bluuebunny/crossref_metadata_2025_split huggingface dataset:
Patterns of mitosis in hamster epidermis
Authors: Mackenzie I. C. , Zimmerman K. L. , Wheelock D. A. 
Published: February 2005

AbstractAlignment of the flattened keratinizing cells of the upper strata of mammalian epidermis leads to the formation of columnar units of structure. In mouse epidermis, mitoses have been found to occur relatively infrequently in the region beneath the center of each cell column where a non‐keratinocyte dendritic cell, usually with features typical of an epidermal Langerhans cell, is situated. The observed pattern of mitosis could therefore be due either to displacement of central keratinocytes by Langerhans cells or indicate some control of keratinocyte proliferation related either to the Langerhans cells or to the overlying cell columns. No relationship exists between the position of Langerhans cells and epidermal cell columns in hamster epidermis but measurement of the position of mitosis has shown a reduced frequency of occurrence of mitosis beneath the central region. This pattern of mitosis is therefore unrelated to Langerhans cells and appears to reflect differences in the mitotic potential of basal keratinocytes which could be associated with feedback from the overlying cell columns or with an intrinsic pattern of basal cell activity.
Light, fluorescence and electron microscopic studies of rabbit subclavian glomera
Authors: Hansen John T. , Yates Robert D. 
Published: February 2005

AbstractThe subclavian glomera (aortic bodies) of young New Zealand white rabbits were studied with the light, fluorescence, and electron microscopes. Two cell types were identified: type I, granule‐containing (chief) cells, and type II, agranular (sustentacular) cells. The type I cells possessed large nuclei, the normal complement of cytoplasmic organelles and numerous electron‐opaque cytoplasmic granules. The type II cells were agranular with attenuated cytoplasmic processes which partially or completely ensheathed the type I cells. The glomera were well vascularized. Capillary endothelial cells contained numerous pinocytotic vesicles, but few fenestrae. Two profiles of nerve terminals were observed. One, apposing the type I cells, contained numerous electron‐lucent vesicles, several dense‐cored vesicles, mitochondria and possessed membrane specializations resembling those usually observed in synaptic zones. The other profile contained abundant mitochondria and a few electron‐lucent and densecored vesicles. Structural specializations were not observed on the apposed membranes of these terminals or adjacent to type II cells.Fluorescence histochemistry revealed an intense yellow‐green fluorescence in the glomera, which indicated the presence of biogenic amines, possibly primary catecholamines or an indolamine. The electron‐opaque granules observed in the type I cells were believed to be the storage sites for these amines. The subclavian glomera were found to be morphologically similar to the carotid body which is a known chemoreceptor.
An electron microscopic study on the effects of reserpine on the subclavian glomera of the rabbit
Authors: Hansen John T. , Yates Robert D. , Chen I‐Li 
Published: February 2005

AbstractYoung male and female New Zealand white rabbits were given a daily subcutaneous injection of reserpine (Serpasil, Ciba; 3 mg/kg) for two days and were sacrificed 24 hours after the last injection. The subclavian glomera (aortic bodies) were processed for electron microscopy to determine the effects of this biogenic amine depleting agent on the electron‐opaque cytoplasmic granules of the parenchymal type I cells.Observations of glutaraldehyde‐osmium tetroxide fixed glomera from reserpinized animals showed a slight decrease in granule density of the type I cells. Glomera fixed in glutaraldehyde and incubated in potassium dichromate (pH 4.1) demonstrated a reduction in granule opacity following reserpine treatment. Control glomera incubated in potassium dichromate displayed electron‐opaque granules. These results indicate that reserpine does deplete the amines without granule disappearance or changes in granule population. The positive reaction of the control tissue granules to potassium dichromate incubation suggests that the predominant biogenic amines in the electron‐opaque granules are unsubstituted monoamines. Persistence of the opaque granules following reserpinization and glutaraldehyde‐osmium tetroxide double fixation, may be due to aminebinding protein within the granules. The mode of granule depletion could not be ascertained with certainty.
Immunocytochemical localization of somatostatin in cell bodies of the rat hypothalamus
Authors: Elde Robert P. , Parsons Jonathan A. 
Published: February 2005

AbstractCell bodies of small to moderate‐sized neurons in the female rat hypothalamus were stained specifically for somatostatin (SRIF) by means of the unlabeled antibody‐peroxidase‐antiperoxidase immunocytochemical method. SRIF‐positive perikarya were scattered throughout the periventricular nucleus in a limited region extending from the middle of the optic chiasm to the rostral margin of the median eminence. The same neurons were revealed with either rabbit (R) or guinea pig (GP) anti‐SRIF antisera. Positive cell bodies were more readily assessed with GP antibodies because nonspecific background staining was much less with these than with R anti‐SRIF. Positive perikarya were not observed in other hypothalamic nuclei and ependymal elements were also immunocytochemically negative.
A minimum‐surface mechanism to account for the organization of cells into columns in the mammalian epidermis
Authors: Menton David N. 
Published: February 2005

AbstractIt has recently been discovered that the stratum corneum and superficial living epidermis of mammalian skin are organized into neat vertical columns of interdigitating cells. The mechanism for this organization has not yet been determined. This study shows that the stacked organization is not unique to the epidermis but also occurs in cork cambium and the pith of woody plant stems. The structural and spatial organization of the stacked cells in these tissues were compared and found to approximate closely the shape of Kelvin's minimum‐surface polygon, the tetrakaidecahedron. Paper models of flattened tetrakaidecahedra were constructed and found to stack in columns of interdigitating units which are consistent with all of the structural details seen in stacked cells observed under the light and the scanning electron microscopes. Indeed, only polygons of this type are capable of aggregating without interstices in the manner of the stacked cells. A study of stacked arrays of these models has revealed a mechanism by which the epidermis might become organized in columns of stacked and interdigitating cells. The proposed mechanism assumes that cells within an array seek the smallest possible surface‐to‐volume ratio and, under appropriate conditions, form stacked tetrakaidecahedra.
Platelets, endothelial cells and macrophages in the spleen. An ultrastructural study on perfusion‐fixed organs
Authors: Elgjo Ragna Følling 
Published: February 2005

AbstractRabbit spleens have been examined after perfusion fixation with and without prior washing with various fluids. The platelets were stored in the splenic sinuses and in the cord spaces as single platelets, or in loosley packed aggregates which appeared to be anchored to the endothelium by one or a few platelets. After washing prior to fixation most of the platelets disaggregated and regained their normal shape. Some platelets adhered to morphologically normal endothelium even after prolonged perfusion. Occasionally, platelets were observed inside splenic endothelial cells. Others were closely associated with macrophages, many of which also contained engulfed platelets.There was no morphological evidence of a particular platelet population being retained in the spleen after washing.In the sinuses special granule‐rich cytoplasmic structures were observed. They were interposed between ordinary endothelial cells and contained a large number of small lysosome‐like granules. Nuclei were never observed in these structures, probably because they consisted of pseudopod‐like protrusions. Their origin and function are discussed. They may represent actively phagocytizing elements.
Hysterectomy in the rat: Surgical disruption of the vascular channels reduces number of ova shed
Authors: Peppler Richard D. 
Published: February 2005

AbstractCycling rats were hysterectomized and/or unilaterally ovariectomized (ULO) on day 2 (metestrus). Collateral blood supply to the remaining ovary via the uterine artery was left intact or disrupted. Animals were killed in metestrus after one complete estrous cycle. Control rats were also killed at this time.Counts of tubal ova revealed that intact rats ovulated an average of 4.4 ± 0.4 eggs per ovary (N = 8). Following ULO, rats (N = 8) ovulated 9.6 ± 0.2 eggs. Ligation of the uterine artery decreased the number of eggs ovulated in ULO rats (N = 8) to 5.4 ± 1.1. Hysterectomized rats (N = 8) ovulated 4.8 ± 0.5 eggs per ovary. If the blood supply was disrupted, a reduction to 2.7 ± 0.2 eggs per ovary occurred (N = 8). Hysterectomized and ULO rats (N = 8) ovulated 10.3 ± 0.4 eggs from the remaining ovary but only 5.0 ± 1.0 eggs if the collateral blood supply of the uterine artery was not intact (N = 10).The results demonstrate that disruption of the vascular channels during the surgical procedures of hysterectomy and/or ULO results in a reduction of the expected ovulation number.
Fine structure of differentiating ameloblasts in the kitten
Authors: Kallenbach Ernst 
Published: February 2005

AbstractThe fine structure of differentiating ameloblasts was studied in the lower second molar of 1‐week‐old kittens after perfusion fixation with and without subsequent decalcification.The differentiation zone was divided into three phases. In Differentiation 1, ameloblasts are about 27 μm long and face an uninterrupted basal lamina. The predentin adjacent to the basal lamina contains a few collagen fibrils oriented mainly at right angles to the ameloblast surface. This specialized predentin forms a well‐defined layer, up to 1.5 μm thick, referred to as the junctional layer. In Differentiation 2, ameloblast processes extend through the basal lamina and the thickness of the junctional layer. The processes consist of cytoplasmic sheets forming a honeycomb‐like network. Dentin starts to calcify after process‐formation is underway. Two distinct types of odontoblast processes, having different shapes and contents, come in contact with the ameloblasts and push into the ameloblastic layer. In Differentiation 3, stippled material appears in the extracellular spaces between ameloblasts. Later, stippled material‐like substances appear in the predentin close to the ameloblast apex and close to odontoblast processes within the dentin. Ameloblasts now are up to 40 μm high. Enamel secretion starts in small circumscribed areas which gradually enlarge, leading to the disappearance of the ameloblast processes. These findings are compared with results obtained in other species, including man, and their possible functional significance is discussed.
Renal vasculature of the trout demonstrated by scanning electron microscopy, compared with canine glomerular vessels
Authors: Anderson Bettina G. , Anderson Wesley D. 
Published: February 2005

AbstractIn order to gain additional information regarding renal circulatory patterns, we have used both ink and resin injections to study the arterial supply to the mesonephric kidney of trout. Arterial injections through the dorsal aorta with ink were made for histological preparations in which the length, termination and relationship of glomerular vessels were examined. Similar injections with methyl methacrylate were made in preparation of corrosion casts to provide us with gross replicas of the aortic branches to the kidney as well as casts of glomerular structure for scanning electron microscopy.The sequence of vessels through which arterial blood passed to the renal corpuscle and ultimately to the uriniferous tubules was traced. Each afferent arteriole was found to terminate in three to six brancehs which formed anastomosing circuits of capillaries; these vessels reunited at the hilum to form a single efferent arteriole. The efferent arterioles in turn traveled a short distance to peritubular capillary beds and sinusoids.Morphological evidence was found for preglomerular sphincter‐like action only. The glomerular vessels were found to be similar to, although less complex than, those of the outer and mid‐cortical regions of the dog kidney.
Morphogenesis of fetal rat duodenal villi
Authors: Mathan Minnie , Moxey Pamela C. , Trier Jerry S. 
Published: February 2005

AbstractTo study the structural features of fetal rat duodenal mucosa associated with histogenesis of villi, duodena from 15‐ to 19‐day fetuses were examined by light and electron microscopy. The duodenal epithelium of 15‐to 18‐day fetuses was stratified. Distinctive junctional complexes associated with membrane‐bounded vesicles and cilia‐like structures were seen in the deeper epithelial layers at 15 and 16 days. Small lumina, designated “secondary lumina,” lined with a variable number of microvilli developed between epithelial cells at these junctional complexes during the sixteenth through eighteenth days. Degenerative changes and exfoliation of superficial epithelial cells were obvious in 17‐ and 18‐day fetuses. In 18‐day fetuses, aggregates of mesenchyme had invaginated the basal aspect of the stratified epithelium. Concomitantly, the number of epithelial layers overlying these mesenchymal projections was decreased. In 19‐day fetuses, well formed, short duodenal villi lined by a simple columnar epithelium which included goblet and endocrine cells were evident. Injection of ferritin into the main duodenal lumen of 17‐day fetuses failed to reveal continuity between the main lumen and the secondary lumina. However, continuity between many secondary lumina and the main lumen was demonstrated in 18‐day fetuses. Thus, major morphological features associated with villus formation in fetal rat duodenum include: (1) formation of many secondary lumina in primitive stratified epithelium, (2) eventual fusion of these lumina with the main duodenal lumen, by their continued growth coupled with exfoliation of degenerating superficial layers and (3) upward growth of mesenchyme towards the lumen as cell exfoliation and expansion of secondary lumina take place.
Fetal and neonatal rat pancreas in organ culture age‐related effects of corticosterone on the acinar cell component
Authors: McEvoy Robert C. , Hegre Orion D. , Lazarow Arnold 
Published: February 2005

AbstractFetal rat pancreas (ages 16 to 22 days postcoitum) and neonatal pancreas (4 days postnatal) were grown in organ culture for four days. The medium consisted of chick embryo extract and rooster serum either with or without the addition of corticosterone (3 × 10−5 M). Acinar cell differentiation was assessed using quantitative light microscopic linear scanning of tissue sections and enzymatic analysis of amylase in the culture media and in the explants. In the younger fetal tissue of 16 and 18 days postcoitum exocrine differentiation continued in vitro. The effect of corticosterone was an enhancement of the degree of in vitro differentiation. Even with corticosterone, however, the degree of differentiation in vitro was less than that observed during a similar period in vivo. In differentiated pancreas (20‐ and 22‐day fetal and 4‐day neonatal) the acinar pancreas degenerated under control conditions and a selective growth of the endocrine pancreas was observed. The addition of corticosterone to the media resulted in a maintenance of the differentiated state of the acini except in 22‐day fetal tissue in which the acini were not preserved. The differences between these results and the work of other investigators and the possible in vivo role of adreno corticosteroids in exocrine pancreatic differentiation is discussed.
Genetic spina bifida occulta in the mouse
Authors: Hollander W. F. 
Published: February 2005

AbstractSpina bifida occulta is one of the major effects of the recessive mutant “snubnose” (symbol sno). Linkage tests have located this mutant in chromosome 4. Defective spinal arch formation typically includes the lumbar and often the posterior thoracic and sacral vertebrae. There is great variation in detail, from nearly normal closure to a trough‐like spinal column. Causes of the variation are not understood. Severely affected specimens may also have defective anterior thoracic vertebrae and reduced size of the sacral vertebrae, with kyphosis. The tail is essentially normal. No external lesion or myelomeningocele has been found, but there have been some instances of paralysis of the hind limbs, possibly from injury. The spinal cord seems normal as a rule, and pigmentation is normal. Embryological study has not been attempted, but the condition seems to be primarily osteogenic in origin.
Type II pulmonary epithelial cells of the newborn opossum lung
Authors: Krause William J. , Cutts J. Harry , Leeson C. Roland 
Published: February 2005

AbstractThe air chambers of the newborn opossum are lined by a respiratory epithelium which appears similar to that lining alveoli of other species. The type II pulmonary epithelial cell is cuboidal in shape, shows apical microvilli, several Golgi complexes, lipid droplets, and numerous cytosomes. The cytosomes contain osmiophilic lamellae and are similar in appearance to whorls of osmiophilic material lying free within the alveolar lumina and on the surface of the respiratory lining epithelium. In the newborn opossum lung, examination of the air chambers with the scanning electron microscope permits the observation of several type II pulmonary epithelial cells in a single field. The potential use of the air chamber of the newborn opossum as an experimental model is suggested.
Cations in the rat pars distalis ultrastructural localization
Authors: Schechter Joel E. 
Published: February 2005

AbstractPituitary glands of female Sprague Dawley rats were fixed using the potassium pyroantimonate‐osmium tetroxide technique by immersion or vascular perfusion. Both fixation procedures resulted in similar patterns of cation localization visualized as electron‐dense precipitate within cells of the pars distalis. Nuclei were prominent sites of localization. Cytoplasmic precipitate occurred in association with the endoplasmic reticulum, typically within the cisternal spaces, and also was localized within the mitochondrial matrix and cristae, as well as Golgi membranes, small Golgi‐associated vesicles, and multivesicular bodies. Immature secretory granules often contained precipitate between the core material of the granule and the enclosing smooth membrane. Frequently small antimonate‐containing vesicles bordered the immature secretory granules. Precipitate was variable in secretory granules of more mature appearance although precipitate was apparent occasionally just within a granule's enclosing membrane. Granules closest to the plasma membrane often contained increased amounts of precipitate and small vesicles containing precipitate were observed fusing with them. Instances of granule release by emiocytosis often revealed a clustering of precipitate behind the core material away from the emiocytotic stoma, as well as at the stoma and frequently an increased electron density of filamentous material radiating from the granules' enclosing membranes or from the adjacent plasma membrane. Exposure of section material to the chelating agents EGTA and EDTA indicate that calcium is the primary cation localized within the cytoplasm of these secretory cells. These findings are consistent with a role for calcium as a facilitator in the processes of transport and release of secretory granules.
Elastic fiber formation in monolayer and organ cultures of chondrocytes isolated from auricular cartilage
Authors: Moskalewski Stanislaw 
Published: February 2005

AbstractChondrocytes were isolated from auricular cartilage of immature rabbits and maintained in monolayer or organ culture for 14 days. In both types of culture the chondrocytes formed conspicuous elastic fibers. In monolayer culture the fibers could be identified by orcein staining in the culture dish. Electron microscopy of organ cultures revealed the presence of two basic components of elastic fibers, i. e. microfibrils and elastin.
Fine structure of satellite cells in growing skeletal muscle
Authors: Schultz Edward 
Published: February 2005

AbstractThe morphology of satellite cells was investigated in skeletal muscle from mice of various ages between 7 days and 50 weeks. Satellite cells of very young muscle had abundant cytoplasm which was rich in organelles. Free ribosomes were abundant and usually arranged into polysomes of 5–6 units. Cisternae of rough endoplasmic reticulum were heavily studded with ribosomes and occupied the polar regions of the cytoplasm. Marked dilations of the cisternae, filled with an amorphous electron‐lucent material, were a frequent and characteristic feature of satellite cells of very young muscle. The cytoplasm of young cells also contained a well developed Golgi apparatus as well as numerous mitochondria, microfilaments and microtubules. With increasing age there was a rapid reduction in organelles both qualitatively and quantitatively. For example, as the number of ribosomes decreased, their organization into polysomes was lost. The rough endoplasmic reticulum was present in cells of older muscle merely as small isolated rofiles that lacked dilations. These and other features demonstrated during this study are consistent with the concept that satellite cells are metabolically very activie in young muscle but rapidly become quiescent as the animal grows older.
Relationship between the adrenal cortex and thymic involution in “lethargic” mutant mice
Authors: Dung H. C. 
Published: February 2005

AbstractTo determine if the adrenal gland plays a role in the thymic involution which occurs spontaneously in “lethargic” mutant mice, three different studies were made. Morphological studies were made first to determine if there was an indication of histological changes in the adrenal glands. Next, serum levels of corticosterone were measured by radioimmunoassay. Finally, mice were unilaterally adrenalectomized to see if such treatment would improve various symptoms of “lethargic” mutants. Results of the studies showed that lipid granules in the cortical cells of “lethargic” mutants were greatly reduced in number during the time of spontaneous thymic involution, and the mutant mice had a significantly higher level of serum corticosterone than the normal controls. Mutant mice unilaterally adrenalectomized at 15 days of age showed a marked improvement in their condition and their mortality rate decreased. It is concluded that spontaneous thymic involution of “lethargic” mutants is probably associated with adrenocortical hypersecretion.
Surface morphology in the olfactory epithelium of normal male and female rhesus monkeys
Authors: Saini K. D. , Breipohl W. 
Published: February 2005

AbstractOlfactory epithelium of male and female rhesus monkeys has been studied by transmission electron microscopy. It is shown that the epithelial surface differs greatly between male and female monkeys. Differences are most prominent between male and preovulatory females. During the ovulatory phase of the ovarian cycle remarkable histological alterations occur especially in the sustentacular cells. These alterations are correlated with physiological and behavioral phenomena demonstrating a possible structural basis for the changes in olfactory threshold in relation to sex hormones.