bluuebunny/crossref_metadata_2025_split huggingface dataset:
The double hemidesmosome: A new intercellular junction
Authors: Listgarten Max A. 
Published: February 2005

AbstractA new type of intercellular junction was observed between adjacent gingival epithelial cells. The junction appears to be composed of two hemidesmosomes facing one another, with the intervening space occupied by basement lamina material. It is distinctly different from desmosomes or any other intercellular junction described thus far. It is perhaps significant that the combination of two hemidesmosomes into a junction may not result in the creation of a desmosome, but of a rather distinct anatomical structure.
Postnatal growth of the extra‐ and intrafusal fibers in the soleus and medial gastrocnemius muscles of the cat
Authors: Maier Alfred , Eldred Earl 
Published: February 2005

AbstractDevelopment of intrafusal and extrafusal fibers in the soleus and medial gastrocnemius muscles in kittens was studied in sections stained by van Gieson or histochemical procedures. Cross‐sectional areas of intrafusal and extrafusal fibers overlapped extensively in the two weeks following birth, with the means for intrafusal fibers in the medial gastrocnemius muscle being larger than those for the extrafusal fibers. A definite increase in extrafusal fiber size was seen at 20 days and in intrafusal fibers at 29 days. In the one mother cat studied, mean areas for soleus and medial gastrocnemius fibers were 12 and 59 times larger than those for a kitten sacrificed the day after birth, while the intrafusal fiber areas were 3.0 and 4.8 times greater. The equatorial region in nuclear bag fibers showed no significant growth in cross‐sectional area, but almost doubled in length. In a newborn kitten, all extrafusal fibers in the soleus and medial gastrocnemius demonstrated a high level of nicotinamide adenine dinucleotide diaphorase activity, but with the adenosine triphosphatase reaction, fibers had either low or high activity. After one month, soleus fibers with high adenosine triphosphatase activity were scarce, whereas in the medial gastrocnemius fibers with both low and high levels of activity were present. The intrafusal fibers at birth were already morphologically and histochemically differentiated into nuclear chain and bag fibers, and two varieties of the latter could be recognized in slides treated for adenosine triphosphatase activity.
Experimental evidence indicating that the penis of the rat is innervated by short adrenergic neurons
Authors: Dail William G. , Evan Andrew P. 
Published: February 2005

AbstractTo determine if the penis of the rat is supplied by long or short adrenergic neurons, hypogastric and perivascular neurectomies were performed. Reserpine, a drug which depletes the store of norepinephrine from long adrenergic nerves more rapidly than from short adrenergic neurons, has also been used to aid in characterizing this innervation. Hypogastric neurectomy, with or without denervation of the common iliac vessels, had no effect on the density or fluorescence intensity of adrenergic fibers in the rat penis. The long adrenergic fibers to the atria did not fluoresce in reserpine‐treated rats; however, fluorescent adrenergic fibers in the penis and vas deferens remained visible. Reserpine depressed atrial levels of norepinephrine by 75%, while norepinephrine in the penis and vas deferens was reduced only by 32% and 29%, respectively. The absence of any effect of hypogastric neurectomy on the adrenergic fibers of the penis indicates that such fibers arise from neurons distal to the site of lesion of the hypogastric nerves. This result and the similar response of the vas deferens and penis to reserpine strongly suggest that the penis of the rat is supplied by short adrenergic neurons.
Early hypophysial developmental in the chick embryo
Authors: Hammond Warner S. 
Published: February 2005

AbstractThe purpose of this study was to determine the developmental interrelationships existing between the lobes of the hypophysis and the prechordal mesoderm in the chick embryo.Using glass needles, operations were performed in ovo on embryos of three to 13 somites. The operative series involved extirpations of the prospective area or precursors of: (1) anterior lobe alone; (2) posterior lobe alone; (3) posterior lobe and the prechordal mesoderm together; and (4) anterior and posterior lobe precursors and the intervening mesoderm.The results of these experiments indicate that there is a mesodermal‐neural sequence in the inductive process which leads to the development of the anterior lobe. Prechordal mesoderm induces the formation of Rathke's pouch. The latter is then influenced to differentiate through a vascular supply arising from the pial plexus of the infundibular region. Contact of the epithelial and neural rudiments of the hypophysis is not necessary.
The differentiation of white pulp and red pulp in the spleen of human fetuses (72–145 mm crown‐rump length)
Authors: Weiss Leon , Chen Li‐Tsun 
Published: February 2005

AbstractThe development of the white and red pulp in spleen from thirteen human fetuses measuring from 72 mm to 145 mm in crown‐rump length (CRL) was studied using the electron microscope. This period follows the development of the primary vascular reticulum (Weiss, '73).The white pulp appears first as a periarterial sheath with variable numbers of large and medium‐sized lymphocytes, monocytes, macrophages, and some granulocytes and erythrocytes. It is always rich in macrophages. At 90 to 100 mm CRL, reticular cells closely associated with collagen and having a distinctive dark hyaloplasm appeared first in the endothelium and close about blood vessels and then out in the pulp. In the white pulp they became circumferentially arranged about the central artery while in the red pulp they formed a branching reticulum. Small lymphocytes were present in increasing number in the periarterial lymphatic sheath after the development of the circumferential reticulum. The venous sinuses developed and the marginal zone stood out as an erythrocyte‐rich and macrophage‐rich shell of reticulum surrounding the periarterial sheath.
An improved fixation procedure for microtubules and microfilaments in cells of the anterior pituitary gland
Authors: Warchol Jerzy B. , Herbert Damon C. , Rennels Edward G. 
Published: February 2005

AbstractA fixation procedure for the preservation of microtubules and microfilaments in anterior pituitary cells is presented. Small pieces of tissue were fixed at room temperature in a glutaraldehyde solution. The temperature was gradually reduced to 4–5°C before the tissue was post fixed. Post fixation was carried out using several changes of a mixture of cold glutaraldehyde and osmium tetroxide and then osmium tetroxide alone. The osmolarity of both fixing solutions was 400 milliosmoles. The procedure permits a clear visualization of both microtubules and microfilaments within anterior pituitary cells, particularly in regions where they are not ordinarily seen such as within the Golgi apparatus.
An ultrastructural study of normal human mammary epithelial cells in culture
Authors: Russo Jose , Furmanski Philip , Rich Marvin A. 
Published: February 2005

AbstractThe ultrastructure of normal human mammary cells cultured from post‐weaning breast fluids is described. Cells from confluent monolayers in two week old cultures were studied. The epithelial nature of these cells was established by the demonstration of a well developed system of cell‐to‐cell interdigitation and numerous desmosomes. These cells also share with breast epithelial cells in vivo, polarity, with blunt short microvilli on the apical surface and an oriented arrangement of organelles in the basal and apical portions of the cells. The Golgi apparatus, which is the most highly developed organelle, is localized in the apical pole and contains substantial quantities of secretory material in the cisternae and vesicles. A variegated palisade of finely granular material mixed with tonofilaments is seen in the basal portion of the cells; many of these tonofilaments end in the terminal web of the desmosomes.The regular occurrence of these cells in breast fluids during the terminal phases of lactation suggests that their separation is a part of normal breast involution.
Permeability of ovarian follicles and capillaries in mice
Authors: Payer Andrew F. 
Published: February 2005

AbstractThe permeability of ovarian capillaries and follicles in prepubertal and sexually mature (proestrus and metestrus) randomly bred Swiss Albino female mice (SCH:ARS HA ICR strain) was studied by intravenous injection of either ferritin or horseradish peroxidase (HRP), followed by examination with light and electron microscopes. The study revealed that capillaries in the interstitial and perifollicular regions were provided with a continuous endothelium that had constant permeability characteristics irrespective of sexual maturity or phase of the estrous cycle. Horseradish peroxidase left the capillaries primarily through interendothelial cell junctions and was present in all follicles within 30 seconds after administration of the tracer. Ferritin, on the other hand, was absent from endothelial cell junctions, and left the capillaries, at a slower rate than HRP, via cytoplasmic vesicular transport. Both tracers were found in the granulosa cells but rarely in the oocytes. The tracers reached the oocyte through the intercellular spaces between granulosa cells.These findings demonstrate that the follicular apparatus of the mouse is permeable to ferritin and HRP, and that follicular regions such as the basal lamina of the follicle and the zona pellucida do not stop or retard the passage of either tracer.
Cytopathological effects of estradiol on the arcuate nucleus of the female rat. A possible mechanism for pituitary tumorigenesis
Authors: Brawer James R. , Sonnenschein Carlos 
Published: February 2005

AbstractLarge subcutaneous doses (2 mg/21 days) of estradiol valerate (EV) given over several months will induce a prolactin and growth hormone‐secreting pituitary tumor in female rats. The medial basal hypothalami (MBHs) of such EV‐treated animals were examined at different time intervals with light and electron microscopes to determine whether EV affects the MBH and to relate any observed effects to the process of tumorigenesis.The MBHs of extensively treated rats exhibited profound glial and neuronal changes. The filament content of astrocytes was greatly increased and large dense pleomorphic inclusions filled both astrocytic perikarya and processes. Degenerating neuronal elements have been observed in the neuropil of extensively treated animals. Dark cells identified as M cells were seen to engage in phagocytosis and were loaded with dense inclusions. Some neurons in MBH contained large quantities of lipofuscin that was different in appearance from that of normal females of the same age. The glial reaction developed gradually. At earlier stages of EV treatment there were fewer reactive glia and these contained fewer inclusions. Myelin figures often occurred in these early inclusions. Reactive glia in EV‐treated rats did not appear in the preoptic area, dorsomedial nucleus or lateral hypothalamus but were found in ventromedial nucleus. Retired breeders and starvation‐stressed rats resembled normal controls.These pathological changes in MBH may result from a direct effect of EV on the hypothalamus. It is possible that, in addition to its effects on the hypophysis, EV suppresses or injures hypophysiotropic cells in MBH, thus releasing pituitary chromophobes from inhibitory hypothalamic influences. This could result in hypersecretion and neoplasia.
The origin of the follicular capillaries in the human spleen
Authors: Snook Theodore 
Published: February 2005

AbstractThe major arteries which supply the follicular capillaries in the human spleen do not arise as they do in most mammals as lateral or radial branches from the central artery but come from penicillar arteries which penetrate the marginal zone and enter the follicle at various points around its circumference. Such arteries may have a very short course through the red pulp or they may pursue very long courses.Upon entering the follicle, these arteries branch a number of times, the branches remaining together in a tight array of parallel arterioles along with capillaries formed from them, the whole bundle being enveloped by a reticular fiber sheath. There is thus formed an arteriolar‐capillary bundle. The whole bundle may branch. From the sides, especially from its central end, arterioles and capillaries radiate out to all parts of the follicle to terminate in the marginal zone or in the follicle itself.
A morphological and histochemical study of the developing tongue musculature in the mouse: Its relationship to palatal closure
Authors: Holt Thomas M. 
Published: February 2005

AbstractSome question exists concerning the ability of the embryonic tongue to undergo reflex movements at the time of palatal closure (15.5 days of development). Functional motor endplates are prerequisite for such movements to occur. Light and ultrastructural cytochemical methods were employed to elucidate the morphology of neuromuscular relationships in the developing mouse tongue. The A/Jax mice used in the experiments demonstrated a 12–20% incidence (seasonal variation) of spontaneous cleft palate, allowing a correlation between normal and teratological processes. Organized myofibrils were first seen in tongues of normal and spontaneous cleft lip‐cleft palate (SCL‐CP) specimens at 14.5 days of development. The thiocholine technique of Karnovsky and Roots was used to demonstrate acetylcholinesterase (AChE) activity at the light microscope level. The Lewis and Schute method was used for ultrastructural localization of this enzyme. Tissues from normal and SCL‐CP specimens from 12.5 to 20.5 days of gestation failed to show differences in amounts or distribution of AChE activity. AChE activity was seen as early as 14 day's gestation. Electron microscopic studies demonstrated reaction product in the endoplasmic reticulum and nuclear envelope of developing myoblasts. AChE activity at the developing neuromuscular junction and the occurrence of myofilaments preceded palatal closure by several days.Based on these morphological and histochemical findings the tongue of normal and SCL‐CP embryos appears capable of responding to a neurogenic stimulus at the time of palatal closure. The findings suggest that the tongue of animals exhibiting a spontaneous cleft palate is not actively involved in the etiology of this condition.
Capillary innervation in the mammalian central nervous system: An electron microscopic demonstration
Authors: Rennels Marshall L. , Nelson Erland 
Published: February 2005

AbstractCapillaries in the cat hypothalamus receive axon terminals which are comparable to neurovascular junctions in cerebral and systemic arteries and arterioles. The innervation of capillaries in the central nervous system may be derived from central neurons, in contrast to cerebral arterial vessels, which are supplied by the peripheral autonomic nervous system.
A light and electron microscopic study on the embryonic development of the rat carotid body
Authors: Kondo Hisatake 
Published: February 2005

AbstractThe embryonic development of the rat carotid body was studied with electron microscopy. In the 11 mm embryo a cell aggregation consisting of undifferentiated cells and unmyelinated nerve fibers appears on the anterior wall of the third branchial artery. Granule‐containing cells appear in the 12 mm embryo and continue to increase in number as the cellular aggregation increases in size and becomes separated from the wall of the third branchial artery. Synapse formation and the appearance of fenestrated capillaries occur almost simultaneously at the 17 mm stage. There are two types of synapses, one with membrane densification and vesicles clustered inside the nerve endings, the other with dense material and vesicles inside the granule‐containing cells. At the 20 mm stage the undifferentiated cells send enveloping cytoplasmic processes toward adjacent granule‐containing cells and the carotid body anlage displays rudimentary lobules.
Scanning electron microscopy of normal rat liver: The surface structure of its cells and tissue components
Authors: Grisham J. W. , Nopanitaya W. , Compagno J. , Nägel A. E. H. 
Published: February 2005

AbstractScanning electron microscopy (SEM) allows the surface ultrastructure of intrahepatic cells and other tissue components of liver to be delineated. Excellent depth of focus of the SEM makes it possible to visualize surfaces of intact cells in their native configurations. This report details the surface characteristics and inter‐relationships of hepatocytes and hepatic plates, sinusoidal endothelial cells and sinusoids, presumed Kupffer cells, vessels, bile ducts, connective tissue, and the capsule of rat liver. Hepatocytes present three structurally distinctive faces – the intercellular face containing flat surfaces and bile canaliculus, the sinusoidal face, and the connective tissue face which abuts portal tracts and hepatic veins. Sinusoidal endothelium is penetrated by large (1 to 3 μm) and small (0.1 μm) fenestrae, the latter occurring in clusters of up to 50. The width of bile canaliculi and distribution of large fenestrae vary proximodistally along hepatic plate or sinusoid. The cells of portal bile ductules contain microvilli located in linear rows and sparse cilia. Endothelium of hepatic artery and of portal vein is sparsely fenestrated.
Periodic fibrillar material in intracellular vesicles and in electron‐dense bodies in chondrocytes of rat costal and tracheal cartilage at various ages
Authors: Dearden L. C. 
Published: February 2005

AbstractThe occurrence of intracellular fibrillar material (frequently banded) has been studied in normal costal and tracheal chondrocytes of rats at various ages ranging from 1 to 90 days. The study methods have included digestion with collagenase, electron histochemical techniques and routine electron microscopy.Banded fibrillar material has been observed intracellularly in vesicles or in electron‐dense bodies in perichondrial and subperichondrial chondrocytes from rats of all ages. These fibrils and extracellular collagen fibrils are partially and equally degradable by collagenase, they are positive after staining with phosphotungstic acid or with silver nitrate methenamine, and their lucency corresponds with that of collagen when they are stained only with lead citrate.They have not been observed in intracellular clefts. They, therefore, seem to be formed intracellularly and to be exocytosed subsequently.Large vesicles and electron‐dense bodies seem to be derived from Golgi saccules. A mechanism whereby banded intracellular fibrils could be formed from tropocollagen molecules is postulated. The frequency of occurrence and the diameter of intracellular fibrils seems to increase with increasing age.
Morphological diversity of oocytes released from the adult mouse ovary
Authors: Swartz William J. , Schuetz Allen W. 
Published: February 2005

AbstractThis study was designed to classify and differentiate the population of oocytes released from the mouse ovary by mechanical means. Liberated oocytes were classified on the basis of their number, size and by the nature of the attachment of follicle cells to these oocytes. Microscopical examination of oocytes mechanically released from the ovaries revealed three distinct morphological classifications of oocytes: (1) those completely devoid of follicle cells, (2) those encased in follicle cells and (3) those in the process of degeneration. Oocytes ranged in size from approximately 30μ to 119μ. Those oocytes surrounded by follicle cells could be further subdivided into two groups depending on whether the follicle cells could be mechanically removed from the oocyte. These data demonstrate that the adult ovary contains a variety of classes of oocytes which differ in size and in the extent to which the follicle cells are attached to the oocytes. It is suggested that the metabolic activities and meiotic potentials of the various oocyte populations differ and as a result, care should be employed to insure a uniform population of oocytes when conducting further studies with mechanically liberated oocytes.
The cytochemical localization of adenyl cyclase activity in rat sublingual gland
Authors: Kim S. K. , Han S. S. 
Published: February 2005

AbstractAdenyl cyclase activity in mucous acinar cells and serous demilune cells of the rat sublingual gland was localized cytochemically. After incubation with adenylyl‐imidodiphosphate (AMP‐PNP) as substrate, deposits of reaction product are found along the cell membranes bordering the secretory surfaces of serous demilune cells. These are the membranes which participate directly in secretion by fusing with the granule membranes. The granule membranes of the demilune cells do not reveal reaction product, but the membranes of the granules which are fused with and become part of the cell membrane do show deposits. Thus, it appears that the cell membranes which fuse with granule membranes during secretion are associated with a high level of adenyl cyclase activity. In support of this, the luminal membranes of the mucous acinar cells which do not fuse with granule membranes during secretion are not associated with detectable amounts of adenyl cyclase activity.
The programming of canalization in fetal lungs of man and monkey
Authors: Boyden Edward A. 
Published: February 2005

AbstractIn the monkey lung (Macacus nemestrina) canalization of all bronchopulmonary segments begins simultaneously at the peripheral future‐alveolar‐duct portions of each segment and then continues progressively centralwards. Its simultaneous appearance in all segments of a human lung of the 17th postovulatory week (19th postmenstrual week) has now been confirmed (cf. Boyden, '74). The mode of canalization, as seen under the light microscope, is here demonstrated.
Light and electron microscopic observations on hydrocortisone‐induced cleft palate in hamsters
Authors: Shah Ravindra M. , Travill Anthony A. 
Published: February 2005

AbstractPalatal histogenesis in hydrocortisone‐treated hamster fetuses was studied by both light and electron microscopy. At an early stage in the hydrocortisone‐affected fetuses, when the palatal shelves hung vertically on either side of the tongue, necrotic changes could be seen in some of the basal epithelial cells which lay adjacent to the fragmented basal lamina. The normal looking cells lay on an intact basal lamina and were attached to the contiguous necrotic cells by desmosomes. With horizontal reorientation of the palatal shelves and their approach to the midline, cellular necrosis and fragmentation of the basal lamina increased. When compared with normal cells, the hydrocortisone‐affected ones were seen to be lighter, to contain fewer ribosomes and no lysosomes. At a later stage, when midline palatal fusion was lacking, the epithelium underwent stratification and keratinization while the necrotic debris was removed by mesenchymal macrophages. It appears that the normal process of protein synthesis is inhibited following hydrocortisone administration and that this, in turn, during palatogenesis, disrupts normal cellular differentiation and the integrity of the basal lamina, which are associated with the production of a cleft palate.