bluuebunny/crossref_metadata_2025_split huggingface dataset:
The development of the elastic cartilage of the mouse pinna
Authors: Sanzone Charles F. , Reith Edward J. 
Published: February 2005

AbstractThe development of the elastic cartilage in the mouse pinna was studied with the electron microscope. For descriptive purposes, the developmental process was divided into five stages. These begin with the onset of cartilage matrix production by chondroblasts. The second stage is the major mitotic stage although the cells now resemble chondrocytes and cartilage matrix production evidently continues. This is followed by a period during which cartilage matrix production appears to be the major activity of the chondrocytes. In Stage IV, the cells continue to produce cartilage matrix but at the same time they also produce lipid which comes to occupy most of the cell as a large lipid droplet. In the adult, Stage V, matrix production appears to be at an end and each cell contains a lipid droplet which is so large that the cells bear some resemblance to white fat cells and might be designated as lipochondrocytes.The adult cartilage matrix contains elastic plates in a three‐dimensional honeycomb pattern. Between the elastic plates and the cells, the matrix contains elements similar to those seen in hyaline cartilage but it does not contain matrix vesicles such as those which have been associated with the calcification of cartilage.Two types of filaments differing in appearance, size, and location are seen within the chondrocytes. They have been designated cytofilaments and cortical filaments. Cytofilaments are dispersed throughout the cell and also contact the substance of the lipid droplet, cortical filaments (sub‐plasmalemmal microfilaments) are located directly under the plasma membrane. They are thought to be involved in movement of the plasma membrane as a concomitant to extracellular fibrogenesis.
Topographical changes along the neural fold associated with neurulation in the hamster and mouse
Authors: Waterman Robert Earle 
Published: February 2005

AbstractThe topography of the ectoderm was examined by scanning electron microscopy during neurulation in hamster and mouse embryos. Stages from the appearance of the neural folds to closure of the posterior neuropore were studied. Progressive development of a zone of altered cellular morphology was observed along the crests of the neural folds. This zone evolved from and abrupt transition between surface and neural regions of the ectoderm to a narrow band of flattened cells which exhibited numerous membranous “ruffles” in the mouse, or blebs and presumably degenerating cells in the hamster, immediately prior to contact between the folds. These alterations were more prominent along the anterior than the posterior portions of the folds. Contact of the folds occurred first between the flattened cells with subsequent union of the surface cells. Stages of neural crest cell formation were observed subjacent to the zone of alterations in histological sections. It is suggested that the observed surface alterations may reflect changes in the membrane properties of the altered cells which are correlated with both neural crest formation and initial adhesion between the folds.
Scanning microscopy of pituitary vascular casts
Authors: Page Robert B. , Munger Bryce L. , Bergland Richard M. 
Published: February 2005

AbstractVascular casts of the pituitary‐median eminence complex from seventeen adult female rabbits were examined with the scanning electron microscope. The results of this study confirm the presence of a single capillary bed common to the entire neurohypophysis. Arterial supply to the rabbit pituitary is only to the neurohypophysis. A direct supply to adenohypophysis was not found.Within the median eminence there are an external and internal capillary plexus. The internal capillary plexus is directed toward the infundibular recess of the third ventricle. It does not receive a direct arterial supply but derives its blood supply from the external plexus before draining to the adenohypophysis.Vessels of the posterior median eminence are confluent with vessels of the infundibular stem.On the basis of these studies, it is proposed that the entire neurohypophysis, not simply the median eminence, serves as the final common pathway to the glandular pituitary. It is also proposed that in the median eminence, vessels are organized to deliver blood containing hypothalamic releasing and inhibiting hormones as well as posterior lobe neural hormones (antidiuretic hormone and oxytocin) to the ventricular surface for subsequent transport to cerebrospinal fluid and distribution to the brain.
Age‐related changes in the intact and sympathetically denervated gerbil pineal gland
Authors: Reiter Russel J. , Welsh Marcia G. , Vaughan Mary K. 
Published: February 2005

AbstractThe pineal gland of four‐month‐old gerbils contains numerous calcareous deposits (corpora arenacea or concretions). Also, the tissue appears vacuolated due to the presence of a number of large rounded spaces. The deposits are usually associated with or lying within these “vacuoles”. By eight months of age, the number of both the corpora arenacea and the “vacuoles” are increased over those present in the pineals of four‐month‐old gerbils. Bilateral superior cervical ganglionectomy at one month of age prevents the formation of both the concretions and “vacuoles”. The cells in the sympathetically denervated pineal glands are smaller than those in pineal glands of animals that possess intact superior cervical ganglia.
Functional anatomy of the hands of fur seals and sea lions
Authors: English Arthur Wm. 
Published: February 2005

AbstractDissections and manipulations of the hands of 14 specimens of four genera of fur seals and sea lions and of generalized fissiped carnivores were used to identify the structural modifications involved in formation of the expanded forelimb paddles characteristic of these pinnipeds. These morphological peculiarities were then correlated with differences in locomotor function, both on land and in the water, on the basis of previously published data, for the purpose of identifying modifications of structure and function which have adaptive value. Structural differences found in the manus of fur seals and sea lions include: (1) reduction in size of the ulnar side of the carpus and a radial shift in the length‐order of the digits, (2) development of musculature in the antebrachial fascia which attaches to the caudal margin of the flipper, (3) orientation of the radial side of the manus dorsal and radial to the rest of the hand, (4) increased range of possible midcarpal movement and in deviational mobility at the first and fifth digits, (5) attachment of forearm musculature onto radial digits and (6) well‐developed hypothenar muscles and absence of thenar muscles. Modifications in hand structure are viewed as providing a morphological basis for employment of the hand to advantage during aquatic locomotion while maintaining thrust‐producing and potentially energy‐conserving capacities during movement on land. As such these differences in structure and function are viewed as adaptations to locomotion in the water and on land which are extensions of locomotor adaptations attributed to modifications of forelimb structure and function associated with the generation of massive aquatic locomotor thrust. The adaptive value of such modifications is interpreted as allowing fur seals and sea lions to swim with speed and thereby capture elusive fast‐swimming prey while maintaining a level of terrestrial locomotor ability compatible with their amphibious mode of life.
The effects of 5‐bromodeoxyuridine and isoproterenol on the postnatal differentiation of rat submandibular gland
Authors: Fukushima Masahiro , Barka Tibor 
Published: February 2005

AbstractThe effects of 5‐bromodeoxyuridine (BrdU) on the postnatal differentiation of rat submandibular gland and on the isoproterenol‐induced changes of differentiation were studied. The rats were injected with BrdU for three consecutive days, beginning at two days of age. The total dose of BrdU was 0.9 mg/g body weight. BrdU caused a severe retardation of growth up to 15 days of age. A rapid growth of the animals between 15 and 22 days indicated a recovery from the effect of BrdU. The growth of the submandibular gland was retarded similarly with a corresponding decrease in DNA, RNA and protein content. Incorporation of tritiated thymidine into the submandibular gland was not altered in the BrdU‐treated animals at one and three days after the last injection of the analog. At days 15 and 22 the rate of thymidine incorporation was greater in the submandibular gland of BrdU‐treated rats as compared to littermate controls. Isoproterenol stimulated thymidine incorporation into the submandibular glands of two‐week‐old rats. This stimulation was not observed in rats which received BrdU at age 7–9 days, prior to the administration of isoproterenol.Electron microscopic observations, including a quantitative analysis of the frequency distribution of the various cell types in the terminal tubules and developing acini, indicated a retardation of acinar cell differentiation in the glands of BrdU‐treated rats. In addition, there was an increase in the number and size of the secretory granules in the terminal tubule cells. BrdU treatment, however, caused no obvious pathologic alterations in the submandibular gland. Administration of isoproterenol for five days, beginning at five days of age, caused an apparent acceleration of the differentiation of acinar cells. In the glands of isoproterenol‐treated rats the acinar cells were enlarged and were filled with homogenous secretory granules. Pretreatment with BrdU partially inhibited the effects of isoproterenol on differentiation and hypertrophy of the submandibular gland. With the given dose of BrdU, approximately 5% of thymine was replaced by bromouracil in the DNA of the submandibular gland. Such a replacement would be consistent with a direct effect of BrdU on the cytodifferentiation in the submandibular gland. However, because of the severe retardation of growth of the BrdU‐treated rats, indirect effects can not be excluded.
Secretion by parafollicular cells beginning at birth: Ultrastructural evidence from developing canine thyroid
Authors: Nunez Eladio A. , Gershon Michael D. 
Published: February 2005

AbstractThe ultrastructure of developing canine parafollicular cells has been examined. The hypothesis that secretion is relatively inactive prior to birth but very active at and following birth was tested. Parafollicular cells develop and accumulate characteristic secretory granules prior to birth. However, there is little or no evidence of exocytosis at this time. At birth and during the neonatal period, but not in adult thyroids, sings of exocytosis of granular contents by parafollicular cells are abdundant. Just prior to the expected date of birth and before evidence of exocytosis appears, parafollicular cells accumulate intracisternal granules within rough endoplasmic reticulum. These observations are consistent with the view that parafollicular cells first become actively secretory around the time of birth and are more active at this time than in early fetal or later adult life.
Effect of puromycin on the ultrastructure of keratohyalin granules
Authors: Singh Baldev B. , McKinney Ralph V. , Brewer Phyllis 
Published: February 2005

AbstractKeratohyalin granules (KHG) from control and puromycintreated hamster cheek pouch epithelium were studied by electron microscopy. The animals were killed 1–4 hours after injection with 75–100 microgram puromycin per gram body weight; controls were injected with saline. The KHG from control animals were round or oval and consisted of a finely granular background matrix containing many small, round, homogeneous electron‐dense deposits. The KHG from puromycin‐treated animals showed marked variation in morphology and size. They consisted of a coarse granular or speckled matrix and round, club‐shaped or comma‐shaped electrondense deposits. Since puromycin is known to inhibit protein synthesis, alterations in KHG structure support previous reports suggesting the protein nature of KHG.
Light and electron microscopic localization of ATPase in normal and degenerating testes of syrian hamsters
Authors: Gravis Curtis J. , Yates Robert D. , Chen I‐Li 
Published: February 2005

AbstractThe distribution of Mg++‐activated ATPase was determined with light and electron microscopy in normal and degenerating seminiferous tubules. In the normal animals ATPase was localized in the interface between spermatids and Sertoli cells, in association with the cytoplasmic filaments contained within Sertoli cell processes, and in the lymphatic endothelium. ATPase activity increased in degenerating tubules as observed by light microscopy. Electron microscopic investigations of the degenerating tubules which contained only spermatogonia and Sertoli cells revealed reaction product on the outer surface of the Sertoli cell processes and within the interface between adjacent Sertoli cells. Reaction product was also observed in the Sertoli cell processes between the cytoplasmic filaments and the cell membrane. Where filaments were absent in Sertoli cell processes, no reaction product was observed. These electron microscopic studies indicate that the increase in ATPase activity in testicular degeneration is probably a relative increase due to a loss of the germinal elements of the tubular epithelium and subsequent apposition of the Sertoli cell processes. We speculate that the ATPase activity localized within the Sertoli cell processes may be involved in providing an energy source for filament motility.
Polysaccharides in lung alveoli
Authors: Nir Izhak , Pease Daniel C. 
Published: February 2005

AbstractRat lung alveolar surfaces and contents were studied after using concanavalin A as a bifunctional agent to link exposed sugars to horseradish peroxidase, in accordance with a technique developed by Bernhard and Avrameas (1971). The Graham and Karnovsky (1969) diaminobenzidine procedure then was used to provide an electron‐dense reaction product so as to define the distribution of complex carbohydrates in alveoli.A layer of very dense reaction product was intimately associated with the outer leaflets of the luminal plasma membranes of type I and II pneumocytes. Masses of generally less dense reaction product extended irregularly into the alveolar lumens. All pleomorphic membranous material free in the lumens also was coated by reaction product. When highly ordered tubular myelin bodies were seen, the reaction product filled all of the “gutters” created by the intersections of the membranes. Reasons are presented for believing that the intrinsic periodicity of the tubular myelin may be created and maintained by the domains of the complex carbohydrate units demonstrated by this cytochemical technique. The distribution of autologous albumin, demonstrated by antibody staining by Bignon et al. (1975), apparently coincides with the carbohydrate pattern, suggesting both may be associated as a glycoprotein. The ultimate relationships between carbohydrate moieties and phospholipid membrane systems proved to be of such complexity that we believe it justifiable to think that they also may be truly complexed together.
The features of sperm maturation in the epididymis of a marsupial, the brushtailed possum Trichosurus vulpecula
Authors: Temple‐Smith P. D. , Bedford J. M. 
Published: February 2005

AbstractPossum spermatozoa undergo a distinctive process of maturation in the epididymis, as shown by change in the properties of the sperm surface, by modification of their morphology and by their increasing capacity for progressive motility.Modification of the sperm surface over the head and tail is demonstrated by the different affinities of sperm from successive regions of the epididymis for FITC‐conjugated wheat germ agglutinin and concanavalin A, and for cationic ferric oxide colloidal particles. Changes in sperm head morphology are caused by (1) a dramatic reshaping and consolidation of the acrosome in which excess plasma membrane overlying it is sloughed as a cluster of vesicles, (2) a reorientation of the nucleus almost parallel to the axis of the tail and (3) distal movement of the droplet from its initial envelopment of the nucleus to an eccentric position on the anterior segment of the midpiece.Spermatozoa released from the testis and caput epididymidis are essentially immotile or exhibit only lazy uncoordinated movements, whereas many from the corpus and most from the more distal regions of the epididymis display an energetic, progressive motility imparted by a rapid and stiff tail beat of narrow arc. This maturation of the capacity for motility is accompanied by an enhanced stability of the dense fibers and sheath, which become more resistant to the disruptive action of SDS and DTT, and by changes in the ultrastructure of the sperm tail. These include modification of the matrix of the mitochondria and also an unusual differentiation of the midpiece into two distinct segments. The anterior segment is defined by profuse peri‐mitochondrial stacks of membranes which develop as spermatozoa pass through the epididymis. These membranes, although prominent in mature spermatozoa fixed in situ, appear sparse and disorganised in spermatozoa fixed after 15 to 30 minutes of active motility in physiological medium, suggesting their possible utilisation in motile spermatozoa. The posterior segment is characterised by a thick peri‐mitochondrial cytoplasmic sleeve, by spirally arranged parallel fibrous bands immediately beneath the plasma membrane and, subsequently, as spermatozoa pass into the lower corpus epididymidis, by rows of flask‐shaped surface invaginations which develop between the spiral bands.Despite broad similarities in the features of sperm maturation in this marsupial and in eutherian mammals, there are distinct differences in the structural organisation of their spermatozoa, particularly in the sperm head. Until more is known of the details of fertilisation in marsupials the significance of these differences will remain unclear.
Monoamine distribution in primate brain. III. Catecholamine‐containing varicosities in the hypothalamus of Macaca mulatta
Authors: Hoffman Gloria E. , Felten David L. , Sladek John R. 
Published: February 2005

AbstractThe histochemical fluorescence technique of Falck and Hillarp was used to examine the distribution of catecholamine‐containing varicosities within the hypothalamus of the rhesus monkey (Macaca mulatta). Varicosities were seen in heaviest concentrations within the periventricular area and the following nuclei: lateral and medial preoptic, supraoptic, paraventricular, arcuate and dorsomedial. Patterns observed presented striking similarities and dissimilarities to catecholamine distribution reported in the rat and cat. Catecholaminergic perikarya were not observed routinely.
Structural development of endocardial cushions
Authors: Markwald Roger R. , Fitzharris Timothy P. , Manasek Francis J. 
Published: February 2005

AbstractDevelopment of chick and rat endocardial cushions (cardiac mesenchyme) was studied histologically (using Nomarski differential interference optics on living and unfixed tissue), ultrastructurally (scanning and transmission electron microscopy), cytochemically (using acidified dialyzed iron as a visual probe for polyanionic material) and autoradiographically (using 35S) to elucidate the origin of the mesenchyme, the morphologic sequences leading to cushion formation and secretion of sulfated glycosaminoglycans, if any, by migrating mesenchymal cells. Cushion formation was similar for both species. Mesenchymal cells appeared initially, in 16‐ to 18‐somite embryos, beneath the endothelium (which lacked a basal lamina) of the future atrioventricular canal and outflow tract. The cytoplasm of cushion mesenchymal cells was structurally similar to the endothelium; probably these cells arose by proliferation of the endothelium. Mitotic figures among the “seeded” cells were also numerous. Cushion cells were initially attached to the endothelium by desmosomes but acquired motile apparatus (pseudopodia and filopodia containing microtubules and microfilamentous bundles). Serial sectioning of successively‐aged embryos (20–44 somites) indicated a centrifugal migratory direction. Interaction of the cell processes with extracellular matrix suggested that the latter was used as a migratory substrate. Contact of the advancing wedge of cushion cells with the myocardium produced no alteration in cell structure or mitotic activity. Localization of hyaluronidase‐sensitive, dialyzed iron (DI) precipitates in 250‐nm Golgi vacuoles and hyaluronidase‐sensitive 35S‐engendered silver grains over cushion cells indicated that this tissue contributed sulfated macromolecules to the matrix. Localization of hyaluronidase‐labile, DI material in coated, endocytic like vesicles and caveolae also suggested potential modification or conditioning of the matrix by migrating mesenchymal cells. Altogether the study established loci in developing cushions where disruption of the developmental sequence could engender valvular or septal defects.
Fixative tonicity for scannig electron microscopy of delicate chick embryos
Authors: Litke Larry L. , Low Frank N. 
Published: February 2005

AbstractFresh pullet eggs (White Leghorn strain) were incubated from 19–26 hours. Blastoderms were fixed in ovo by selected fixatives of various tonicities, postfixed in 2% OsO4, dehydrated in acetone, critical‐point‐dried in liquid CO2, coated with palladium‐gold and observed in a Cambridge S4 scanning electron microscope.Shrunken cells with intracellular yolk granules embossed on the surface are produced by the strongly hypertonic Karnovsky's fixer (Final: 2010 mOsm). Embryos fixed with modified Karnovsky's fixer (Final: 373 mOsm) possess surfaces with irregular microappendages. Swollen cells with few microappendages are obsrved when embryos are fixed in a hypotonic environment (Final: 250 mOsm or less). Ideal fixatives preserve a relatively flat surface, with cells bordered by smooth surface microappendages. For adequate SEM fixation, fixative vehicle should be approximately isotanic for tissue, with aldehyde (2% or less) added to vehicle.
Immunohistochemical localization of gonadotropin‐releasing hormone (GnRH) in the fetal and early postnatal mouse brain
Authors: Gross Douglas S. , Baker Burton L. 
Published: February 2005

AbstractThe objectives were to (a) determine the age in development when GnRH is first detectable in the brain and (b) observe the distribution of GnRH throughout the fetal and early postnatal period. GnRH was localized immunohistochemically in fetal (15, 16, 17 and 19 days of gestation) and early postnatal (1‐ and 7‐day‐old) mice with the peroxidase‐antiperoxidase (PAP) method of Sternberger.In the organum vasculosum of the lamina terminalis (OVLT) and in the median eminence of the fetus, GnRH was first detected at 17 days of gestation. In the OVLT, GnRH was found ventral to the preoptic recess of the third ventricle near the ventral surface of the brain. In addition, GnRH was located adjacent to the superficial portal capillaries near the surface of the median eminence. At 19 days of gestation, the distribution of GnRH was similar to that observed at 17 days and there was a marked increase in amount.In the newborn mouse, GnRH was undetectable in the OVLT and its content in the median eminence was decreased as compared to that observed in the fetus. By the seventh postnatal day, a considerable accumulation of GnRH had occurred in the OVLT and median eminence. In the OVLT, it was associated with capillaries ventral to the preoptic recess, and its distribution in the median eminence was similar to that in the adult mouse.In both the OVLT and median eminence of the fetal and early postnatal mouse GnRH appeared to be stored in axons and axon endings, but was not detectable in nerve cell bodies or ependymal cells. These observations suggest that the potential for neuroendocrine control of gonadotropin secretion exists in the fetal mouse as early as 17 days of gestation.