bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intracellular channels as a route for protein passage in the capillary endothelium of the shark brain
Authors: Hashimoto Paulo H. 
Published: February 2005

AbstractCapillaries in the area postrema and other brain regions at the level of the obex were examined in Japanese sharks under the electron microscope with or without intravascular injection of horse‐radish peroxidase and histochemical incubation. The postremal capillaries were characterized by a relatively wide perivascular space filled with connective tissue elements including fine fibrils about 100 Å in diameter, and by endothelial fenestration; however, the space and fenestration were apparently less extensive than in rats and cats (Hashimoto, '66; Rivera‐Pomar, '66; Hashimoto and Hama, '68). In other brain regions, the capillary endothelium showed peroxidase‐filled intracellular channels that connected the luminal surface with the basement membrane soon after peroxidase injection. Many of the adjoining endothelial cells were linked by tight junctions. Perivascular astrocytic processes had long, tight contacts of about 125 Å in overall thickness. Discussion was focused on a possible endothelial route for passage of so‐called barrier‐free substances in the central nervous system of higher vertebrates.
Histochemical and electron microscopic observations on the sperm receptacles in the garter snake oviduct
Authors: Hoffman Loren H. , Wimsatt William A. 
Published: February 2005

AbstractThe sperm storage receptacles in the oviduct of the garter snake, Thamnophis sirtalis, were studied using histological, histochemical, and electron microscopic techniques. The receptacles are located in the posterior infundibulum and are readily distinguished from other structures within the oviduct. The luminal epithelium consists of secretory cells and ciliated cells. The latter cell type also lines the ducts leading to the receptacles. The distribution of lipids, carbohydrates, and several enzymes (succinic dehydrogenase, acid and alkaline phosphatases, nonspecific esterase, lipase, sorbitol dehydrogenase) in the infundibulum is described.At the electron microscopic level sperm heads are seen to be closely associated with the surface of receptacle cells, often indenting the luminal plasma membrane. The possibility of a “Sertoli cell‐like” relationship is discussed. Formation of cytoplasmic vacuoles in receptacle cells is temporally associated with ovulation and may be part of a mechanism for sperm release from receptacle cells. No contractile elements were observed immediately around the receptacles.Evidence is presented which suggests that free fructose and glucose are produced by the oviduct, possibly to be utilized for sperm metabolism at the time of ovulation and sperm release.
The effect of lithium carbonate on the structure of the rat kidney
Authors: Evan Andrew P. , Ollerich Dwayne A. 
Published: February 2005

AbstractFemale Sprague‐Dawley rats were used to study effects of lithium carbonate on the ultrastructure of the rat kidney. Experimental rats received daily intraperitoneal injections of lithium carbonate in dosages of 10, 30 or 100 mg/kg/day. These animals were killed on day 12 to 60. Control rats were either non‐injected or injected with either sodium chloride or sodium carbonate. Kidneys from control rats showed no abnormal changes. The 10 and 30 mg/kg lithium carbonate dosages caused progressive mitochondrial swelling, dilatation of cisternae of rough endoplasmic reticulum and occasional swelling of apical cytoplasm in tubular cells localized in the distal portion of the nephron. The 100 mg/kg lithium dosage produced damage in all portions of the nephron. However, the most severe damage, consisting of mitochondrial swelling, dilatation of the rough endoplasmic reticulum, apical cytoplasmic rarefaction and liquefaction, karyolysis and karyorrhexis was noted in the distal convoluted tubules and collecting ducts. The present study demonstrated that low dosages of lithium carbonate do affect the structure of the rat kidney.
The fine structure of the interstitial tissue of the rat prostate
Authors: Flickinger Charles J. 
Published: February 2005

AbstractThe structure of the interstitial tissue of the rat prostate has been studied using the light and electron microscopes in an attempt to determine the role of the fibromuscular stroma in the normal functioning of the gland. Smooth muscle cells and fibroblasts are the most numerous cell types. They are accompanied by macrophages, mast cells, and undifferentiated cells of low electron density. Smooth muscle cells have cytoplasmic protrusions that extend into corresponding depressions in adjacent muscle cells, and, at these points, the intercellular space is narrowed to 150–2000 Å. Smooth muscle cells and fibroblasts are arranged in parallel in septa between adjacent epithelial alveoli and form a sheath around each alveolus. Proceeding peripherally from the epithelium into the interstitial tissue, this sheath is composed of a layer of one or two highly flattened fibroblasts and a parallel layer of smooth muscle cells, followed subsequently by additional layers of fibroblasts and smooth muscle that merge into the remainder of the interstitial tissue. Most of the capillaries have an uninterrupted endothelium, but in some regions endothelial fenestrations are present. Unmyelinated axons contain aggregations of small granular and agranular vesicles. Vesicles are found in axons at distances up to several thousand angstroms from muscle cells and in axons that approach to within 150–200 Å of smooth muscle cells. In some cases an axon lies in a deep depression in the surface of a muscle cell. The type of innervation and variety of intercellular contact between muscle cells is discussed in relation to probable physiological characteristics of the tissue.
Placental development in the mongolian gerbil (Meriones unguiculatus). I. Early development to the time of chorio‐allantoic contact
Authors: Fischer Theodore V. , Floyd Alton D. 
Published: February 2005

AbstractEarly gerbil development was studied from days 4 through 12 of gestation. Implantation occurs on day 8 in a shallow antimesometrial implantation crypt. The proamniotic cavity forms from an invagination of basal trophoblast and a folding together of the rim of the cup thus produced. The approximation of this rim gives rise to the ectoplacental cone. The further development and expansion of the ectoplacental cone is much like the rat. Amniogenesis is by folding into the proamniotic cavity. Between large glycogen‐filled decidual cells occur many PAS‐positive eosinophilic granular cells. A massive subplacental gland forms from proliferating uterine epithelium within the decidua basalis. Epithelial proliferation begins shortly after implantation, and soon short thick cellular processes extend from the antimesometrial side of the lumen whereas long branching cords penetrate the decidua basalis mesometrially. The function of this structure is unknown.
Structure and carbohydrate histochemistry of postnatal canine salivary glands
Authors: Reifel Conrad W. , Travill Anthony A. 
Published: February 2005

AbstractStructural changes in secretory units of developing canine salivary glands have been correlated with their histochemically demonstrable carbohydrate content. At birth, three and eight weeks, and six months, secretory cells and duct systems of parotid, submandibular, sublingual and zygomatic glands of mongrel puppies were examined for morphology and localization of sulfomucin, sialomucin, neutral polysaccharide and glycogen. Combining structural and histochemical criteria a classification was formulated to discriminate between mucous, serous, and seromucous cells. Within the first six months of life changes occur in the proportion of these cells in individual salivary glands. Structurally distinct typical and atypical mucous cells contained acidic carbohydrates, usually sulfomucin. In sublingual glands of more mature dogs, however, sialomucin was the predominant constituent in atypical mucous cells. Serous acinar cells containing neutral polysaccharide occurred only in these glands. Seromucous acinar cells secreting acidic carbohydrates, usually sialomucins, were recognized in parotid and zygomatic glands. Demilunes composed of sialomucin‐producing seromucous cells and neutral polysaccharide‐producing serous cells were observed in submandibular and zygomatic glands, respectively. From this investigation it appears that the structural and carbohydrate profile of developing canine salivary glands is distinctive to the particular age examined.
The ultrastructure of the thyrotropic cell during thyrotropin rebound in the adenohypophysis of the rat
Authors: Rosa Charles G. , D'Angelo Savino A. 
Published: February 2005

AbstractAdenohypophyses of rats were studied ultrastructurally to ascertain the morphologic changes that occur in thyrotropic cells during the pituitary TSH Rebound Phenomenon. Rats were maintained on propylthiouracil (PTU) for 43–147 days and their adenohypophyses studied three to nine days after discontinuance of goitrogen treatment. TSH rebound was also induced in chronically hypothyroid rats by single intravenous injections of 0.8, 4, 20 and 200 μg of thyroxine. Pituitaries were studied from animals sacrificed 6–24 hours after thyroxine injection. Thyrotrophs of euthyroid rats were characterized ultrastructurally by the presence of numerous peripherally‐located, small secretory granules (storage phase) and by highly dilated cisternae of rough endoplasmic reticulum (secretory phase). The thyrotropic cells in PTU‐treated rats were sparsely granulated, displayed enlarged mitochondria with much loss of cristae and contained extensively dilated rough endoplasmic reticulum and expanded Golgi membranes.Marked repletion of granules, both intracisternal and cytoplasmic, was seen during TSH rebound in the pituitary. It was observed in some thyrotrophs as early as three days after goitrogen withdrawal and was enhanced further at the 6‐ and 9‐day intervals. Granule repletion increased progressively with doses of thyroxine up to 20 μg and assayable thyrotropin in pituitary glands increased 500–700% over normal. Effects with the 20 μg dose could be detected as early as six hours. With higher doses of thyroxine, granule repletion in thyrotrophs was inhibited and mitcohondrial hypertrophy was largely reversed.The electron microscopic findings reveal close correlation with previously published data on thyrotropin assays of the rat pituitary. They support the concept that the degree of cytoplasmic granulation in thyrotropic cells is quantitatively related to assayable stores of thyrotropin in the anterior pituitary gland.
A study on division of primordial germ cells in the early chick embryo
Authors: Swartz William J. , Domm L. V. 
Published: February 2005

AbstractThe purpose was to determine the sites, times and frequency of mitotic activity in primordial germ cells in the white Leghorn chick embryo during the period of migration. Colchicine was employed to facilitate the identification of dividing germ cells in embryos ranging in age from 18 hours to five days of incubation (stages 3–27). An increase in the number of germ cells was observed during the period of migration, due primarily to proliferation of intraembryonic cells, since no significant increase in the number of extra‐embryonic germ cells was seen during this period. The number of germ cells during this period ranged from 43 at 18 hours to 2211 at 120 hours. Two periods of intense proliferation were observed, the first between 48 and 72, the second between 96 and 120 hours. This coincided with a simultaneous increase in the number of germ cells during these periods. Dividing germ cells were present in the extraembryonic blood vessels anterior, lateral and posterior to the embryo at 28, 48 and 72 hours and within the intra‐embryonic circulatory network at 48, 72, 96 and 120 hours. At 72, 96 and 120 hours, dividing germ cells were numerous in the tissues of the dorsal mesentery adjacent to the developing gonads and within the gonads. Dividing germ cells were also located in head mesenchyme, limb buds and mesenchyme surrounding the notochord‐neural tube complex. Dividing germ cells were found in the chick embryo throughout the entire migratory period.
The demonstration of cilia in canine macula densa cells
Authors: Sottiurai Vikrom , Malvin Richard L. 
Published: February 2005

AbstractAlthough the presence of cilia in mammalian epithelia is common, the finding of cilia in the macula densa cell of the kidney has never been reported. In this paper are reported electron microscopic observations of cilia in canine macula densa cells. The cilia observed have the classic 9+2 configuration. The centriole, basal body, foot process, ciliary rootlet and the substructure of the latter also were observed.
Cytochalasin‐B: Effects on cytokinesis, glycogen and 3H‐D‐glucose incorporation
Authors: Sanger J. W. , Holtzer H. 
Published: February 2005

AbstractTime‐lapse pictures of He La cells grown in a medium with low concentrations of Cytochalasin‐B revealed that during division furrowing proceeds normally until the mid‐body forms. Only then was the centripetal contraction of the furrow blocked. In time the contracted furrow relaxed, resulting in a binucleated cell. Cytochalasin‐B exerted a profound depression on the level of glycogen in the cells and on the incorporation of 3H‐D‐glucose into glycogen, glycoprotein and mucopolysaccharides. These observations suggest that sensitivity to the drug may be due more to interference with glucose uptake and utilization than to disruption of putative contractile microfilaments in the cell cortex.
Circadian rhythms in mitotic activity and 3H‐thymidine uptake in the duodenum: Effect of isoproterenol on the mitotic rhythm
Authors: Scheving Lawrence E. , Burns E. Robert , Pauly John E. 
Published: February 2005

AbstractMitotic activity in the duodenum of the rat and mouse exhibits a circadian periodicity with a peak in the rat between 1200 and 1500 hours and a sustained trough between 1800 and 0600. Scintillation counts revealed a similar rhythm in the total uptake of 3H‐thymidine by the rat duodenum with a sustained but fluctuating crest occurring between 0800 and 1800 and a trough between 1900 and 0100. In the mouse the peak mitotic activity occurred at 0900 and the trough at 1700. Isoproterenol completely abolishes the rhythm in mitosis in mouse duodenum, when injected exactly 28 hours previous to sacrifice. The results are discussed in relation to reports that deny a circadian rhythm in mitotic activity in the duodenum.
Ultrastructural studies of the effects of various agents on the motor neurons of the spinal cord
Authors: Yates Robert D. , Yates Jane C. 
Published: February 2005

AbstractIn a previous study, morphological alterations of motor neurons were noted following an injection of strychnine. These changes consisted of dilated endoplasmic reticulum and the presence of intramitochondrial granules. In the current ultrastructural study rats were given either dihydrobetaerythroidine, metrazol, curare, botulinum toxin, fluoroacetate, fluorocitrate, Bungarus multicinctus venom, Naja naja venom, tetrodotoxin or potassium cyanide while other animals were given first one of these agents and then strychnine. Alterations in the endoplasmic reticulum and the presence of intramitochondrial granules were noted only when strychnine was given alone or in combination with one of the other agents.These results indicate that convulsive activity, release of transmitter substance at the neuromuscular junction, exhaustion of the transmitter substances from the motor neurons during excessive discharge, interruption of oxidative phosphorylation or the direct action of strychnine on the neuronal membrane does not result in changes such as are seen after an injection of strychnine alone. Tentatively, we propose that strychnine alters neuronal membrane permeability with consequent disruption of the ionic equilibrium of the neuron, which is reflected as dilated endoplasmic reticulum, and the presence of intramitochondrial granules.
Innervation of pulmonary alveoli of the mouse lung: An electron microscopic study
Authors: Hung Kuen‐Shan , Hertweck M. Sue , Hardy John D. , Loosli Clayton G. 
Published: February 2005

AbstractThe nerve supply to the alveolar ducts and alveoli of mouse lungs was studied with the electron microscope. In the alveolar ducts, nerve bundles consisting of as many as nine unmyelinated axons surrounded by connective tissue fibers were usually located in the interstitium surrounding the openings of the alveoli. In the alveolar walls, nerve bundles consisting of as many as five unmyelinated axons were located in the interstitium between pneumocytes and the capillaries. The unmyelinated axons contained neurotubules and some mitochondria, and were partially or completely surrounded by Schwann cells. Two distinct types of enlarged nerve endings were identified. The first type contained many small mitochondria and was either associated with the type I pneumocyte or located alone in the interstitium. The second type was packed with numerous large dense‐core vesicles and was in close contact with the type II pneumocyte. It is suggested that the first type of ending is sensory and the second type is motor in function.
Ultrastructure of developing germ cells in the fetal rabbit testis
Authors: Gondos Bernard , Conner Lucy A. 
Published: February 2005

AbstractTesticular differentiation, as evidenced by the appearance of a distinct tunica albuginea and formation of plate‐like aggregates of germ cells and mesenchymal cells, occurs at 16 days in the rabbit fetus. The germ cells at this stage of development are isolated large, round to oval cells that are easily distinguished from the smaller elongated mesenchymal elements surrounding them. The germ cell nuclei have a smooth spherical contour and a prominent eccentric nucleolus. Cytoplasmic organelles are sparse, consisting of scattered polyribosomes and spherical or ovoid mitochondria distributed singly in the cell. At 18 days, the cell groups form into distinct cords of germ cells and supporting cells, the earliest stage of seminiferous tubule formation. Between 22 and 25 days, proliferating germ cells show increasing condensation of nuclear chromatin and increased nucleolar complexity. The cytoplasm contains groups of mitochondria, dense polyribosomal complexes, lipid aggregates, scattered smooth vesicles and prominent Golgi complexes. Intercellular bridges appear between germ cells on day 22 and increase in number on succeeding days. During the last week of fetal development, germ cells become aligned in rows at the periphery of the primitive tubules. Their arrangement at this time resembles that of spermatogonia in the adult testis. However, the fetal “prespermatogonia” lack some of the characteristic ultrastructural features of adult spermatogonia.
Oocyte structure and early vitellogenesis in the trout, Salmo gairdneri
Authors: Beams H. W. , Kessel R. G. 
Published: February 2005

AbstractLight and electron microscopic studies have been made on young oocytes of the trout; i.e., during previtelline and early stages of vitellogenesis. Balbiani's basophilic body has been followed from its origin in the youngest oocyte to its disappearance at the beginning of vitellogenesis. It assumes the form of a duplex body composed of a non‐basophilic component (idiosome) and a highly basophilic portion, the pallial substance. Electron micrographs reveal the Balbiani body to be a dense, finely granular substance apparently unrelated to the Golgi apparatus or mitochondria. Its role in oogenesis is not clear, but probably constitutes an essential precursor substance (perhaps RNA) necessary for oocyte growth and vitellogenesis.At given periods in early oocyte growth, an extensively developed system of endoplasmic reticulum is formed and the cisternae contain numerous granules. These intracisternal granules probably represent precursor elements for a specialized type of yolk substance. The granules collect in dilated regions of the smooth‐surfaced cisternae where the latter undergo anastomosis. Here the granules undergo transformation into a finely granular particle. Older and more vitellogenetic oocytes have not been included in this study.
Location of large core synaptic vesicles in the dorsal gray matter of the cat and dog spinal cord
Authors: Duncan Donald , Morales Ricardo 
Published: February 2005

AbstractCross sections of aldehyde‐perfused, Epon‐embedded cat and dog spinal cord examined with an electron microscope display numerous synaptic vesicles with electron‐opaque cores along the medial and lateral margins of the dorsal gray matter (laminae I, II, III). The cored vesicles, 750 – 1500 A in diameter are located in synaptic sacs and in small unmyelinated axons. They occur in small numbers throughout the apical gray matter but are much more numerous in a narrow band immediately adjacent to the white matter. Their numbers and location should be of value in studies on the nature and origin of this type of synaptic vesicle.
An in vivo and in vitro autoradiographic investigation of growth in synchondrosal cartilage
Authors: Servoss Joel M. 
Published: February 2005

AbstractThe inherent growth potential of synchondrosal cartilage has been studied as follows. Sixty CD‐1 mice were injected with 3H‐thymidine on their first day of life. Thirty of these were sacrificed one hour after injection, and their cranial bases were removed and placed in an organ culture system. The explants were removed from culture at six‐hour intervals for one day and then every 24 hours for five more days. The remaining animals, which comprise the in vivo series, were sacrificed by decapitation at corresponding times. In order to detect cell movements, the spheno‐occipital synchondroses were divided into five zones, and labeled cell counts were done for each zone. The labeled cartilage cells spread apart with growth as new cells were formed in the central zone and moved toward the outer zones The labeled cells moving from the central resting zone to the outer hypertrophic zones were comparable in absolute number and in rate of movement in both the in vivo and in vitro cartilages. The fact that synchondroses grown in culture retained their capacity for growth without benefit of neighboring tissues seems to indicate that the spheno‐occipital synchondrosis possesses an inherent potential for growth and is not merely reactive or adaptive in nature.
Synaptic ultrastructure in the tangential nucleus of the goldfish (Carassius auratus)
Authors: Hinojosa Raúl 
Published: February 2005

AbstractThe synaptic ultrastructure in the tangential nucleus of the goldfish was studied with the electron microscope. The nucleus consists of cells measuring 30–40 μ in diameter receiving complex innervation from eighth nerve fibers and boutons. Two types of synaptic contacts by the eighth nerve, terminal and en passant, were recognized. Three varieties of the terminal type were described: calyciform, trilobated, and club endings. The three varieties of the terminal type, as well as the synapses en passant, showed gap junctions in their synaptic membrane complex. The morphological characteristics of these endings suggested electrical transmission.The boutons synapsing on the tangential cells were of two types: terminal and en passant. Three varieties of boutons terminaux were described. One of these was classified as a mixed synapse. The morphological characteristics of the synaptic vesicles of the other two varieties suggested that the boutons could be inhibitory or excitatory.