bluuebunny/crossref_metadata_2025_split huggingface dataset:
The fate of fragments of liver implanted in ectopic sites
Authors: Tavassoli Mehdi , Crosby William H. 
Published: February 2005

AbstractImplanted fragments of liver in ectopic sites do not survive. The failure of survival is associated with lack of vascularization. This results in necrosis of coagulative type which later is replaced by connective tissue. An invasion of polymorphonuclear leukocytes can enhance the rate of this process. Regenerative stimuli such as partial hepatectomy do not change this sequence of events. The lack of vascularization of implants may be due to failure of eliciting an invasive vascular phenomenon which is seen in the implanted fragments of those tissues that survive in ectopic sites.
Effect of fibrillar structure of pericanalicular and intercanalicular bone on X‐ray absorption
Authors: Vose George P. , Baylink David J. 
Published: February 2005

AbstractThe apparent hypermineralization which is often seen adjacent to canaliculi (∼ 2000 Å) and dentinal tubules in microradiographs may be the result of a reversal in orientation of microcanaliculi (∼ 500 Å) and adjacent mineralized fibrils at these sites. Microcanaliculi and adjacent mineralized fibrils, as seen by electron microscopic surface replication, extended at right angles from canaliculi for a distance of about 1–2 μ. In contrast, beyond this zone microcanaliculi were also observed but were oriented at right angles to the microcanalculi that were closer to the canaliculi. Although the significance of the difference in orientation of microcanaliculi in pericanalicular as compared with intercanalicular regions is not known, we demonstrated that when a porous material is x‐rayed parallel to and then at right angles to the longitudinal axis of the porous phase an apparent difference in density is observed. These findings suggest that the apparent hypermineralization of bone adjacent to canaliculi described in former investigations utilizing microradiography may be the result of a difference in orientation of microcanaliculi and adjacent mineralized fibrils rather than a true variation in mineral density.
Ultrastructural changes in articular chondrocytes of mice fed a lard‐enriched diet
Authors: Silberberg Ruth , Aufdermaur Max , Hasler Mary 
Published: February 2005

AbstractWeanling male mice of strain C57B1. were fed a lard‐enriched diet for periods of 1, 4, 7, 10, 14, or 28 days. Beginning during the second week of consumption of this ration, articular chondrocytes of the femoral heads were increased in number and size and showed ultrastructural changes. The latter manifested themselves in nuclear enlargement, intensification of organellar development and in acceleration of regression. There was no evidence of abnormal deposition of lipid material within the chondrocytes beyond that due to organellar disintegration. It was concluded that the early effects of a lard‐enriched diet on articular cartilage consist of an overall stimulation of cell function followed by premature exhaustion. The primary site of action of the dietary fat remains unknown.
In vitro differentiation of tooth rudiments of embryonic mice. II. Growth of isolated thirds of embryonic mouse incisors
Authors: Koch William E. , Koch Barbara A. , Ledbury Priscilla A. 
Published: February 2005

AbstractThe mandibular incisor of the 16 day embryonic mouse was divided into three visibly equal thirds; each third was explanted in vitro to test its capabilities for independent development. Ameloblasts and odontoblasts, present in the distal third at the time of isolation, fail to continue their differentiation. This third flattens, and the tissues become disorganized. Grouping several distal thirds in a single culture did not promote tissue differentiation. The embryonic proximal third remains cohesive The tissues differentiate; both ameloblasts and odontoblasts deposit extracellular matrix. Approximately half of the cultures of the intermediate third show differentiated odontoblasts and extracellular matrix after 11 culture days. Measurements of the volume changes of ameloblasts, odontoblasts, and general mesenchyme were taken over the first six culture days for each third of the rudiment. The volume changes recorded, and the counts of mitotic figures reflect the developmental behavior of each fraction of the rudiment.
Special structural features of the rat portal vein
Authors: Ts'ao Chung‐Hsin , Glagov Seymour , Kelsey Billy F. 
Published: February 2005

AbstractUnlike other rat veins of comparable diameter, the smooth muscle cells of the extrahepatic segment of the portal vein are arranged in two distinct mutually perpendicular layers. The relatively narrow inner layer is nearly circumferential and devoid of vasa vasorum; the cells resemble those seen in other veins. In the longitudinal outer layer, vasa are abundant and the cells contain unusual numbers of mitochondria and abundant pinocytotic vesicles, indicating relatively increased metabolic activity. Between the layers, the connective tissue contains nerve fibers, suggesting coordinated reflex activity.
Hypothalamic‐hypophysial adrenal and thyroid systems: Observations in fetal rats subjected to hypothalamic destruction, brain compression and hypervitaminosis A
Authors: Fujita Tsuneo , Eguchi Yasunobu , Morikawa Yoshio , Hashimoto Yoshiyuki 
Published: February 2005

AbstractRegulation by fetal hypothalamus of adrenocorticotrophic and thyrotrophic function of the fetal anterior hypophysis in the rat was studied by: (1) destruction of the fetal hypothalamic area with an electrocoagulator, (2) compression of the fetal brain by injected paraffin into the fetal skull and (3) induction of fetal exencephaly by hypervitaminosis A in the mother.The body weight of fetuses in which the hypothalamus was damaged was significantly less than that of littermate controls. Volume of the anterior hypophysis was small in fetuses injected with paraffin. The anterior hypophyses were present in all exencephalies, and showed abnormal forms but no reduction in volume. The adrenals were very small in all fetuses in which the hypothalamus was damaged, accompanied by conspicuous shrinkage of cortical cells, while the thyroids were not changed in volume. The height of the follicular cells decreased slightly.The observations suggest that in the late period of fetal life in rats, the hypophysial‐adrenal system is regulated largely by the hypothalamus, but that the hypophysial‐thyroid system is not fully under the control of the hypothalamus.
Intercellular bridges between germ cells in the developing ovary of the tadpole, Rana pipiens
Authors: Ruby John R. , Dyer Robert F. , Skalko Richard G. , Volpe E. Peter 
Published: February 2005

AbstractOvaries obtained from the tadpole, Rana pipiens, and examined with the electron microscope revealed that many of the developing germ cells were joined together by intercellular bridges. All connections exhibited electron‐dense material on the inner surface of the plasma membrane, thus demonstrating the same basic structure as intercellular bridges described in other species. However, the presence of a sleeve‐like subsurface cistern beneath the dense border in the tadpole produces a morphologically more complex connection. A variety of cytoplasmic organelles, including mitochondria and elements of the endoplasmic reticulum, were seen within the confines of these bridges. Possible functions of intercellular bridges are discussed and it is suggested that certain developing germ cells function as nurse cells like those described in some invertebrates.
The reproductive organs of the male spotted skunk (Spilogale putorius)
Authors: Mead Rodney A. 
Published: February 2005

AbstractA relatively well developed prostrate is the only accessory sex gland present in the spotted skunk (Spilogale putorius). The distal end of the vas deferens is quite glandular, but there is no distinct ampullary swelling. The gross morphology of this species is compared with that of several other members of the family Mustelidae.
The carotid body of the weddell seal (Leptonychotes weddelli)
Authors: Morita Ernesto , Chiocchio Sara R. , Tramezzani Juan H. 
Published: February 2005

AbstractLight and electron microscopy of the carotid body of the Weddell seal shows two types of cells, the main and the sustentacular cells.The main cells contain dense osmiophilic granules in variable amount. Their cytoplasma shows either a high or a low electron density. On this basis light and dark main cells were distinguished.The differences in cytoplasm electron density and the great variability in the number of granules were interpreted as expressions of different stages in a process of secretory nature.A very rich innervation with outstanding nerve endings was observed in the carotid body of the Weddell seal. This picture is similar to that observed in stimulated carotid bodies. The carotid body of the Weddell seal a marine mammal that stays underwater for a long stretch of time, may be considered as subjected to frequent stimulations.
Brunner's glands of the echidna
Authors: Krause William J. 
Published: February 2005

AbstractBrunner's glands of the echidna form a thick, interwoven collar confined to the submucosa of the most distal portion of the stomach. The glandular mass ends immediately proximal to the pyloroduodenal junction and empties onto a surface lined by stratified squamous epithelium. Histochemical studies indicate that the secretion elaborated by the glands is an acid mucopolysaccharide.Secretory tubules in the glands consist of large, pyramidal‐shaped cells resting on a delicate basal lamina. They contain large, pale or granular secretory droplets which are membrane bounded and are found in close association with extensive Golgi complexes and also at the apex of the cells. Secretary granules, occasionally fused into irregularly‐shaped complexes in the apical region, appear to rupture the cell membrane and discharge their contents into the adjacent lumen. Small, dense granules are also present but less abundant. The granular endoplasmic reticulum is confined mainly to the perinuclear region and comprises dilated cisternae containing amorphous material. Several small vesicles apparently formed from smooth membrane areas of the ergastoplasm are seen adjacent to the Golgi networks.The epithelium lining the duct is devoid of large secretory granules and contains relatively few organelles.
Shapes and sizes of synaptic vesicles in the cerebellum of the Syrian hamster‐cortex and deep nuclei
Authors: Duncan Donald , Morales Ricardo , Benignus V. A. 
Published: February 2005

AbstractMaterial was obtained from eight adult apparently healthy Syrian hamsters perfused with 3.2% glutaraldehyde in phosphate buffer. Cortex and deep nuclei were prepared for electron microscopy by osmication and Epon embedding. Measurement of size and shape of vesicles was from printx × 50,000. Vesicle profiles whose least diameter was 75% or more of the maximum diameter were classified as round (spherical). If the greatest dimension was more than twice the least, the vesicle was termed flattened, all others oval. So defined, the synaptic sacs in the deep nuclei, large sacs of the granular layer and small sacs of the molecular layer contained more round vesicles than oval and flat combined and differences between these three locations were slight. In large sacs of the molecular layer, oval and flattened vesicles slightly outnumbered round ones. Average sizes were deep nuclei 468 Å, large sacs of granular layer 494 Å, small sacs of molecular layer 452 Å and large sacs of molecular layer 414 Å. Statistical analysis indicated that the mean size of vesicles was significantly different when each of the four locations was compared with the others. These differences are too small to be apparent by inspection. Since the vesicles in the deep nuclei are intermediate in size between those in mossy terminals and the axospinous ones of the molecular layer it was concluded that size and shape of vesicles did not distinguish between excitatory and inhibitory synapses in Syrian hamster cerebellum.
The fine structure of the arteriovenous anastomosis and its nerve supply in the human nasal respiratory mucosa
Authors: Cauna Nikolajs 
Published: February 2005

AbstractThe fine structure of the arteriovenous anastomosis was investigated in the normal human nasal mucosa. The tissues were fixed in 2% osmic acid solution, embedded in Epon and stained with uranyl acetate and lead citrate solutions.It was found that the endothelial basement membrane of the arterial segment of the anastomosis was discontinuous. The anastomosing artery possessed subendothelial cushions of longitudinal smooth musculature which expanded into a thick uniform layer before the artery joined the vein. The fine morphology of these muscle cells did not show epitheloid modification. An elastic membrane of a peculiar structure separated the subendothelial musculature from that of the tunica media. The membrane was continuous with the internal elastic membrane of the proximal artery and with the adventitial elastic mesh of the vein. The anastomosis was supplied by a non‐myelinated periarterial nerve plexus which contained cholinergic and adrenergic axons characterized by agranular and fine granular vesicles respectively. The wall of the vein was devoid of musculature and nerves. It mainly consisted of elastic meshes interspersed with bundles of collagen fibers and occasional fibrocytes.It was suggested that the musculature of the tunica media of the artery was controlled by the cholinergic and adrenergic nerves of the autonomic system, and by the sensory nerves in the form of axons reflexes. The subendothelial musculature was controlled by agents carried in blood and was not influenced by the adventitial nerves.
An electron microscopic study of mesenchyme during development of interdigital spaces in man
Authors: Kelley Robert O. 
Published: February 2005

AbstractCell movements and degenerations occur normally during embryogenesis and have received particular attention during development of limbs in the chick. The present investigation suggests that similar phenomena occur during formation of interdigital spaces in man. Upper limb buds were dissected from a human embryo (CR 15.5 mm, age estimated at 6 weeks postfertilization), fixed in phosphate buffered glutaraldehyde, and prepared for electron microscopy. Mesenchymal cells in developing interdigital zones appeared to be undergoing either mitosis or necrosis. Macrophagy of necrotic mesenchymal cells, which begins distad in the appendage bud, contributes to the final formation of an interdigital space.
Pineral structure and composition in the orangutan (Pongo pygmaeus)
Authors: Quay W. B. 
Published: February 2005

AbstractMicroscopic structure and histochemistry were studied in the pineal organ of a male orangutan (34 kg body weight, 7 years radiological age). Although small in size (1.7 mm long by 1.1 mm wide dorsoventrally) the pineal of this species appears active and has a number of distinctive characteristics: broad exposure on the third ventricle at the pineal recess; permeation by recesses and channels from the dorsal sac; extensive penetration by loops of myelinated fibers from the habenular and posterior commissures; lack of intrapineal nerve cell bodies; presence of different parenchymal cell types having granular and vacuolated cytoplasm; and a densely cellular stroma containing melanin.
Extracellular specializations associated with hemidesmosomes in the fetal rat urogenital sinus
Authors: Flickinger Charles J. 
Published: February 2005

AbstractSpecializations of extracellular structures opposite hemidesmosomes at the basal surface of epithelial cells of the fetal rat urogenital sinus are described. A moderately dense band or lamella ∼ 100 Å wide forms a cap about 50 Å from the plasma membrane. The normally electron‐lucent inner zone between the plasma membrane and the basal lamina is increased in density and may be traversed by filaments or strands of material extending from the cell surface. The basal lamina is thickened and its density is increased locally opposite hemidesmosomes. The possible role of these specializations in adhesion between epithelial cells and the underlying extra‐cellular structures is considered.
Aortic arches in the chick embryo: Origin of the cells as determined by radioautographic mapping
Authors: Rosenquist Glenn C. 
Published: February 2005

AbstractThe origin of the cells which form the aortic arches in the chick embryo was determined by tracing the movements of tritiated thymidine‐labeled grafts excised from medium streak (MS) to head process (HP) stage embryos and transplanted to the epiblast, streak and endoderm‐mesoderm layers of similarly staged recipient embryos.Between the MS and HP stages, the preaortic arch cells migrate in epiblast to the primitive streak, invaginate, and move anteriorly and laterally from the streak into mesoderm; at the HP stage they are lateral to the cells which will form the anterior parts of the dorsal aortae, and medial to the heart‐forming regions. The most anterior prearch cells form the first arch and the more posterior cells form the more posterior arches. The prearch cells are closely associated during migration with the endoderm cells which will form the adjacent branchial arches and clefts.Cells which will form the posterior end of the aorta are still in the epiblast layer at the late medium streak (LMS) stage, but have moved to the primitive streak at the HP stage; they migrate from the streak into mesoderm posterior and medial to the mesoderm destined for the heart and aortic arches.
Histochemistry of the aldosterone‐stimulated urinary bladder of the toad, Bufo marinus
Authors: Symonds Daniel A. , Lentz Thomas L. 
Published: February 2005

AbstractHistochemical changes were observed in the epithelium of the toad urinary bladder following in vitro and in vivo stimulation by aldosterone to determine the cell types affected by this hormone. A marked pyrinophilia was observed in comparison to control tissue affecting all cell types, as well as slight increases in cytoplasmic PAS staining within the granular cells, under both sets of conditions. An increased number of mitochondria was demonstrated with the PTAH stain within the granular cells under in vivo conditions but not in vitro. Under in vivo conditions, marked increases in the enzymes of the oxidative pathway (DPND, TPND, SDH, and cytochrome oxidase) were observed in granular cells. Enzymes of the oxidative pathway were unchanged under in vitro conditions was more intensely localized to the cell membrane and cytoplasm of all cells. Granular cells from in vitro studied tissue were slightly more reactive for G6PD and 6PGD than control tissue; granular cells were even more heavily reactive for these enzymes under in vivo conditions. Thus, under prolonged aldosterone stimulation, the granular cell approached the histochemical profile of the mitochondria‐rich cell. The hormone may therefore act upon the granular cell, which comprises the largest number of cells within the epithelium, as well as the mitochondria‐rich cell.
Intracellular distribution of mucosubstances in the major sublingual gland of the rat
Authors: Enomoto Shoji , Scott Bronnetta L. 
Published: February 2005

AbstractThe intracellular distribution of mucosubstances in the acinar cells of the rat sublingual gland has been studied at the electron microscopic level by means of two histochemical techniques: PA‐silver methenamine for the detection of vicinal glycols and colloidal thorium for the detection of polyanions. By both methods the secretory granules in the mucous acinar cells were selectively stained. The reaction products were visualized as dense closely packed precipitates covering the entire matrix of the individual mucous granules. Similar reaction products were also often observed within the Golgi apparatus of the mucous cells. In striking contrast, the secretory granules and Golgi apparatus of the demilunar cells exhibited no demonstrable selective staining by either method. It is concluded that the secretory granules of the mucous acinar cells are largely composed of mucosubstances containing vicinal glycols and polyanions and that the secretory granules in demilunar cells contain no demonstrable content of such mucosubstances.
Direct contribution of the cytotrophoblast to the syncytiotrophoblast in the diffuse labyrinthine endotheliochorial placenta of the bat
Authors: Stephens R. J. , Cabral L. 
Published: February 2005

AbstractIn the molossid bat, Tadarida brasiliensis cynocephala, there is a prominent diffuse endotheliodichorial placenta over the parietal area of the uterus prior to mid‐gestation. During the neural groove stage the syncytium rapidly increases in quantity, and cells from the cytotrophoblast have been observed being contributed to the syncytium. The transitional cells become swollen and the plasma membranes between the syncytium and the transitional cell fuse, become porous, and rupture. The contents of the transitional cell then “flow” into the syncytial area.
The sarcoplasmic reticulum and development of z lines in skeletal muscle fibers of fetal and postnatal rats
Authors: Walker Sheppard M. , Edge Maxine B. 
Published: February 2005

AbstractIn electron microscope examinations of leg muscles from fetal and postnatal rats the development of SR tubules precedes the development of Z lines and the formation of fibrils, thus showing that a function of SR in Z line development is possible. Early stages of fibril formation reveal very small Z lines (0.06 μ thick) which are encircled by SR tubules separated from the Z lines by a space about 100 Å wide, and this space is traversed by electron‐opaque strands which appear to be connections between SR tubules and Z lines. The encircling SR tubules are observed from the beginning to the completion of Z line development. The small Z lines contain dense lines transversely oriented between thin filament tips that resemble transversely oriented dense lines found in fully developed Z lines. It is concluded that Z line enlargement involves growth in circumference of encircling SR tubules as the tubules incorporate additional layers of thin filament tips. It is suggested that the substance represented by electronopaque strands connecting SR tubules and Z lines might provide precursors for the substance represented by transversely oriented dense lines between thin filament tips.
Functional anatomy of the cardiac nerves in the baboon
Authors: Randall Walter C. , Armour J. Andrew , Randall David C. , Smith Orville A. 
Published: February 2005

AbstractIn 17 anesthetized baboons, the autonomic innervation of the heart was carefully exposed and electrically stimulated to determine the course of fibers having direct inotropic and/or chronotropic actions. The superior cervical and nodose ganglia are intimately associated by means of short but large interconnections, and the sympathetic and parasympathetic trunks descend with the carotid artery in a common epineural sheath. The middle cervical ganglion is invariably well defined and completely separated from the vagus trunk in the upper portion of the thoracic cage. Direct nervous connections between the sympathetic and vagal trunks are frequent at all levels within the thorax. Both systems also send small nerves into the phrenic and recurrent laryngeal nerves. Separate inferior cervical and first thoracic ganglia were not found, but rather, a large and well defined stellate ganglion extending across the heads of the first and second ribs. The stellates are connected to the middle cervical ganglia by means of both dorsal and ventral ansae subclavia of varying size. Although fine nerves arising from the upper thoracic trunk were located, they appeared to have no direct inotropic or chronotropic actions. The major sympathetic and parasympathetic nerves converge upon richly interconnected dorsal and ventral cardiopulmonary plexuses and several minor (superior vena cava, left atrial, pulmonary veins) plexuses. Both ipsilateral and contralateral control of cardiac function is possible through these pathways. The baboon cardiac innervation thus appears to resemble that of man in some respects and the dog in others.