bluuebunny/crossref_metadata_2025_split huggingface dataset:
The postnatal growth of the rat lung III. Morphology
Authors: Burri Peter H. 
Published: February 2005

AbstractIn order to investigate the postnatal growth of the gas exchange apparatus, the lungs of rats aged 1, 4, 7, 10, 13, and 21 days were fixed by intra‐tracheal instillation of glutaraldehyde. The analysis and interpretation of the morphological changes observed by light and electron microscopy were based on the results of previous morphometric and autoradiographic studies performed on the same material.The newborn rat has no alveoli, but breathes with smooth walled air channels and saccules, which correspond to the prospective alveolar ducts and alveolar sacs, respectively. The bulk of alveoli are formed between days 4 and 13 by a rapid outgrowth of secondary septa from the primary septa present at birth. The arrangement of elastic fibers during this period suggests that these may play a role in septal outgrowth. Based on ultrastructural observations a model is described for the capillarisation of the secondary septa. Some evidence is given that alveoli may also be formed by outpouchings in the walls of terminal bronchioles.Primary and secondary septa have initially an immature appearance. They both show an apparently double capillary network, whereas the mature interalveolar septum is just wide enough to accommodate a single capillary. Possible mechanisms for this structural transformation which occurs within three weeks after birth are discussed.
Ultrastructural development of the chorioallantoic placental barrier in the bat Macrotus waterhousii
Authors: Bodley H. Daniel 
Published: February 2005

AbstractThe phyllostomid bat, Macrotus waterhousii, undergoes delayed development. Implantation occurs early in the nine‐month gestation, but the blastocyst remains relatively dormant until the sixth month when a chorioallantoic, hemodichorial placenta forms and a two and one‐half to three‐month growth pattern occurs leading to parturition.The barrier in the chorioallantoic placenta at first includes maternal capillary endothelium, but during the early part of the rapid growth phase the endothelium is replaced by blocks of syncytial trophoblast which penetrate the basal lamina. The basal lamina then apparently thickens and remains as the intrasyncytial lamina. Thus, the definitive barrier for maternal nutrients consists in order of passage of syncytial blocks, intrasyncytial lamina, syncytiotrophoblast, cytotrophoblast, fetal basal lamina and capillary endothelium.
A quantitative study of the satellite cell population in postnatal mouse lumbrical muscle
Authors: Schultz Edward 
Published: February 2005

AbstractThe satellite cell population in mouse lumbrical muscle is quantitated at ages 7, 14, 21 and 30 days. Satellite cell nuclei comprise nearly 30% of the nuclei within the fiber basal lamina in the youngest animals studied. Growth is accompanied by a rapid decrease in the percentage of satellite cell nuclei. This is not accounted for by the increase in myonuclei, but rather there is an absolute decrease in the number of satellite cells. This loss in satellite cells occurs in spite of their high rate of division and is explained by a high percentage incorporation of the daughter cells of satellite divisions. It is further suggested that the percent incorporation of available cells decreases with age.
Hormonal influences on the morphogenesis of the preputial gland of embryonic mice
Authors: Cunha Gerald R. 
Published: February 2005

AbstractFetal preputial glands from 14‐ to 17‐day old mouse embryos undergo comparable growth, branching, and display similar degrees of cytodifferentiation when cultured in vitro on medium lacking hormones, on this medium in the presence of either of the fetal gonads, and on medium supplemented with testosterone dipropionate. Conversely, morphogenesis of these anlagen is markedly suppressed by estrogen and an anti‐androgen, Cyproterone acetate. These observations demonstrate that acquisition of androgen‐sensitivity is a late event in the morphogenesis of the preputial gland and correlate with the developmental properties of preputial mesenchyme as demonstrated in earlier studies on the epithelio‐mesenchymal interaction.
Ultrastructure of the cilia of thymic cysts in “nude” mice
Authors: Cordier Andre C. 
Published: February 2005

AbstractThe ciliary ultrastructure is studied in the ciliated cells of the thymic cysts of the “nude” mouse. The cilium is made up of two segments: the intracellular basal body and the extracellular cilium shaft.The basal body extends in a rootlet and demonstrates three annexes: basal foot, anchoring system and tonofibrillar web. The rootlet, composed of one central and nine peripheral chambers, is closely and constantly associated with smooth endoplasmic reticulum. The classical periodicity of the basal foot can be explained by its internal structure. The anchoring system binds the upper part of the basal body to the cell membrane. The cilium shaft is divided into four segments: implantation base, proximal segment, intermediate segment and tip. The details of particular structures in the implantation base and in the proximal segment are given on transverse and longitudinal sections. In the intermediate part, a peculiar desmosome‐like structure, binds some doublets with the ciliary membrane. At the tip level, A tubules end up in an opaque plate and membranes are covered with several intricated cristae.
Vein size in intact and hysterectomized mice during the estrous cycle and pregnancy
Authors: Forbes Thomas R. , Taku Elaine 
Published: February 2005

AbstractThe diameters of the ovarian, uterine, and femoral veins and the inferior vena cava were measured during stages of the estrous cycle in intact and hysterectomized mice and at intervals during pregnancy in mice with embryos in both uterine horns or in only the left horn. At metestrus I vein sizes were the least and were not significantly different in intact and hysterectomized mice. Ovarian and uterine veins showed the same or increased diameters at other stages of the cycle; veins enlarged progressively during pregnancy in intact mice. Non‐gravid uterine horns showed little size increase as compared to gravid horns. Increases in vein diameter appeared to be correlated with local production of reproductive hormones.Evidence for transuterine migration of embryos was observed in 21 of 53 mice in which one uterine tube had been ligated or one ovary had been removed.
Electron microscopy of the intestine of the african lungfish, Protopterus aethiopicus
Authors: Purkerson M. L. , Jarvis J. U. M. , Luse S. A. , Dempsey E. W. 
Published: February 2005

AbstractElectron microscopic observations are reported on the intestine of the African lungfish, Protopterus aethiopicus. The lungfish has a spiral valve rather than a true stomach. Segments of mucosa from this area reveal, by transmission microscopy, that most cells have distinct striated borders with parallel microvilli. Fibrils within the core of the microvilli extend deeply into the cytoplasm. Microvilli on the surface of goblet cells are less regularly arranged than those of absorptive cells. Interspersed among the cells with striated borders are cells, similar in cytologic appearance except that they are covered with tufts of kinetocilia. By transmission electron microscopy, abnormal cilia having one complete complement of microtubules plus incomplete sets from other cilia which share some of the peripheral doublets of the complete cilium are enclosed by a single membrane. Cilia are usual in the intestine of many lower forms but ordinarily absent in higher vertebrates. Their functional significance in this primitive fish is unknown.
The implantation chamber, blastocyst and blastocyst imprint of the rat: A scanning electron microscope study
Authors: Enders Allen C. 
Published: February 2005

AbstractSplitting the uterus longitudinally through implantation sites makes it possible to obtain access to blastocysts and implantation chambers during stages of implantation of the blastocyst in the rat. On the afternoon of day 5 of pregnancy, blastocysts lie in a shallow antimesometrial depression and tend to fall free of the uterus when the chamber is opened. On day 6, blastocysts are oriented in a mesometrial‐antimesometrial plane, occupy a distinct implantation chamber, and tend to adhere to one side or the other of the uterus, leaving an imprint on the contralateral side. After about noon of day 6, some of the blastocysts split in half laterally, and by day 7 all blastocysts which are exposed are split. In addition to demonstrating increased adhesion of blastocyst to uterine epithelium, the procedure clearly shows the progressive elongation of the implantation chamber. The embryonic cell mass is specifically oriented on day 6, and is clasped but not distorted, whereas the abembryonic trophoblast is slightly compressed and indented by the uterine epithelium. The microvilli of the uterine epithelium within the imprint become progressively flattened when compared to the microvilli of the implantation chamber outside of the imprint. The method provides a means of gaining direct access to the surface of uterine epithelium precisely where it has been in association with the blastocyst not only for scanning electron microscopy but also for studies of the properties of the surface constituents.
The systemic arterial pattern of the guinea pig: The abdomen
Authors: Shively Michael J. , Stump John E. 
Published: February 2005

AbstractThe systemic arterial pattern of the guinea pig was studied to determine the arrangement of the major arterial trunks and their branches. Fiftynine specimens were examined by dissection, angiography or corrosion casting. The arterial arrangement was found to resemble a typical mammalian pattern, although some exceptions were noted. For example, the guinea pig usually has a single vessel, the celiacomesenteric trunk, instead of separate celiac and cranial mesenteric arteries. The celiac components of this vascular axis were found to originate in four different patterns. Also, the renal arteries were found to be single or double on either side with double origins more frequent.
Rapid freezing of deep cerebral structures for electron microscopy
Authors: van Harreveld A. , Fifkova Eva 
Published: February 2005

AbstractA method is described for the investigation of deep cerebral structures by freeze‐substitution. The head of a mouse is sectioned in a guillotinelike apparatus. The exposed surface is subjected to freeze‐substitution. Electron micrographs prepared from this material exhibit under a layer of sheared tissue, a layer of tissue comparable with that observed previously in micrographs of the cerebral and cerebellar cortices subjected to freeze‐substitution of their natural surfaces. By varying the plane in which the head is sectioned any structure in the brain can be made accessible to freeze‐substitution.
Development of beaks of Rana pipiens larvae
Authors: Kaung Hue‐Lee Cheng 
Published: February 2005

AbstractRana pipiens larval beaks consist of column cells, sheath cells and basal cells which supply cells to column and sheath. Each column consists of disk‐like precone cells, cone cells and keratinized cone cells; they are cells in different stages of the process of keratinization.Beaks first appear externally at embryonic stage 24. Epidermal cells align at the tip of the jaw at stage 21. They increase in number and change in shape. Keratinization starts at stage 23. By stage 24, the apical column cells are keratinized and the histological organization is set for the whole larval period.During the larval period, the numbers of column cells increase until stages VIII or IX, stay relatively constant during mid‐larval stages, and decrease at late larval stages. The beak is completely shed at stage XX. The widening of the beaks goes on during the entire larval period. Along the cutting edge of the jaw the booth spikes increase in number and in individual width as the animal grows older and larger.Thyroid hormone causes a premature reduction of the column cell number and a precocious beak loss. The loss of beak at metamorphic climax is a thyroid dependent event.
Development of the tibial tuberosity
Authors: Ogden John A. , Hempton Robert F. , Southwick Wayne O. 
Published: February 2005

AbstractThe tibial tuberosity develops by a concomitant, and juxtaposed, outgrowth of hyaline cartilage and ingrowth of fibrovascular tissue. During the fetal period this hyaline cartilage outgrowth is progressively distally displaced to become situated adjacent to the anterior portion of the tibial metaphysis. About four to six months post‐natally a growth plate develops under the tibial tuberosity. This growth plate shows structural adaptations that permit accommodation of large tensile stresses. The growth plate of the tibial tuberosity has three distinct regions — (a) a zone of endochondral bone formation, (b) a zone of intramembranous bone formation through fibrocartilage, and (c) a zone of intramembranous bone formation through fibrous tissue.
Skeletal effects of magnesium deficiency in normal, ovariectomized, and estrogen‐treated rats
Authors: Bogoroch Rita , Belanger Leonard F. 
Published: February 2005

AbstractThe effects of magnesium deficiency in ovariectomized and estrogen‐treated rats were examined in histological sections of bones and various soft tissues. The changes observed in the femora of intact rats deprived of magnesium for three weeks were: 1. a general increase in diaphyseal thickness, 2. the presence of localized fibrous or bony‐like masses in subperiosteal and metaphyseal sites, and 3. the occurrence, although rare, of endosteal hyperplasia. In ovariectomized, magnesium‐deprived animals, the incidence and location of fibrous masses were similar to that in the femora of magnesium‐deficient intact rats; however, no increase in diaphyseal thickness was noted. Daily injections of 25 μg estradiol caused a reduction of the frequency of skeletal hyperplasia from 80% to 20%, as well as a reduction in femoral diaphyseal thickness. Estradiol hormone administration also brought about a marked alleviation of the dermal and neural manifestations of magnesium deficiency, but, at the same time, caused an exacerbation of renal calcinosis.
Post‐natal development of the median eminence of the guinea pig
Authors: Silverman Ann‐Judith , Desnoyers Patricia 
Published: February 2005

AbstractThe ultrastructure of the median eminence of neonatal (newborn, 1‐, 3‐, 5‐, and 10‐day old) and adult guinea pigs was studied to determine the dynamic changes occurring in this structure during early life. At birth the portal vasculature consists of the Mantelplexus and a few, non‐fenestrated capillary loops. The number of ansae and the degree of fenestration increase rapidly after birth. The abundance of cytoplasmic and ciliary projections into the ventricular recess and the large numbers of organelles indicate that the ependymal cells are more active in the neonatal period than in the adult male. Moreover, the ependymal endfeet cover most of the surface area of the primary portal plexus during this time. The neuronal layers of the median eminence are difficult to distinguish at birth due to the lack of myelinated fibers in the zona interna. Significant myelination appears on day 3 but is not complete until day 10. There is a progressive increase in the numbers of Herring bodies and large neurosecretory granules (1,500‐1,700 Å) during this same time period. In the zona externa, few nerve terminals abut on the perivascular space until day 3. Increases in numbers of granules per axon profile were noted for each day after birth. Despite the relatively long gestation period of the guinea pig (68‐72 days), the morphologic appearance of the median eminence at birth suggests that the neurovascular link controlling anterior pituitary function is not yet complete.
The normal human thymic vasculature: An ultrastructural study
Authors: Bearman Robert M. , Bensch Klaus G. , Levine Gerald D. 
Published: February 2005

AbstractElectron microscopy of the normal human thymus demonstrates a characteristic vascular‐parenchymal relationship. The vascular lumen is always separated from the thymic parenchyma by: the endothelial cell cytoplasm, a muscular coat in arterioles and veins, the vascular basal lamina, a perivascular space containing collagen fiber and cells, the epithelial‐reticular cell basal lamina and the epithelial‐reticular cell cytoplasm. The width of this perivascular space is proportional to the size of the vessel it surrounds; it is wide around the vessels in the septa and at the cortical‐medullary junction, but narrow around capillaries. While many cells are present in this space around the larger vessels, only collagen is observed around the capillaries. Lymphocytes are the predominant cell type in the space; however, plasma cells, eosinophils, histiocytes, polymorphonuclear leukocytes, mast cells and unidentified granulated cells are also seen.The vascular complex described above may function as a blood‐thymus barrier, as the initial site of exposure of the lymphocytes to circulating antigen and as the route of emigration of lymphocytes from the thymus.
Smooth muscle in lymph node capsule and trabeculae
Authors: Folse Dean S. , Beathard Gerald A , Granholm Norman A. 
Published: February 2005

AbstractThis study focuses on the confusion in existing literature concerning the presence of smooth muscle in the capsule and trabeculae of lymphnodes. Human and bovine nodes from several anatomical areas and several individuals of each species were examined by conventional light, electron and fluorescence microscopy. Smooth muscle cells, independent of blood vessels, were demonstrated in the trabeculae and capsules of lymph nodes of both species examined by all three techniques. The need for further study on the function of these cells is indicated.
The fine structure of the interhemal membrane of the rat chorioallantoic placenta during prolonged pregnancy
Authors: Jollie William P. 
Published: February 2005

AbstractIn placentas from viable rat fetuses which surgically had been retained beyond term in lactating animals for as long as four days, the fine structue of much of the interhemal membrane was quite like that of full‐term placentas. Moreover, contrary to what has been reported previously (Jollie, 1964a), in retained placentas which were autopsied at term there were few changes in the four cytoplasmic layers of the membrane which could be interpreted as degenerative. With prolongation of the placenta beyond normal delivery the number of pericytes which were associated with the allantoic endothelium increased; the basal lamina separating the endothelium from trophoblast III progressively became more focally split; and the apposed plasma membranes between this latter layer and trophoblast II appeared to dissociate. Trophoblast II became regionally divided in its cytoplasmic organization, its more superficial zone becoming highly infolded and/or vacuolar. As a consequence, the intertrophoblastic space between layers I and II became more extensive and complex. Within this space, a flocculent material appeared; and there was ultrastructural evidence of massive pinocytosis from the space by trophoblast II. With increased prolongation of gestation, a variety of lysosome‐like inclusions appeared within this layer of the membrane.
Ultrastructure of baboon parotid gland
Authors: Tandler Bernard , Erlandson Robert A. 
Published: February 2005

AbstractThe parotid gland of the olive baboon, Papio anubis, was examined by electron microscopy. The acini are all serous in nature, and consist of pyramidal cells with abundant secretory granules of varying size. These granules consist of a dense matrix in which a denser spherule or lenticular body is present. Granules linked by a short isthmus are observed in the apical cytoplasm, and granules in the process of discharging their contents to the acinar lumen may be connected to the luminal plasma membrane by a neck‐like protrusion. Intercalated duct cells contain granules reminiscent of those found in the rat submandibular acinar cells. The striated ducts consist of tall cells interloked in a complex fashion near their bases, with numerous vertically‐oriented mitochondria lodged in their basal crenulations. Small vesicles whose contents vary in density are present in the apical cytoplasm as are large deposits of lipofuscin. The striated duct cells display a proclivity for ballooning into the duct lumen. Excretory ducts consist of simple to pseudostratified columnar epithelium, and lack basal striations or apical blebs.
Growth of the second metacarpal according to chronological age and skeletal maturation
Authors: Kimura Kunihiko 
Published: February 2005

AbstractIn relation to chronological age and skeletal maturation, the growth of the second metacarpal is discussed based on radiographs of the right hand and wrist in 499 male and 424 female Japanese aged 1 to 18 years. When plotted against age, bone length and width present the general growth pattern of Scammon, the adolescent spurt occurring at about 13 years in the males and 11 years in the females, and the mean values are significantly larger in the males than in the females at age 15 years for length, and age 13 years for width, and later. The growth curves of both sexes are almost parallel to each other for bone length plotted against skeletal maturation. Bone width progresses in parallel in males and females until about adolescence, whereafter there is a more rapid increase in growth in the males than in the females. The mean values for length and width are almost always significantly greater in the males than in the females. The width/length index decreases rapidly until a certain period, the minimum value being at about ten years or a maturity corresponding to that age, and then increase slightly again to reach an equilibrium state on the basis of both age and skeletal maturation. At any given age, the mean values are always greater in the males than in the females. However, according to skeletal maturation, the sex differences are steadily significant at and after the skeletal maturity corresponding to about 12 years in the males and 10 years in the females.
A macroscopic study of the brain of Bison bison bison, the American Plains Buffalo
Authors: Harper Jon W. , Maser Jack D. 
Published: February 2005

AbstractThe macroscopic anatomy of the brain of the American Plains Buffalo (Bison bison bison) is detailed herein for the first time. Many features vary significantly from most previously described ungulate species including its large size, fissural pattern of the cerebral hemispheres and well developed insular cortex. The midbrain, particularly the tectum, is outstanding: the superior colliculi appear to be the largest reported for any mammal and occupy most of the dorsal midbrain by surface area and volume estimates. The cerebellum is small relative to the total brain volume, a peculiarity reported elsewhere for other ungulates. Morphometric criteria further indicate the brain of bison is highly specialized. Drawing from various lines of evidence, it is suggested that the anatomical uniqueness of the present day bison brain may represent a vestige of the past, remaining largely unchanged over a broad expanse of geologic time.