bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some structural and developmental characteristics of cetacean (odontocete) radii. A study of adaptive osteogenesis
Authors: Felts William J. L. , Spurrell Francis A. 
Published: February 2005

AbstractOdontocete radii are short, flattened, longer than the humeri, and lacking in open medullary cavities. Their cross‐section is essentially a semi‐streamlined wedge. End‐on articulation at the elbow is a synchondrosis. In the streamlined, amuscular antebrachium, the radius sustains loadings predominantly in the mediallateral transverse plane as flipper movements (at the shoulder) counter body inertia and water resistance in controlling body attitude.This study treats secondary marine adaptation as reflected in radial development, growth and mechanical organization. Early osteogenesis is similar to that we reported for cetacean humeri, and parallels conditions in the manatee. Later differential growth is analyzed in extenso. Geometry of growth is visualized radiographically in the relationship of endochondral to periosteal bone in the absence of medullary cavitation. Furthermore, the neonatal outline is distinguishable within the porous structure of (only) beluga radii, so that pre‐ and postnatal phases may be differentiated. Radiographs and models demonstrate that as elongation occurs, circumferential increments to growth cartilages are eccentric, i.e., minimal anteriorly, moderate medially and laterally and maximal posteriorly. By this method, the centers of epiphyseal cartilage plates migrate posteriad with time. Periosteal depositions follow the same pattern and are deepest posteriorly. Eccentric growth of the ulna is in the opposite sense. Additionally, proximal growth cartilages of radii tilt posteriad as the bone elongates. Some alterations in growth occur at birth and later. Eccentric growth is an adaptation by which anterior and posterior margins, respectively, of radius and ulna move apart as the bones elongate, and by which functional cross‐sections are maintained in antebrachial bones, singly and as a pair.Bone is concentrated on medial and lateral sides of the radius. This feature, and porosity of the central region, varies with species. Radii, like humeri, thus mimic an engineered box‐beam, and trabecular orientation resembles trajectorial distribution in a loaded beam.Radii have higher absolute densities than do humeri, although both bones have the same range of mineralization as typical mammalian bones. The beluga radius is half again as dense as that of the pilot whale, and thus is intermediate in density between those of most odontocetes and that of the hypothyroid, pachyostotic manatee. The possible evolution of odontocete bones from a more dense dense form, as well as the phylogenetic implications of density changes, are discussed. It is suggested that some of the characteristics of growth and structure, including an apparent periodicity in structural density, may be related to temperature and vascular supply in the high‐area, low‐volume flipper in colder waters.
Development of the flank organ (scent gland) of the Syrian hamster II. Postnatal development
Authors: Thomas Algard F. , Dodge Alice H. , Kirkman Hadley 
Published: February 2005

AbstractIn the first paper of this series, the prenatal development of the flank organ (scent gland) of the Syrian hamster was described. The present paper is concerned with the postnatal development of this organ. The embryology of the organ actually continues into postnatal life, until, during the fifth day, the organ attains the degree of development characteristic of general body skin at birth. Subsequently, an accelerated growth rate results in a conspicuous and characteristic hypertrophy of the gland relative to surrounding integument. During the acquisition of this hypertrophy two opposite developmental gradients are involved, i.e., a series of consecutive centripetal waves of hair cycling and a centrifugal gradient of sebaceous gland development. Maturation of the gland, including changes in its pigmentation and the onset of sexual dimorphism, is discussed in relation to pertinent literature.
Electron microscopy of oligodendrocytes in normal rat cerebrum
Authors: Kruger Lawrence , Maxwell David S. 
Published: February 2005

AbstractElectron microscopic examination of rat cerebral gray and white matter following formaldehyde or glutaraldehyde vascular perfusion reveals distinctive morphological features for identification of oligodendrocytes. These elements are situated as satellites of neurons (perikarya, dendrites and axons), and display a wide range of nuclear and cytoplasmic densities which tend to parallel each other. Cytoplasmic density appears to be an uncertain criterion for neuroglial identification, but oligodendrocytes are recognizable by the following distinctive features: large quantities of free ribosomes or ribosomal rosettes, numerous nuclear pores and light patches of otherwise dense chromatin adjacent to the pores, extensive cytoplasmic microtubules, absence of broad processes seen in other cerebral elements but presence of numerous fine processes which can occasionally be traced to form the outer mesaxon of myelin sheaths, absence of glycogen and fine gliofibrils uniquely present in astrocytes, and the usual presence of thin rims of perinuclear cytoplasm frequently associated with large dilatations of the nuclear cleft. Arguments are adduced for rejecting the identification of “dark” glial elements as microglia. The relation of oligodendrocytes to myelin and the functional significance of the wide spectrum in cytoplasmic density are considered in relation to the synthetic demands of adjacent neurons.
Cytological changes in hepatic and reticuloendothelial cells in rabbit liver following gonadectomy
Authors: Nathaniel Doris R. , Nathaniel Edward J. H. 
Published: February 2005

AbstractMale rabbits of the New Zealand strain were castrated and sacrificed after two, four and six weeks. The animals were maintained on normal diet ad libitum. Alterations in hepatic and reticuloendothelial cells were studied with the electron microscope. The response of the hepatic cell was as follows: The most significant change during the second week was a considerable increase in agranular reticulum which was concentrated along the cell borders as well as within the cells. It was associated with glycogen particles. Accumulation of glycogen was progressive from the second week onward. There was a decrease in the smooth surfaced reticulum as the glycogen content increased. It is suggested that the agranular reticulum is related to glycogen metabolism. An increase in lipids was also present. It is observed that gonadectomy has induced an increase in glycogen and lipid content of the cell. In addition, the nucleus showed a moderate condensation of chromatin along the inner margin. There was a slight increase in the rough surfaced endoplasmic reticulum. Castration also produced changes in the Kupffer cell. This was characterized by the shortening of the cell processes resulting in reduction in cell size. There were fewer inclusions within the cell.
The fine structure of testicular interstitial cells in mice
Authors: Christensen A. Kent , Fawcett Don W. 
Published: February 2005

AbstractThe testicular interstitial cells of mice contain an abundant agranular endoplasmic reticulum occurring as a network of interconnected tubules. Unusual features of the reticulum are occasional extensive whorls of concentric membranes and the occurrence of bundles of parallel double‐walled tubules. The mitochondria have tubular cristae and are occasionally very large.In contrast to the interstitial cells of other species that have been described, the mouse interstitial cells show a segregation of the cytoplasm into areas of dense agranular reticulum and other areas where the agranular reticulum is relatively sparse. The latter areas contain scattered cistenae of granular reticulum, many free ribosomes in clusters, mitochondria, lipid droplets and small granules. The mitochondria and lipid droplets are often encircled by cisternae of the reticulum.Biochemical evidence from other laboratories, taken with the present results, indicates that the membranes of the endoplasmic reticulum in mouse interstitial cells are the site of the enzymes that mediate the synthesis of testosterone from progesterone. There is also an indication that cholesterol biosynthesis is associated with the agranular reticulum. The membranes of the agranular reticulum may also serve as a reservoir for the storage of cholesterol.
Metrial gland and other glycogen containing cells in the mouse uterus following mating and through implantation of the embryo
Authors: Smith Lois Jean 
Published: February 2005

AbstractMouse uteri and embryos from 12 hours to seven days after mating were examined for RNA and glycogen following specific histochemical staining. Because of their greater basophilia, calls present throughout the endometrium which seem to be metrial gland cell precursors could be distinguished as early as two and three‐quarter days. At this time, the uterus is just beginning to undergo “sensitization to decidualization.” By seven days, these precursor cells and metrial gland cells proper have disappeared from all regions of the endometrium except that of the future decidua basalis. Glycogen is present in cells which may be the metrial gland cell precursors, plasma cells and polymorphonuclear leucocytes as well as in the lumens and cells of the uterine glands at three and one‐half days. Between four and one‐fourth and five and one‐half days, glycogen is found in the primary decidual zone. By six days, there is a heavy deposit in the “glycogenic areas.” At seven days, many of the metrial gland cells in the future decidua basalis are PAS‐positive. These findings are discussed and the possible origin of the metrial gland cells from a cell of the lymphocytic series is suggested.
The topographic anatomy of the muscles, nerves, and arteries of the bovine female perineum
Authors: Habel Robert E. 
Published: February 2005

AbstractThe perineal muscles and fasciae are described and illustrated, and the diaphragma urogenitalis, components of m. sphincter urethrae, and m. ischio‐cavernosus are described for the first time in the cow.The nerves of the pudendal plexus are discussed comparatively with the object of suggesting appropriate names based on their homology to the condition in other animals and man. The rami musculares to m. levator ani and m. coccygeus may originate from nn. sacrales 3 et 4, or n. pudendus, or n. rectalis caudalis. The combination of rami musculares with n. rectalis caudalis was formerly called by veterinary anatomists n. hemorrhoidalis medius, a term which should be abandoned because it is not listed in Nomina anatomica, and because it has also been applied to n. splanchnicus pelvinus in the horse. N. pudendus is large and its rami cutanei supply regio femoris caudalis as well as regio perinealis. It also gives rise to n. perinealis profundus, which supplies the genital muscles. The pudendal nerve ends by dividing into ramus mammarius and n. dorsalis clitoridis. There may be one or two nn. rectales caudales. They supply m. sphincter ani externus and adjacent parts of m. levator ani and the genital muscles.The distribution of arteria urogenitalis (vaginalis) and a. pudenda interna are described and illustrated.
Effects of pinealectomy in the newborn female rat
Authors: Wragg Laurence E. 
Published: February 2005

AbstractThat pinealectomy in the rat is followed by ovarian hypertrophy is an assumption which is rather widely accepted and which is fundamental to much contemporary pineal research. Nevertheless an analysis of the alleged supporting literature shows it to be surprisingly weak and limited to animals operated at three to four weeks of age. In several mammals young pineals have been shown to equal or exceed older pineals in certain metabolic activities, but the effect of pineal ablation in the newborn rat is unknown. This report is based on Holtzman female rats pinealectomized at three days, and sacrificed at 60 days of age. The animals comprise a littermate series of eight normal, eight sham operated and eight pinealectomized; and a non littermate series of 18 normal, 17 sham operated, and ten pinealectomized rats. Pinealectomy was proved complete by microscopy of serial sections. Pinealectomized animals in both series did not differ from normals in the weight of the body, ovary, uterus, adrenal, or hypophysis; nor was there a difference in time of vaginal opening, estrous cycle, or 24 hour urinary sodium and potassium output.
The fine structure of the zona glomerulosa and the zona fasciculata of the adrenal cortex of the opossum
Authors: Long John A. , Jones Albert L. 
Published: February 2005

AbstractThe normal fine structure of the zona glomerulosa and the zona fasciculata of the opossum is described, with emphasis on the structure of the smooth surfaced endoplasmic reticulum (SER) and mitochondria. The cells of the zona glomerulosa are characterized by the presence of numerous rod‐shaped mitochondria with shelf‐like cristae, small amounts of tubular SER and moderate amounts of rough surfaced endoplasmic reticulum. The cells of the zona fasciculata possess large quantities of SER, spherical mitochondria with tubular cristae and a few profiles of rough surfaced reticulum. A Golgi apparatus is present in cells of both zones as are coated vesicles, coated invaginations of the plasmalemma, lysosomes and lipid droplets. It is concluded that the tubular SER seen in electron micrographs corresponds closely to the form of this membrane system found in the living cell. The functional significance of the associations observed among lipid droplets, mitochondria and SER are discussed.
The effect of pregnancy on the elastic membranes of mesometrial arteries in the guinea pig
Authors: Albert Ernest N. 
Published: February 2005

AbstractMesometrial arteries were obtained at various stages from adult virgin and primiparous guinea pigs beginning at pregnancy and ending at 40 days post‐partum. The tissues were processed routinely and then stained with hematoxylin and eosin, and various elastic tissue stains. Picro‐indigo‐carmine and Van Gieson were used as counterstains.It was found that during the early stages of pregnancy the subendothelial cells of mesometrial arteries began to proliferate and the internal elastic membrane showed signs of fragmentation. By term the subendothelial cells formed a several layer thick cushion and the elastic fibers were virtually absent. About 22 days post‐partum the subendothelial cells had disappeared and a new internal elastic membrane had formed. These changes are found mainly in the placental mesometrial arteries and to a lesser degree in the peripheral ones. Guinea pigs with unilateral pregnancies exhibited the above changes only on the side of the pregnant horn. It is suggested that the above changes are due to pregnancy and that local hormones elaborated by the placenta may be largely responsible for the alterations in the mesometrial arteries during pregnancy.
The fine structure of compensatory growth in the rat kidney after unilateral nephrectomy
Authors: Anderson Winston A. 
Published: February 2005

AbstractThe structural changes in the nephrons of the rat kidney during compensatory growth were observed for 96 hours following unilateral nephrectomy. Hypertrophy of tubular epithelial cells involves dilation of the cisternae of rough endoplasmic reticulum, proliferation of Golgi membranes and agranular reticulum, and increase in number of cytoplasmic ribosomes. The appearance of absorption droplets and microtubules, that are polarized along the cell axis, coincides with maximal hypertrophy of proximal tubule cells. Premitotic dedifferentiation of these cells involves flattening of the basal infoldings of the plasmalemma, decrease in number and disorientation of mitochondria, loss of apical compartments, and the reduction in number of microvilli. Cilia appear on the apical borders of some cells. Bundles of 30–50 Å filaments occupy the cytoplasm at the base of proximal tubule cells.In distal tubule cells that are undergoing mitosis, numerous mitochondria remain intimately associated with infoldings of the basal plasmalemma. This persistence of the differentiated basal region prevents complete cell division, and binucleate and multinucleate cells arise as a result of failure of cytoplasmic cleavage after normal karyokinesis. During mitosis, the chromosomes and apical vesicles are restricted to organelle‐free masses of cytoplasm that project into the lumen.In collecting tubules, both intercalated and lining cells undergo mitosis during compensatory growth. By 72 hours, a less differentiated cell type, that is active mitotically, appears in the cortical portion of collecting tubules. The number of binucleate epithelial cells increases in the compensating kidney tubules. Unilateral nephrectomy also induces distinct alterations in the fine structure of the glomerulus and the papilla of the contralateral organ.
Some aspects of spermiogenesis in a lizard
Authors: Clark Allen W. 
Published: February 2005

AbstractSpermatids of the American chameleon Anolis carolinensis, have been examined with the electron microscope during the period from the first appearance of caudal sheath microtubules to the stage of differentiation just before the caudal sheath disappears. The caudal sheath microtubles are arranged initially in the form of a helix with a very low pitch. As the condensation of the chromatin and the elongation of the nucleus proceed, the caudal sheath helix unwinds. Shortly before the caudal sheath disappears, the sheath microtubles are oriented parallel to the longitudinal axis of the nucleus and the sheath resembles those found in other vertebrate spermatids. Assuming that the caudal sheath is functionally related in some way to the changes that occur in the nucleus, it is proposed that the unusual arrangement of the caudal sheath in A. carolinensis spermatids is a device to avoid a large excess of microtubules clustered around the nucleus at the end of nuclear elongation.
An ultrastructural study of opaque cytoplasmic inclusions induced by triparanol treatment
Authors: Chen I‐Li , Yates Robert D. 
Published: February 2005

AbstractThe administration of triparanol caused an hypertrophy of smooth membranes and the occurrence of numerous cytoplasmic bodies in smooth muscle fibers and parasympathetic ganglion cells in the myenteric plexus of the hamster ileum. The hypertrophied membranes were more evident in the early stages of treatment when the cytoplasmic bodies were relatively few in number. The cytoplasmic bodies were tentatively divided into four types as follows: whorls of membranes (type I), labyrinthine aggregates of smooth membranes (type II), dense bodies with a reticular internal structure (type III) and crystalline bodies showing a regular lattice pattern (type IV). There were also many intermediate types of cytoplasmic bodies which exhibited more than one characteristic of the types mentioned above. The relative numbers of the cytoplasmic bodies seemed to be increased in the order of type I (or type II), type III, and type IV in proportion to the period of treatment. It is suggested that type IV cytoplasmic bodies are formed through the stages of type I (or type II) and type III, and that types I, II, and III in turn, form from hypertrophied smooth membranes. The formation of crystalline bodies from hypertrophied membranes may represent the inclusion of cytoplasmic organelles into autophagic vacuoles (lysis). After certain degrees of lysis, more resistant components of the hypertrophied membranes remain as residues. These residues, rich in phospholipids, are probably represented as crystalline bodies.
Tissue binding of tritiated norepinephrine in pigmented nuclei of human brain
Authors: Ishii Tsuyoshi , Friede Reinhard L. 
Published: February 2005

AbstractRegional binding of norepinephrine to tissue structures occurs in sections of brain tissue incubated in vitro with tritiated norepinephrine, followed by radioautography. The binding probably represents one of the mechanisms involved in the uptake and storage of catecholamines by nerve cells. Applying this method to a study of human brains showed excessively strong binding of norepinephrine at the surface membranes of pigmented nerve cells in the substantia nigra, nucleus coeruleus, nucleus dorsalis vagi, and others. Such excessive binding was not found in nonpigmented nuclei in the human brain nor in rat brain. The arrangement of sites of binding at the cell membranes strongly suggested synaptic endings. Melanin pigmentation of nerve cells may be related to the amount of catecholamine‐containing synapses at the surface of the neurons.
The fine structure of corpora lutea in ovarian transplants of mice following luteotrophin stimulation
Authors: Crisp Thomas M. , Browning Henry C. 
Published: February 2005

AbstractLutein cells from non‐functional white corpora lutea of ovulation and functional hyperemic corpora following exogenous luteotrophin stimulation were studied in ovarian isotransplants of the mouse with the aid of the light and electron microscope. Luteal tissue of white corpora consisted of small parenchymal cells, some intercellular material and a meager vascular bed. Luteal tissue from hyperemic corpora lutea possessed a rich sinusoidal plexus which supplied the hypertrophied lutein cells. At the fine structural level, lutein cells from functional, hyperemic corpora were distinguished from non‐functional lutein cells in having a reduced lipid content, well‐developed Golgi complex, abundant tubulo‐vesicular elements of agranular and granular endoplasmic reticulum, non‐motile cilia and a more elaborate folding of the cell membrane into microvillous projections bordering the subendothelial space. The functional significance of these morphological changes of luteal tissue in response to luteotrophin was discussed and correlated with recent biochemical findings of steroidogenic tissue. It was concluded that the presence of luteotrophin following luteinization in mouse ovarian transplants results in numerous morphological changes of luteal tissue which are indicative of progesterone synthesis and secretion.
A blood‐brain barrier to peroxidase in capillaries surrounded by perivascular spaces
Authors: Bodenheimer T. S. , Brightman M. W. 
Published: February 2005

AbstractSome investigators have hypothesized that the absence of a blood‐brain barrier in specialized regions of the mammalian central nervous system is related to the occurrence of a pericapillary connective tissue space that can accommodate more substance than the usual narrow extracellular space in the remainder of the cerebral parenchyma. The capillaries of the urodele brain are well suited to test this hypothesis. All of the cerebral capillaries examined electron‐microscopically in Necturus maculosus are surrounded by a collagen‐containing space, about 0.5 m̈ wide, which is delimited by an endothelial and a glial basement membrane. In Ambystoma tigrinum, some capillaries have perivascular spaces whereas others are surrounded by a single basement membrane shared by endothelium and glia and therefore resemble mammalian vessels exhibiting barrier phenomena. In both Necturus and Ambystoma, horseradish peroxidase administered intravenously one‐half to two hours before fixation did not cross the brain capillary endothelium. The bulk of the protein remained in the vessel lumen, although some was incorporated by membrane‐bound inclusions within the endothelium, and none ever reached the perivascular basement membrane, space or parenchyma. The amphibian cerebral endothelium is, like the mammalian endothelium, the locus for the barrier to the entry of peroxidase from blood to parenchyma. Thus, the mere occurrence of a pericapillary space is not necessarily coincident with the absence of a blood‐brain barrier.