bluuebunny/crossref_metadata_2025_split huggingface dataset:
The fine structure of the monkey submandibular gland with a special reference to intra‐acinar nerve endings
Authors: Kagayama Manabu 
Published: February 2005

AbstractThe secretory terminations of monkey submandibular gland were studied by electron microscopy. The acini are composed of two types of secretory cells which are presumably serous and mucous in type. Myoepithelial cells are present also in the acini. The peri‐acinar connective tissue contains many unmyelinated nerve fibers. In some portions, the axons contain many synaptic vesicles of various types. These nerve endings partially lose their Schwann cell investment and reach the acinar basement membrane. In peri‐acinar connective tissue two types of nerve endings may be recognized. They are thought to be adrenergic and cholinergic in type. On the other hand, only one type of nerve ending (cholinergic) is observed within the acini. The intra‐acinar nerve endings are not surrounded by Schwann cell cytoplasm and make direct contact with plasma membranes of the myoepithelial and mucous cells, with a space about 200 Å wide intervening between the nerve and terminal cell. No nerve endings occur in the interspaces between the serous cells. Also, the ultrastructure of the secretory and myoepithelial cells is described.
Secretory processes in follicular cells of the bat thyroid. II. The occurrence of organelle‐associated intercellular junctions during late hibernation
Authors: Nunez Eladio A. 
Published: February 2005

AbstractThe fine structure of bat thyroid follicular cells was examined throughout the late hibernation period (January 17 to April 1), when thyroid gland function undergoes marked increase. The follicular cells during this period are squamous and possess few microvilli, an inconspicuous Golgi complex, scanty rough‐surfaced endoplasmic reticulum and a small number of mitochondria. The cells also exhibit conspicuous membrane‐limited dense bodies and atypical intercellular contacts. The atypical junctional complexes are characterized by a localized dense thickening of the apposed lateral plasma membranes which run parallel to each other for approximately 1 μ. The two dense membranes are separated by an intercellular space 75 Å wide and there is close apposition of rough‐surfaced endoplasmic reticulum and mitochondria. The occurrence of these unusual junctional complexes during late hibernation is discussed in relation to the known increase in thyroid function which occurs at this time.
Regeneration of rabbit olfactory epithelium
Authors: Mulvaney Bruce D. , Heist Herbert E. 
Published: February 2005

AbstractEpithelial regeneration was determined with light and electron microscopy after preferential chemical destruction of olfactory epithelium in rabbits. Regeneration of either olfactory epithelium, ciliated columnar epithelium or a mixture of the two occurred. Previously observed interspecies variation in olfactory regenerative capability is therefore also an intraspecies variable. The ducts or glands of Bowman appeared to furnish the cells for either type of epithelial regeneration. Well differentiated olfactory cells re‐appeared as early as eight days after destruction with olfactory regeneration being essentially completed 30 days after destruction.
Influence of bile and pancreatic secretions on the size of the intestinal villi in the rat
Authors: Altmann Gabriel G. 
Published: February 2005

AbstractAlong the rat small intestine, the size of the villi gradually decreases from a maximum in the duodenum to less than half of this size in the terminal ileum. In previous work, various villus enlarging and reducing factors present in the intestinal chyme were found to control villus size. A villus enlarging factor which appeared to reach the intestine through the duodenal papilla was presently investigated.Transplants of duodenal papilla, together with a small segment of the duodenum, were made to isolated ileal segments and to the lower ileum. At both sites, the transplants elicited a marked villus enlargement within a month. A previous finding was that villus size decreased in isolated duodenal segments unless the duodenal papilla was present.In the next experiments, the bile‐drainage was diverted from the duodenal papilla by implanting the bile duct into an isolated ileal segment which in turn was joined to the colon. The duodenal papilla which now transmitted only pancreatic secretions was then transplanted to the ileum. The bile caused only moderate villus enlargement in the ileal segments whereas marked villus enlargement took place in the ileum receiving the pancreatic secretions.It was concluded that a villus enlarging influence reached the intestine through the duodenal papilla. The pancreatic secretions appeared to play a major role in this influence.
A morphological study of the development of the human liver. II. Establishment of liver parenchyma, extrahepatic ducts and associated venous channels
Authors: Severn Charles B. 
Published: February 2005

AbstractThe establishment of liver parenchyma, extrahepatic ducts and associated venous channels were examined in serial sections of 100 human embryos representative of Horizons XI through XVII.The liver parenchyma first begins to develop from the cephalic end of the hepatic diverticulum in embryos between the 20‐ and 25‐somite stage. The parenchyma develops as cords from the walls of the diverticulum which anastomose around isolated endothelium‐lined spaces (blood islands) in the septum transversum. As growth and anastomoses of the parenchymal cords continue, the isolated endothelium‐lined spaces form an interconnecting capillary bed which interdigitates with the developing parenchymal cords. The larger omphalomesenteric veins develop simultaneously with the parenchyma and are continuous with the smaller venous channels which interdigitate with the parenchymal cords. These larger developing veins become surrounded by the developing parenchymal cords. As the parenchymal cords branch from the cephalic end of the diverticulum, that portion of the diverticulum becomes reduced to a small tubular structure, the common hepatic duct, which is always continuous with the parenchyma. As the cephalic portion of the original diverticulum is reduced in size, there is a localized outgrowth from the ventral wall of the caudal end of the original diverticulum. This localized outgrowth becomes the cystic duct and gallbladder. The remainder of the caudal segment of the diverticulum elongates to become the common bile duct. The ventral pancreas develops as a localized outgrowth from the dorsal wall of the common bile duct.
Electron microscopic observations on the contribution of the ultimobranchial bodies to thyroid histogenesis in the rat
Authors: Calvert R. 
Published: February 2005

AbstractThe fine structure of ultimobranchial bodies in the rat has been studied from the fifteenth to the twentieth day of gestation. At 15 days, the ultimobranchial bodies were still separated from the median thyroid primordium by connective tissue. Their lumina were filled with cellular debris and their thick walls were made up of one type of cell in which rough‐surfaced endoplasmic reticulum was scanty. Early in the sixteenth day, cell cords from the median thyroid primordium came in direct contact with the ultimobranchial bodies; no basal lamina separated them. At 17 days the walls of the ultimobranchial bodies were composed of C cells, glycogen‐rich cells and cells that were poor in rough‐surfaced membranes and glycogen. At 18 days three types of cells were present in cell cords in direct contact with the ultimobranchial bodies: C cells, glycogen‐rich cells and follicular cells. The first two cell types had migrated from the ultimobranchial bodies while the follicular cells had originated from the median primordium. In the same cell cords, follicular cells containing glycogen granules were interpreted as being an intermediate stage between glycogen‐rich cells and true follicular cells. In follicular cells of the isthmus region, which presumably originate from the median primordium alone, glycogen granules were not observed after the fifteenth day of development. It is concluded that C cells and few follicular cells are of ultimobranchial origin.
A fine structural study of the highly active thyroid follicular cell of the African basenji dog
Authors: Nunez Eladio A. , Belshaw Bruce B. , Gershon Michael D. 
Published: February 2005

AbstractThe highly active thyroid gland of the basenji dog has been studied. The follicular cell of the basenji thyroid is unusual in that colloid droplets may be found in the apical cytoplasm of normal cells. Their appearance does not require administration of exogenous thyrotrophin. The colloid droplets appear to have been taken in by invagination of the apical plasma membrane forming a small bay at the cell‐colloid interface. Apparent fusion of adjacent plasma membranes subsequently eliminates the mouth of the bay, completing endocytosis of the droplet. Basenji follicular cells are also distinguished by a dense accumulation of two varieties of lysosomes, basal associations of lip d droplets and mitochondria with unusual cristae and specialized junctions between cells of adjacent follicles. It is suggested that these unique structural modifications reflect adaptations for the perpetually active state of the basenji thyroid.
Regional differences in postweaning growth by choroid plexuses as affected by dietary salt deficiencies
Authors: Quay W. B. 
Published: February 2005

AbstractA diet low in K and Na given to postweaning rats of the Berkeley S1 strain led in two experiments to a greater than normal relative weight of the choroid plexus of ventricle IV (= C.P. IV) to weight of the whole brain in both sexes. This effect did not occur in the choroid plexuses of ventricles I + II (= C.P. I + II) and III (= C.P. III), which were lower than normal in absolute weights and unchanged in ratios with whole brain weights after the low K and Na diet. Quantitative microscopic tissue analyses of the choroid plexuses following one of the experiments failed to demonstrate significant differences in relative tissue composition or cellular structure after this diet. Other evidence, and data on normal postnatal growth of choroid plexuses, suggests that the unequal apparent responses of the different choroid plexus regions to the diet are related to differences in their durations and rates of growth after weaning rather than to a necessarily specific cellular response in the choroid plexus of ventricle IV to internal consequences of dietary restriction in K and Na.
Comparative studies on the proteolysis of fixed gelatin membranes by mammalian sperm acrosomes
Authors: Gaddum‐Rosse P. , Blandau R. J. 
Published: February 2005

AbstractThe acrosomes of mammalian spermatozoa contain a proteolytic enzyme which may be of importance for fertilization. The release and activity of the enzyme can be visualized directly when the spermatozoa are applied to fixed gelatin membranes. The purpose of this study was to determine the pattern of enzyme release from the spermatozoa of a variety of mammalian species. Thin, transparent membranes of pure gelatin were prepared on microscope slides and fixed in glutaraldehyde. Spermatozoa were applied to the membranes and their proteolytic behavior observed under dark‐medium phase objectives at 37°C. In all the species examined (rabbit, bull, hamster, rat, guinea pig and man) extensive depolymerization of the gelatin substrate occurred around the sperm heads. With the exception of human spermatozoa, the onset of proteolysis was clearly identified with the posterior half of the acrosome. In the case of human spermatozoa, no such distinction could be made. It is suggested that the proteolytic enzyme of most mammalian spermatozoa is located in the posterior segment of the acrosome.
Oxyhemoglobin affinity in the armadillo
Authors: Dementi Patricia L. , Burke Jack D. 
Published: February 2005

AbstractOxygen‐hemoglobin affinity curves determined spectrophotometrically at 26± 1° C on phosphate‐buffered hemoglobin solutions of 9 armadillos yielded a mean P50 value of 10.1 mm Hg at pH 7.4 and 18.4 mm Hg at pH 6.8. For the 18 curves determined simultaneously at both pH's the mean calculated magnitude of the Bohr effect was ϕ = − 0.43. These values indicate a moderately low P50 (high oxyhemoglobin affinity) and small Bohr effect, consistent with the low metabolic rate of Dasypus novemcinctus. Indicative of increased tolerance to blood acid by‐products, a small value would be advantageous to the armadillo in its adaptation to intensive anerobic energy production. A major and a more slowly moving minor hemoglobin fraction was confirmed by vertical starch‐gel electrophoresis using borate buffer at pH 8.7 and benzidine staining. Transmission curves on oxyhemoglobin had an α peak at 578 mμ and a β peak at 543 mμ.
Effects of halothane on the ultrastructure of rat liver cells
Authors: Ross William T. , Cardell Robert R. 
Published: February 2005

AbstractThe objective was to study the effects of halothane, a volatile anesthetic, on hepatic metabolism of a second volatile anesthetic, methoxyflurane, and to correlate these biochemical findings with hepatic morphological changes. Microsomal fractions isolated from rats treated with halothane and from control animals were assayed for their capacity to dechlorinate methoxyflurane. Microsomes from halothane‐treated rats demonstrated about 2.6 times the capacity to dechlorinate methoxyflurane as microsomes from control animals. Electron microscopy showed that liver cells from halothane‐treated animals, when compared with hepatocytes from control rats, had increased amounts of smooth endoplasmic reticulum, an increased number of lipid droplets, and more microbodies per cell. Rough endoplasmic reticulum and glycogen were decreased by halothane treatment. We interpret these results to mean that halothane induces the rough endoplasmic reticulum to synthesize enzymes required for the biotransformation of methoxyflurane. It is suggested that these enzymes are placed in membranes of the rough endoplasmic reticulum. This organelle is converted to smooth endoplasmic reticulum and here the biotransforming enzymes function to dechlorinate methoxyflurane.
Prenatal development of the ductus epididymidis in the rhesus monkey. The effects of fetal castration
Authors: Alexander Nancy J. 
Published: February 2005

AbstractAfter formation of the epididymis, the cuboidal epithelial cells of the ductus epididymidis undergo little cytodifferentiation in the fetal rhesus monkey. However, from 130 days of fetal life until birth, the cells undergo a period of differentiation that proceeds in an anterio‐posterior direction along the duct. Concurrently epithelial cells of the ductus efferens and caput epididymidis transform from a cuboidal condition with no surface modifications to cells similar to those of adults. Over 50% of the cells become ciliated and the remainder develop surface modifications resembling those in adult nonciliated cells. The epithelial cells lining the ducts of the corpus epididymidis, and in some cases those of the cauda epididymidis, develop stereocilia.Castration of the fetus between the 106th and 112th day of gestation prevents differentiation of the epithelium of the epididymis. Administration of medroxy‐progesterone, a drug with androgenic properties, to the mother of a castrated fetus results in normal differentiation of epithelial cells lining the fetal caput epididymidis. These studies indicate that fetal differentiation of the epithelial cells of the epididymis depends on the secretion of androgen by the fetal testes. The androgen level drops at birth, and concomitantly the epithelial cells of the male reproductive tract return to an undifferentiated state until puberty.
Ultrastructural observations on mitosis in myocardial cells of the rat embryo
Authors: Chacko Kurien 
Published: February 2005

AbstractCardiac tissue from rat embryos at 10, 11, 12, 13, 14, 15, days of gestation and newborn rats were processed and studied under the electron microscope. A unique observation in the developing myocardium is detection of the simulataneous occurrence of mitosis and synthesis of muscle‐specific contractile proteins (actin and myosin filaments) in the same cells. Mitotic cells containing sites of myofilaments are discernible throughout the gestational period covered in this investigation, including the myocardium of new born. Unlike skeletal muscle, in the myocardium of rat embryos the onset of fibrillogenesis is not correlated with cessation of mitotic activity.
The effect of shedding on skin homografts in the garter snake, thamnophis sirtalis
Authors: Terebey N. 
Published: February 2005

AbstractAll skin homografts shed a layer of keratin or an outer epidermal generation when shedding appeared in the recipient. Skin homografts did not express the timing of the shedding cycle found in the donor animal. It was concluded that the timing of shedding is determined by the recipient but not by the skin. The response of skin homografts was not affected by age, sex or the stage between sheddings when grafts were taken from donors. A review of mammalian work shows that skin homografts in the rat show the timing of the hair growth cycle found in the donor although eventually these homografts also become synchronized with the recipient. Less complex mechanisms seem to be involved in the shedding cycle in garter snakes than in the hair‐growth cycle which evolved in mammals.
Scanning electron microscopy of the lateral ventricles of sheep
Authors: Kozlowski Gerald P. , Scott David E. , Murphy Judith A. 
Published: February 2005

AbstractThe lateral ventricles and choroid plexuses of an adult and near‐term sheep fetus were examined with scanning electron microscopy. The predominant surface structure of the ependymal cells were cilia arranged in clumps with evidence of metachronic activity. Topographical variations of the ependymal surface are described and discussed according to their role in transport of cerebrospinal fluid and their relation to underlying nervous tissue.
Ultrastructure of the interstitium in the rabbit kidney
Authors: Bulger Ruth Ellen , Nagle Ray B. 
Published: February 2005

AbstractKidneys from six male New Zealand white rabbits were fixed by perfusion, and the interstitium of all zones was studied by light and electron microscopy. The volume and amount of the basic components varied not only between cortex and medulla, but within each zone itself. Two main cell types were found in the cortical interstitium, the first appeared to be morphologically identical with a fibroblast, although it contained frequent surface depressions. The second cell type was of the mononuclear series, the most frequent of which was characterized by abundant free ribosomes and was frequently wrapped by processes of fibroblasts. Although collagenous fibrils, basement membrane‐like material, and flocculent electron‐dense material have previously been described in the interstitium of other animal species, this paper describes the presence and distribution of microfibrils approximately 150 Å in diameter with electron‐lucent cores throughout the entire kidney interstitium and discusses the distribution of globular deposits which may represent glycosaminoglycans in the various zones of the kidney.
Cytology of eccrine sweat glands in the opossum
Authors: Fortney James A. 
Published: February 2005

AbstractEccrine sweat glands occur only within the glabrous foot and toe‐pad skin of the Virginia opossum, Didelphis virginiana, Kerr. Two distinct types of secretory cells are found in the terminal portion of this gland, i.e., dark and clear cells. Thin myoepithelial cells are located between these secretory cells and the outer basal lamina. Histochemical techniques indicate that dark cells contain dense proteinaceous secretory granules. This observation is supported by measuring the refractive index (n) of dark cell granules by interference microscopy. The interferometric properties and certain staining characteristics (acidophilia) displayed by these secretory granules are comparable to those of the stratum corneum layer of opossum glabrous skin. Ultrastructurally, dark cells contain electron‐opaque secretory granules and parallel arrays of granular endoplasmic reticulum, resembling those of other protein‐secreting cells. Subcutaneous injections of pilocarpine nitrate elicit a secretory response from dark cells consisting of granule extrusion, reduction in cell size, and extreme vacuolization of the cell cytoplasm.
Changes in muscle morphology and histochemistry produced by denervation, 3,3′‐iminodipropionitrile and epineurial vinblastine
Authors: Wuerker Raymond B. , Bodley H. Daniel 
Published: February 2005

AbstractThree types of muscle fibers are present in the normal triceps surae of the rat; they are designated large, pale; intermediate; and small, dark. Following denervation, these fibers undergo changes which cause the muscles to become less distinctive with respect to fiber types. The fibers atrophy preferentially, round up, lose their angularity, and lose their staining capacity for succinic dehydrogenase, mitochondrial adenosine triphosphatase, and the periodic acid‐Schiff procedure. Intraperitoneally administered 3,3′‐iminodipropionitrile produces no change in muscle histochemical characteristics. Injection of vinblastine into the epineurium of the sciatic nerve results in a histochemical picture similar to that of denervation, while destruction of the nerve occurs distal to the site of injection.
Structure and function of the hamster corpus luteum during the estrous cycle
Authors: Leavitt W. W. , Basom C. R. , Bagwell J. N. , Blaha G. C. 
Published: February 2005

AbstractLuteal cell structure and function were studied by electron microscopy in conjunction with measurement of progesterone production by corpora lutea which were isolated and incubated in vitro on successive days of the four‐day hamster estrous cycle. Granulosal cells were primarily responsible for the formation of the corpus luteum. Agranular endoplasmic reticulum and lipid droplets developed during luteinization of granulosal cells on the first post‐ovulation day (day 1). Luteal cell hypertrophy on day 2 resulted from dilation of tubular agranular endoplasmic reticulum and swelling of mitochondria with tubular cristae. Plasma progesterone levels on the first two days of the cycle appeared to be correlated with luteal activity as corpora lutea were demonstrated to synthesize progesterone during this interval. Luteolysis occurred on day 3 with a reduction in luteal cell size accompanied by condensation of the agranular endoplasmic reticulum, regressive changes in the mitochondria, and a marked drop in luteal progesterone synthetic activity. On day 4, extensive phagocytic activity and luteal cell autolysis indicated an advanced involutional state. The short but functional luteal phase in the cyclic hamster does not appear to involve the production of 20α‐hydroxy‐pregn‐4‐en‐3‐one as occurs in the rat. This progestin was not detectable in plasma or luteal tissue before or after incubation at any time during the cycle. Possible mechanisms regulating luteal cell development and regression during the estrous cycle are discussed.