only other group which has been examined, the urodele amphibians.
Phenytoin (dilantin)‐induced cleft lip and palate in a/j mice: A scanning and transmission electron microscopic study
Authors: Sulik K. K. , Johnston M. C. , Ambrose L. J. H. , Dorgan D. 
Published: February 2005

AbstractHigh incidences of cleft lip and palate (CLP) Produced by maternal intraperitoneal administration of 75 mg/kg pehnytoin on gestational day 10 to A/J mice are associated with asevere size reduction in the lateral nasal process. Scanning and transmission EM analyses of this region demonstrate a marked change in the morphology of the mesenchymal cells underlying the surface epithelium in treated versus control day 11 (7‐tail somite) embryos: long, branching cellular processes, which form a dense meshwork that appears to interact with the epithelial basement lamina in control embryos are undeveloped or absent in phenytoin‐treated embryos. The ultrastructural morphology of these cell processes is described and their possible importance in normal development is discussed. Scanning EM observations of incomplete clefts of the lip which frequently result from phenytoin treatment indicate that Simonart's bands form from fusionof the lateral and medial nasal processes in association with a lack of fusion of the maxillary process with the medial nasal process.