bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurocytogenesis. I. Neurofibrils, neurofilaments, and the terminal mitotic cycle
Authors: Sechrist John W. 
Published: February 2005

AbstractInitial cytodifferentiation of neuroblasts in the retina of chick embryos was investigated by means of silver impregnation, H3‐thymidine autoradiography, and electron microscopy. Utilization of various combined procedures with the same initial fixative demonstrated that the results of neurofibrillar staining are complementary, not contradictory, to information obtained from both autoradiography and electron microscopy.The question of a homogeneous versus a non‐homogeneous cell population within the neural epithelium was clarified by the closely related appearance of neurofibrils to the terminal mitotic cycle of some presumptive neuroblasts. Neurofibrils were observed in certain apolar pre‐division cells as well as in pairs of transitional apolar and bipolar daughter cells which apparently do not remain in the neural epithelium. At the ultrastructural level, aggregates of 60 Å neurofilaments were observed in configurations that corresponded to neurofibrillar networks. As the bipolar neuroblast moves into the ganglion cell layer, it would appear that much of the neurofibrillar substance is transported within the elongating peripheral process which becomes the optic nerve fiber. Further investigation of the relationship of neurofilaments to neurotubules in the neuroblast undergoing cytodifferentiation is now in progress.
Ultrastructural studies on fetal and early postnatal mouse ovaries. I. Histogenesis and organogenesis
Authors: Odor D. Louise , Blandau Richard J. 
Published: February 2005

AbstractOvaries of fetal mice obtained during the twelfth to eighteenth day of gestation and from the first to third postnatal day have been studied by electron microscopy. The interrelationships of follicle cells to oögonia and to connective tissue cells have received special attention. On day 12, when the female gonad can first be distinguished, relatively few large oögonia are visible. These are loosely aggregated and are accompanied by only a few follicle cells.On days 13 and 14 loose groups of oögonia become better demonstrated, and now are always surrounded peripherally by follicle cells. Beginning on day 14 very thin cytoplasmic processes of the follicle cells are interposed between adjacent oögonia. Subsequently, by following this process the follicle cells are drawn into the groups of oögonia or oöcytes. Increasing numbers of connective tissue cells and capillaries are growing into the cortex from the medulla and hilar regions. By day 18 and postnatal day 1 this ingrowth has separated the groups of oöcytes and follicle cells further. By postnatal days 2 and 3 most oöcytes have become enclosed by a follicular epithelium of either flattened, cuboidal or columnar cells. Many stages of zona pellucida formation can be recognized. It is postulated that the manner of fetal and early postnatal differentiation of the ovary explains a number of follicular configurations which deviate from the normal. At no time have cords of cells been observed to originate from germinal epithelium. By contrast the underlying tunica albuginea is derived by ingrowth of cells from the medulla.
Origin and renewal of goblet cells in the epithelium of the mouse small intestine
Authors: Merzel J. , Leblond C. P. 
Published: February 2005

AbstractThe epithelium of duodenum, jejunum and ileum was investigated in adult female mice given an injection of3 H‐thymidine and sacrificed at times varying from one hour to 14 days later. The tissues were fixed by perfusion with paraformaldehyde and embedded in Epon. One micron thick sections were cut singly or serially, radioautographed and stained with iron hematoxylin and safranin O. In addition, reconstruction of a crypt was made from serial sections of jejunum.The reconstruction of a crypt shows the well known columnar, goblet, Paneth, and argentaffin cells. There are also little known cell types referred to as oligomucous and granulo‐mucous and pale cells with or without mucus. Of these cells, the only numerous ones are the oligomucous cells, which are located in the lower half of the crypts and contain a few or even only one mucous globule. In the electron microscope, they display long cisterns of rough endoplasmic reticulum parallel to the lateral cell membrane and similar to those observed in goblet cells.In radioautographs of the crypts neither goblet cells, nor Paneth cells, nor argentaffin cells show mitosis or label one hour after3 H‐thymidine injection. Granulo‐mucous and pale cells are only rarely labeled. In contrast, columnar and oligomucous cells frequently take up label and undergo mitosis. By 12 hours after injection labeled goblet cells have appeared. Since at that time 3 H‐thymidine has left the circulation, the label must have been acquired by transformation of labeled columnar or oligomucous cells. Furthermore, since transitional forms between oligomucous and goblet cells are common, it is concluded that oligomucous cells are those which directly transform into goblet cells.Eventually, like columnar cells, labeled goblet cells migrate to the villus epithelium, climb to the villus tip and fall into the lumen.Although oligomucous cells fit the requirements for goblet cell precursors, not enough of them are labeled to account for the rate of renewal of goblet cells. It is therefore speculated that some undifferentiated columnar cells at the base of the crypts participate in the production of oligomucous cells, which in turn yield goblet cells.
Radioautographic studies of glycogen synthesis in the striated muscle of rat tongue
Authors: Coimbra Antonio 
Published: February 2005

AbstractGlycogen synthesis was studied in rat tongue striated muscle after administration of 3H‐glucose using light and electron microscope radioautography. Neither fasting nor addition of unlabeled glucose were needed to produce incorporation of 3H‐glucose into glycogen, the only radioactive substance found in the tissue. Intense radioautographic reactions indicating glycogen synthesis were already seen 20 minutes after injection and were preferentially located over glycogen accumulations in the intermyofibrillar spaces. A striking variation of silver grain density from fiber to fiber, was a somewhat unexpected finding in a muscle consisting of fibers of uniform metabolic type. Decrease in grain counts at the 90‐minute interval suggested a rapid turnover of muscle glycogen. In agreement with this, there were no morphological signs of glycogen accumulation on glucose administration. PA‐Schiff staining, as well as the number of glycogen granules in electron micrographs, did not increase, nor did granule diameters change significantly during the experiment. Electron microscope radioautographs showed all silver grains to be located over or very near glycogen granules and sarcoplasmic spaces. While all newly‐formed glycogen seemed associated with preexisting granules, there was no evidence for the participation of the sarcoplasmic reticulum in glycogen synthesis.
Origin and early migration of primordial germ cells in the chick embryo: A study of the stages definitive primitive streak through eight somites
Authors: Clawson Robert C. , Domm L. V. 
Published: February 2005

AbstractThe germinal crescent in the chick embryo is characterized by small, PAS‐positive, nonglycogen granules from 1.5 to 5 μ in diameter. The primordial germ cells (PGCs) were found to originate in and separate from the germinal crescent endoderm through stage 7 (2 somites). Shortly after separation most of the granules in the PGCs lost their organization and the PAS‐positive material was distributed irregularly throughout the cytoplasm. A few of these granules remained within the cells indefinitely. Glycogen of an agranular nature which had shifted to one pole of the cell was observed at stage four. Granular glycogen which was distributed throughout the cytoplasm was not observed prior to stage 7 or 8.Cell counts on individual embryos showed noticeable variations as to the number of germ cells between embryos of the same stage. For example, in stage 4 embryos the minimum number of cells counted, including attached and free, was 78 and the maimum 169, while in stage 9 the minimum was 83 and the maximum 469 cells. After separation the germ cells were observed almost anywhere between the ectoderm and the endoderm although the majority remained in the area where they originated.
The dermal chromatophores of Anolis carolinensis (reptilia, lguanidae)
Authors: Alexander Nancy J. , Fahrenbach Wolf H. 
Published: February 2005

AbstractSkin of the back, belly, dewlap and parietal eye were studied as illustrations of the principal variations of chromatophore arrangement and color range present in Anolis carolinensis. The fine structure of the chromatophores, disposed in sharply stratified layers, was investigated. The most superficial chromatophore layer consists of xanthophores, which impart a greenish‐yellow color to the skin. These cells are filled with two types of membrane‐bounded inclusions containing pteridines and carotenoids, respectively. Basal to the xanthophores is a 2–4 cell‐deep layer of iridophores. These cells are filled with undulating layers of birefringent rodlets, presumably guanine, arranged parallel to the skin surface. The most basal chromatophores are large melanophores, positioned above a thick collagenous basement lamella. Migration of melanin granules into the dendritic processes, which terminate at the dermoepidermal junction, cause the lizard to change from green to brown. The back skin, which ranges in color from bright green to brown, contains the full complement of dermal chromatophores. The xanthophore region is much reduced in the cream‐colored belly. The dewlap, which is bright red when extended, bears a thick layer of iridophores through which are scattered melanophores, and erythrophores containing red pigment. The dermis over the parietal eye contains only xanthophores and a basement lamella.
Innervation of the abdominopelvic ureter in the cat
Authors: Elbadawi Ahmad , Schenk Eric A. 
Published: February 2005

AbstractThe distribution of cholinergic and adrenergic nerves in the cat ureter was studied by specific histochemical techniques for acetylcholinesterase and norepinephrine. The innervation of the ureter is characterized by (1) a generalized dual cholinergic and adrenergic nerve supply, (2) the presence of muscular innervation, (3) a continuity of terminal muscular and vascular nerves, (4) a widespread distribution of ganglion cells except in the pelviureteric area and (5) regional variations in the density of both cholinergic and adrenergic elements.On the basis of these findings, it is suggested that in the cat ureter peristalsis has a myogenic origin in the proximal end of the ureter, but its distalward propagation along the abdominal and pelvic segments is controlled by a dual sympathetic and parasympathetic influence which is mediated in part through a system of intrinsic ureteric ganglion cells.
The fine structure of the human corpus luteum of early pregnancy and during the progestational phase of the menstrual cycle
Authors: Crisp Thomas M. , Dessouky Dessouky A. , Denys Francis R. 
Published: February 2005

AbstractThe fine structure of granulosa lutein cells and theca lutein cells of human corpora lutea of early pregnancy and during the progestational phase of the menstrual cycle (i.e., 1 day, 7 days and 9 days after estimated ovulation) is described. Granulosa lutein cells of early pregnancy are distinguished from theca lutein cells in having: (1) a more homogeneous, electron‐lucent nuclear matrix, (2) enlarged pleomorphic mitochondria with irregularly‐shaped, osmiophilic inclusions, (3) numerous isolated regions of the Golgi complex, (4) abundant whorls of granular and agranular endoplasmic reticulum, (5) a folded‐membrane complex, (6) numerous bundles of 50 Å filaments and (7) patches of elongated microvilli bordering intercellular and intracellular canaliculi.Furthermore, granulosa lutein cells of early pregnancy are distinguished from granulosa lutein cells of corpora taken during the progestational stage of the menstrual cycle by the greater abundance of granular and agranular endoplasmic reticulum, the presence of concentric membranous whorls and large spherical mitochondria, increases in membrane‐bound granules and a more extensive development of intracellular canaliculi. These differences are related to the high titers of serum gonadotrophin (s) during early gestation.The morphology of human corpora lutea is compared with steroidogenic tissues of other species and is correlated with the capacity of human corpora lutea to synthesize estrogens in addition to progestogens. Based upon morphological evidence, it is suggested that in addition to elaborating steriod hormones, corpora lutea may also secrete a proteinaceous product, perhaps relaxin.This work was presented as a demonstration to the eighty‐second annual session of the American Association of Anatomists in April, 1969. An abstract has been published (Anat. Rec., 163: 336, '69).
Origin and distribution of portal blood in the cat and the rabbit
Authors: Heath Trevor , House Brian 
Published: February 2005

AbstractThe portal vein in the rabbit is formed by union of the gastrosplenic vein, which extends caudally and to the right, and the relatively larger and cranially directed mesenteric vein, formed from cranial and caudal mesenteric and caudal pancreaticoduodenal tributaries. The gastroduodenal vein, which receives blood from the distal pylorus, greater omentum, pancreas and duodenum, joins the rabbit portal vein opposite the branch to the caudate lobe. In the cat, the portal vein is formed by the junction of the gastrosplenic, which is directed transversely or cranially, and the mesenteric, and receives two main tributaries: the gastroduodenal, which is the main vein from the stomach, and the cranial pancreaticoduodenal.When 131I‐rose bengal was injected into the spleen of conscious standing cats and entered the portal vein in the gastrosplenic, it was distributed preferentially to the right branch and the left lateral ramus of the left branch. In the rabbit, there was no evidence for preferential distribution of splenic blood, but blood from the cranial mesenteric vein was distributed preferentially to the right and caudate branches and that from the caudal mesenteric to the caudate. This distribution was affected by the entry of blood in the gastrosplenic vein. Although statistically significant differences did occur in the intrahepatic distribution of blood derived from the portal tributaries, the absolute differences were small.
Morphology and histochemistry of the soleus muscle from normal and exercised rats
Authors: Edgerton V. Reggie 
Published: February 2005

AbstractSixty white rats were divided into three groups which consisted of (1) rats individually housed in cages having dimensions of 24 × 18 × 18 cm, (2) rats housed in similar cages and forced to swim for 30 minutes a day with a weight equal to 3% of body weight, and (3) rats housed in individual cages equipped with a revolving drum permitting each rat to exercise at will. The third group was also forced to swim for two 30‐minute periods each day with a weight equal to 4% of body weight attached to the tip of the tail. The experimental treatments lasted for a period of 52 days. The rats were exercised six days per week. The day after the final treatment, the left soleus, plantaris and gastrocnemius muscles were removed, frozen, and serial sections treated with a variety of histochemical and histological procedures.Necrotic, angular and split fibers were observed in the soleus muscle but not the gastrocnemius and plantaris of sedentary, moderately exercised and heavily exercised rats. These features were characteristic of the seemingly normal soleus of sedentary and chronically exercised rats and were not manifestations of any apparent myopathy. No difference was found in the number of fibers that were longitudinally split. However, the number of fibers (“subfibers”) resulting from split fibers was greater in the moderately exercised than in the sedentary rats, but greatest in the heavily exercised group.
Selective inhibition by chloramphenicol of ACTH‐induced reorganization of inner mitochondrial membranes in fetal adrenal cortical cells in tissue cultures
Authors: Kahri Arvi I. 
Published: February 2005

AbstractTissue cultures of fetal rat adrenals were used to study effects of chloramphenicol on the ACTH‐induced synthesis of mitochondrial inner membranes in the cortical cells. Chloramphenicol alone added to the culture medium in concentrations of 0.003, 0.03, 0.3, and 0.6 μ mole/ml/6 days induced no changes in the ultrastructure of cortical cells. Chloramphenicol in concentrations of 0.3 and 0.6 μ mole/ml/6 days given together with 100 mu/ml/6 days of ACTH inhibited completely the ACTH induced changes of mitochondrial inner membranes (formation of 600 Å vesicles). Chloramphenicol in concentrations of 0.003 μ mole/ml/6 days caused no inhibition of the ACTH effects. In concentration of 0.03 μ mole/ml/6 days chloramphenicol resulted in incomplete inhibition of ACTH‐induced formation of mitochondrial vesicular cristae. None of these doses of chloramphenicol affected other ACTH‐induced changes in the fine structure of the cells such as increase of smooth surfaced endoplasmic reticulum, hypertrophy of Golgi apparatus, and development of microvillous processes of plasma membranes. Chloramphenicol also caused no inhibition of the ACTH‐induced accumulation of lipid in the cytoplasm. In cultivated cortical cells of Charles River strain albino rats small groups of annulated lamellae are commonly observed.The present observations suggest that: (1) the development of mitochondrial inner membranes is dependent, at least in part, on mitochondrial protein synthesis; (2) ACTH stimulation of mitochondrial protein synthesis in cortical cells is independent of ACTH‐induced stimulation of nuclear‐DNA‐dependent protein synthesis; (3) doses of chloramphenicol which inhibit specialization of mitochondrial inner membranes of fetal adrenal cortical cells are comparable to those which inhibit protein synthesis in bacteria.
Cytological studies on normal and surviving mast cells in vitro
Authors: Padawer Jacques 
Published: February 2005

AbstractCytological features of rat peritoneal fluid mast cells are studied to advantage with differential interference contrast optics (Nomarski System). These cells are particularly sensitive to handling; they rapidly undergo a variety of cytological changes which, in the literature, repeatedly have been interpreted as reflecting physiological activity related to mast cell secretory function. These interpretations are hereby questioned and, alternately, it is suggested that the changes are agonal ones and that an absorptive function must at least be considered.Some cytological features not detectable with conventional optics are described. The special optics were combined with time‐lapse cinematography and dynamic records were obtained. These support the concept, advanced elsewhere, that sets of mast cell granules are confined within a common membranous sac and that each such set may behave as an independent physiological unit.
The development of the retina of the albino rat
Authors: Braekevelt Charlie R. , Hollenberg Martin J. 
Published: February 2005

AbstractMorphogenesis of the retina of the Sprague‐Dawley albino rat was studied by light microscopy from day 11 of gestation until 225 days after birth. A quantitative analysis during development of retinal volume, thickness of the entire neural retina and thickness of each of the retinal layers, both posteriorly and peripherally, was made. The results indicate that initially a single neuroblastic layer forms and continually thickens by mitosis at its outer border. The retinal layers then form in sequence, moving from the inner retinal border outward and always beginning posteriorly and then spreading peripherally. The transient layer of Chievitz does not appear. All adult layers are present by eight days after birth and each layer thins after reaching its maximal thickness. Total thickness of the retina excluding pigmented epithelium, is greatest on postnatal day 5, but retinal volume only reaches a peak on postnatal days 7 to 12. The nerve fiber, inner plexiform, outer plexiform and bacillary layers all continue to increase in thickness after the ganglion cell and inner and outer nuclear layers reach their maximal width and are beginning to become thinner.
The fine structure of the guinea pig visceral yolk sac placenta
Authors: King Barry F. , Enders Allen C. 
Published: February 2005

AbstractThe structure of the guinea pig visceral yolk sac from 26 days of gestation to term was studied by transmission and scanning electron microscopy. Particular emphasis was placed on the columnar endoderm cells of the villous portion of the yolk sac. The apical cytoplasm of the endoderm cells contained numerous membrane invaginations, endocytic vesicles, dense tubules and large vacuoles which appeared to form an interrelated absorptive system. The saccular invaginations of the apical cell membrane were specialized by the development of both an amorphous extracellular coat and an internal coat. Both the endocytic vesicles and dense tubules were thought to be derived from the saccular invaginations following detachment of the latter from the cell surface — the endocytic vesicles forming by fusion of saccules creating progressively larger structures, and the dense apical tubules forming by a process involving fluid loss from the saccules. Large vacuoles were present deeper in the apical cytoplasm; these probably were formed by fusion of smaller vesicles. The supranuclear cytoplasm contained numerous dense droplets and a Golgi zone. The possible relationships of the droplets to the vacuoles was discussed.
Granulated vesicles in sympathetic nerve endings in the pineal gland: Observations on the effects of pharmacologic agents by electron microscopy
Authors: Duffy Philip E. , Markesbery William R. 
Published: February 2005

AbstractThe effects of pharmacologic agents upon granulated vesicles in the sympathetic nerve endings of the pineal gland were studied electron microscopically. The most common granulated vesicle measures 400 Å and has an eccentric granule (Type IA); a few vesicles are as large as 1000 Å (Type IB). The vesicles also contain fine grains which may be the subunits of which the granules are composed. Reserpine causes many vesicles to become elliptical, raising the possibility of an effect upon the vesicle membrane. Depletion of granules by reserpine is confirmed and fine grains are also depleted. p‐Chlorphenylalanine, which reduces serotonin concentration, causes a reduction in number of granules but leaves fine grains. p‐Chlorphenylalanine followed by pargyline, induces a reduction in number of granules but a considerable number are present suggesting persistence or re‐accumulation of norepinephrine or other catecholamines. Oxypertine and desmethylimipramine (DMI) deplete granulated vesicles but fine grains remain. Another kind of granulated vesicle has a different ultrastructure than the Type IA and IB and measures 1000 Å (Type II). This kind of granulated vesicle is not depleted by reserpine, p‐chlorphenylalanine, oxypertine or desmethylimipramine suggesting that it contains neither catecholamines nor serotonin.