bluuebunny/crossref_metadata_2025 huggingface dataset:
Receptor‐mediated endocytosis of glucagon in isolated mouse hepatocytes
Authors: Watanabe Jun , Kanamura Shinsuke , Asada‐Kubota Mari , Kanai Kazuo , Oka Motoko
Published: February 2005

The binding of glucagon to the cell surface and the pathway of intracellular transport of the hormone in isolated mouse hepatocytes were studied by autoradiography, colloidal gold‐labeled glucagon (Au‐glucagon), and biochemical methods. In cells incubated with 1251‐glucagon at 4°C, the label was mainly localized to the plasma membrane even after 60 min of incubation. At 20°C, the labeled ligand was internalized by the cells and the amount of internalized ligand increased with time of incubation. At 37°C, the ligand was rapidly internalized and found to be associated with coated or uncoated vesicles. Au‐glucagon experiments revealed clearly the process of internalization of glucagon. Au‐glucagon bound to the plasma membrane was transported to coated regions and then internalized into vesicles via coated pits. Biochemical results supported these findings from autoradiography and Au‐glucagon experiments. Thus, glucagon is internalized by hepatocytes via receptor‐mediated endocytosis.
Effects of chronic ACTH stimulation on the morphology of the rat adrenal cortex
Authors: Pudney J. , Price G. M. , Whitehouse B. J. , Vinson G. P.
Published: February 2005

The effects of chronic ACTH treatment (Depot Synacthen, 100 μg/day) on the morphology of the rat adrenal were studied in animals treated for 1 to 18 days. The gross weight of the adrenal increased up to tenfold, but although mitotic figures were seen after 3 days in the glomerulosa region, most of this is attributable to a vast increase in blood content. After 3 days of treatment the sinusoids in the reticularis became extremely dilated, and red blood cells penetrated the endothelial wall to become tightly packed around the cortical cells. This led to the gross distortion of the organization of the cortical tissue and after 7 days the cells in the reticularis region were isolated from each other by the continual infiltration of red blood cells. These changes gradually progressed outward so that other regions of the cortex became similarly affected. Eventually the cord‐like arrangement of the fasciculata was disrupted. After 18 days of treatment, most of the cortex was involved and only a very thin layer of cells lying beneath the adrenal capsule was seemingly unaffected. Another major effect of corticotrophin treatment was the gradual loss of cellular differentiation, particularly of glomerulosa cells. Although the glomerulosa appeared normal after 1 day of treatment, cells of the fasciculata abut directly on the connective tissue capsule following 3 days of ACTH administration. Eventually glomerulosa cells disappeared almost completely, although there was no sign of cellular necrosis. It is likely that glomerulosa cells are transformed into fasciculata‐type cells under ACTH treatment. This interpretation is consistent with functional changes that occur at the same time, including the loss of aldosterone synthetic capacity.
In vivo experimentation on rat incisor enamel organs through a surgical window
Authors: McKee M. D. , Warshawsky H.
Published: February 2005

Experimental agents administered systemically are costly and often toxic to animals. An in vivo technique has been developed whereby a surgical window in the alveolar bone allows selected areas of the rat incisor enamel organ and underlying enamel to be exposed to various drugs, radiolabeled molecules, and molecular weight markers. Sherman rats weighing 100 gm were anesthetized and the inferior surface of each hemimandible was surgically exposed. A slow‐speed dental hand drill was used to drill a small hole through the alveolar bone overlying the secretion or maturation zones of the enamel organ. The wound was closed and during recovery the mechanical trauma to the underlying tissue moved away from the hole due to the continuous eruption of the tooth. Two to 5 days later the hole was reexposed and microinjections of 3H‐proline, 125I‐salmon calcitonin, vinblastine sulphate, and normal saline (as control) were administered through the hole with a micro‐manipulator and a microliter syringe. Radioautographic detection of 3H‐proline incorporation in secretory ameloblasts and enamel at 10 minutes, 30 minutes, 1 hour, 4 hours, 1 day, and 2 days after microinjection was identical to that obtained previously by systemic injection. Two hours after microinjection of vinblastine sulphate the cellular response was again identical to that following systemic injection; 125I‐salmon calcitonin (M.W. ∼ 3,600D) was used as a molecular weight marker and was seen to diffuse into the enamel of the maturation zone at 10 minutes after microinjection. This study has demonstrated the feasibility of this new technique for experimentation on rat incisor enamel organs.
The external genitalia of female pygmy chimpanzees
Authors: Dahl Jeremy F.
Published: February 2005

The external genitalia of four adult female pygmy chimpanzees (Pan paniscus) were examined during a 2‐year period. It was found that the labia majora are retained in adults of this species and that, when tumescent, the labia minora effectively relocate the frenulum and clitoris so that they point anteriorly between the thighs. When detumescent, the configuration of the labia minora and clitoris resembles that of immature common chimpanzees (P. troglodytes). It is suggested that the simple, structural relocation of the clitoris from the normal condition noted in adult P. troglodytes makes possible the homosexual, intergenital rubbing observed in P. paniscus, when ventroventral juxtaposition of the individuals permits eye‐to‐eye contact. In addition, this change probably increases sexual stimulation of the female during heterosexual, ventroventral copulations. The possibility of intense, face‐to‐face sexual interactions has been achieved by P. paniscus without the evolution of bipedalism and the consequent reorientation of the genitalia seen in Homo sapiens.
Effects of pinealectomy and melatonin administration on thyroid follicles of blind syrian hamsters
Authors: Vriend Jerry , Thliveris James A.
Published: February 2005

Since previous studies have shown that an active pineal gland exerts an inhibitory effect on circulating levels of thyroxin in the Syrian hamster, a study was conducted to determine whether the histology and ultrastructure of the thyroid gland supported the conclusions drawn from the hormone data. The ultrastructure of thyroid glands of blinded male Syrian hamsters was compared to that of intact controls kept under a 14L/10D photoperiod, to that of blinded hamsters also pinealectomized, and to that of blinded hamsters receiving 80 μg/ml of melatonin in the drinking water. Serum thyroxin (T4) and serum thyrotropin (TSH) concentrations were determined by radioimmunoassay. After 10 weeks serum thyroxin concentrations were less than 50% of controls and concentrations were significantly reduced. EM examination revealed that blinded hamsters had an increased number of follicular cells with flattened epithelium and nondilated endoplasmic reticulum compared to intact controls. In blinded hamsters that were pinealectomized or treated with melatonin in the drinking water, the ultrastructure of the thyroid was not different from controls and serum thyroxin concentrations were restored to near normal. These ultrastructural data support the conclusion that the pineal gland is required to obtain inhibition of the pituitary‐thyroid axis in blinded hamsters and that melatonin has a counter‐inhibitory effect when administered via the drinking water.
The allantois of the north american opossum (didelphis virginiana) with preliminary observations on the yolk sac endoderm and trophectoderm
Authors: Krause William J. , Harry Cutts J.
Published: February 2005

During the middle of prenatal day 10, the opossum allantois forms as a ventral outgrowth of the hindgut. By day 11 it appears as a large, fluid filled sac and by the middle of day 12 (just prior to birth) it reaches its maximal development. The simple squamous epithelium lining the allantois consists of only one cell type that often contains numerous filaments in the apical cytoplasm. At the luminal surface, the apices of the cells are united by junctional complexes and desmosomes are present between adjacent cells. The luminal surface is irregular, whereas laterally and basally the cell membranes show few if any infoldings. Mitotic figures and presumptive degenerating cells occasionally occur in the allantoic epithelium which rests on a delicate basal lamina. The allantois is covered by a simple squamous mesothelium that lacks a distinct basal lamina. Between the two epithelial sheets lie mesenchymal cells, collagen fibers, and blood vessels. No specializations of cell membranes were noted in either of the epithelial layers. The yolk sac endoderm consists of a single layer of squamous cells whose cytoplasm contains scattered profiles of rough endoplasmic reticulum and mitochondria. Extensive lateral and basal infoldings of the plasmalemma were not observed in these endodermal cells. The morphology of the trophectodermal (trophoblastic) cells indicates a cell type that is active in the transport of materials. Since the endodermal cells that line the allantois lack morphological features that would suggest the presence of mechanisms for transport or exchange, and because they remain relatively unchanged throughout pregnancy, it is thought that the allantois functions primarily in the storage of urinary wastes during prenatal life. As the allantois does not establish physical contact with the yolk sac placenta, it is believed that exchange between the developing fetus and mother occurs primarily through the activity of cells that form the trophoblast.
A comparison of histopathologic changes following x‐irradiation of mid‐thoracic and lumbosacral levels of neonatal rat spinal cord
Authors: Heard Jeanne K. , Ann Gilmore Shirley
Published: February 2005

Light microscopic changes were studied in the dorsal funiculi of spinal cords from rats irradiated (4000 R) at 3 days of age and killed from 9–60 days postirradiation (P‐I). The irradiated site was limited to a 5‐mm length of mid‐thoracic spinal cord (T only) in one group of rats, to a 5‐mm length of lumbosacral spinal cord (L only) in a second group, and to 5‐mm lengths of both mid‐thoracic and lumbosacral spinal cord (T/L) in the third group. Changes in the lumbosacral regions were essentially the same in both L only and T/L irradiated groups. These changes included a decreased neuroglial population and a concurrent state of hypomyelination from 9–30 days P‐I. In contrast, in the mid‐thoracic regions of T only and T/L irradiated groups the decrease in the neuroglial population was obvious only through 13 days P‐I, and by 30 days this population resembled that of the controls. The irradiated mid‐thoracic areas were hypomyelinated, with the fasciculus gracilis showing a greater degree of hypomyelination than the fasciculus cuneatus. By 25 days P‐I, myelination appeared to be normal in these areas. Scattered hemorrhages were noted in both lumbosacral and mid‐thoracic regions, but necrotic areas occurred only at the lumbosacral level. In general, the mid‐thoracic area appeared to be less sensitive to x‐radiation at 3 days of age than the lumbosacral area. These data suggest that there may be marked differences in the developmental states of cells at these two levels at 3 days of age.
Asymmetry of the human skull during fetal growth
Authors: Trenouth M. J.
Published: February 2005

Asymmetry of the human skull in the frontal and basal views has been described previously as a normal feature in adults. However, no investigation has been performed during the fetal period to see when asymmetry first develops. Previous quantitative methods for measuring asymmetry have relied upon defining anatomical points and using geometrical constructions. In the present study image outlines and their centroids (centers of area) were related to each other via a rectangular coordinate reference grid using the technique of morphanalysis. The centroids were shifted to the left relative to the coordinate reference grid indicating a left side expansion. Also the signed area under the cyclical curve, which is zero for a perfectly symmetrical shape, showed a negative shift indicating asymmetry. The cranium was found to be the major site of asymmetry caused by unequal development of the cerebral hemispheres. The asymmetrical development of the temporal lobes caused a greater displacement of the nasomaxillary segment on the left leading to a rotation of the face on the cranium.
Morphology of the distal conducting airways in rhesus monkey lungs
Authors: Tyler Nancy K. , Plopper Charles G.
Published: February 2005

This study systematically characterizes the organization and nature of epithelial populations in the distal airways of the adult rhesus monkey. Infusionfixed lungs were evaluated using airway dissection and scanning and transmission electron microscopy. We found that a true bronchiole free of cartilage and alveolar outpockets was not consistently present. Cartilage and alveolar outpocketings were often observed within the same airway generation. The epithelial population of nonalveolarized terminal conducting airways was pseudostratified columnar, consisting of ciliated, mucous, and basal cells. The respiratory bronchiole found immediately distal to the terminal conducting airways had two clearly demarcated zones of distinctly different epithelial populations. Overlying the pulmonary artery was the same pseudostratified ciliated columnar epithelial population observed in nonalveolarized terminal airways. The epithelial population in the remainder of the respiratory bronchiole, not associated with the pulmonary artery, was simple nonciliated cuboidal with a few squamous cells. The cuboidal nonciliated bronchiolar cell differs from the mucous cell by having few small granules and rough and smooth endoplasmic reticulum. The extension of the ciliated, mucous, and basal cells several generations into the respiratory bronchiole in rhesus monkey has not been observed in rodents and other laboratory mammals. Data from studies of human airways, although not explicit, suggest that the rhesus monkey epithelial cell pattern resembles the pattern in the human terminal airways.
Decidua‐associated changes in guinea pig uterine blood flow and volume: Relation to uterine norepinephrine concentrations
Authors: Garris David R. , Dar M. S.
Published: February 2005

Changes in uterine blood flow (UBF) and uterine blood volume (UBV) during decidual tissue (DT) formation in the guinea pig were assessed at 2, 6, and 10 days postuterine trauma (PT). Uterine weight increased steadily between days 2 and 10 PT in DT‐bearing animals as compared with the constant uterine weights observed in controls. Both UBF and UBV levels were elevated between days 2 and 10 PT in DT‐bearing animals as compared with controls with the vascular changes being histologically related to the progressive stromal differentiation. Uterine norepnephrine (NE) levels were significatly (P ≤ 0.05–0.01) depressed in the hyperemic, DT‐bearing uteri as compared with controls. These results indicate that the uterine hyperemia associated with DT formation in the guinea pig involves a sustained increase in uterine vascular volume as well as vascular perfusion rate under conditions of depressed uterine NE levels. These events are intimately associated with the support of stromal differentiation in the guinea pig.
Morphometry of postnatal development in the porcine lung
Authors: Winkler Gian C. , Cheville Norman F.
Published: February 2005

Alveolar regions of normal pig lungs (newborn to 60‐day‐old) were characterized morphometrically to provide a basis for comparison in future investigations of porcine respiratory diseases. Endotracheal installation of fixative was done to expand the lungs uniformly at total capacity. Differential effects of lobar variations were determined by stratified random sampling of lung lobes. A stereologic study was done by point and intersection counts on electron micrographs. At birth, the lungs were remarkably well developed. Relative alveolar and capillary surface densities and air‐blood tissue barrier thicknesses were at adult levels. In allometric regressions, volumes and surfaces of lung components regressed directly to lung volume, but monoexponentially (to the 3/4 power) with body weight. In the first postnatal week, however, relative volume densities of cellular interstitium in septal tissue and of capillary lumina in parenchyma increased at statistically significant levels. Composition of lung parenchyma and septa was changed, although without statistically significant direct impact on parameters related to gas exchange. Type II pneumocytes had increased nuclear to cytoplasmic volume ratios in 7‐ to 14‐day‐old pigs, probably reflecting cell activation and increased surfactant production. Age (postnatal lung growth) created the most substantial variance of results; interanimal variation in pigs of the same age was less important and no consistent lobar variations were seen.
Ruthenium red staining of vaginal epithelial cells and adherent bacteria
Authors: King Barry F.
Published: February 2005

The vaginal epithelium of the rhesus monkey is a keratinized stratified squamous epithelium throughout the menstrual cycle and early pregnancy. The superficial cells have a thickened cell envelope, surface microridges, and numerous adherent bacteria. During later pregnancy the cells mucify and have a typical cell membrane, microvilli, and no adherent bacteria. In the present study we have extended these observations by examining vaginal surface structures after ruthenium red staining. Throughout the cycle, the superficial cells have a thin layer of stained material closely associated with the cell membrane, but in some cases a much thicker mucous blanket was observed. During later pregnancy the epithelial cells had a moderately thick, somewhat clumped ruthenium red‐positive material associated with the cell membrane. Glycocalyx components of the surface of many bacteria also stained with ruthenium red. The adherence of many types of bacteria to the vaginal epithelial cells appears to be effected by the interaction of polyanionic components on the surface of both the bacterial and epithelial cells.
Distribution and characterization of anionic sites in the basal lamina of developing human amniotic epithelium
Authors: King Barry F.
Published: February 2005

We have studied the distribution of anionic sites in the basal lamina of developing human amniotic epithelium by using the cationic stain ruthenium red. Amnions at 7–12 weeks of gestation and at term contained ruthenium redpositive granules in a quasi‐regular array on both the cellular and interstitial sides of the lamina densa. In order to characterize the anionic sites, small pieces of amnion were incubated in the presence or absence of either chondroitinase ABC, neuraminidase, Streptomyces hyaluronidase, or heparitinase in appropriate buffer systems. Incubation in the presence of heparitinase resulted in the complete disappearance of the basal lamina‐associated granules, but other enzymes tested had no demonstrable effect on these granules. We conclude that the anionic sites associated with amnion basal lamina, and demonstrable with ruthenium red, consist of glycosaminoglycans rich in heparan sulfate, probably present as heparan sulfate proteoglycan. Because amniotic fluid has a low protein content and amniotic epithelium (at least at term) lacks tight junctions, we postulate that the heparan sulfate proteoglycan associated with the amnion basal lamina may have an important function as a permeability barrier to anionic macromolecules.
Functional differences between sinusoidal endothelial cells and interlobular or central vein endothelium in rat liver
Authors: Yokota S.
Published: February 2005

The fine topological relationship between sinus‐lining endothelial cells (SLE) and vessel‐lining endothelial cells (VLE) at the opening portion of sinusoids into central or interlobular veins of rat liver was studied by a comparison of morphological and functional properties of both types of cells. Three minutes after intravenous injection of formalin‐denatured albumin conjugated with horseradish peroxidase (HRP‐FDA), liver was perfused with fixative. Chopped sections of the liver (50 μm thick) were incubated in diaminobenzidine‐H2O2 medium, followed by processing for electron microscopy. The HRP‐FDA was localized in endocytotic vesicles and vacuoles of the SLE and Kupffer cells but not of the VLE lining interlobular or central veins or interlobular arteries. In the opening portion of the sinusoids into these veins, the attenuated cytoplasmic extensions of the SLE containing positive vesicles were in direct contact with squamous process of the VLE having no positive vesicles. The contact was mediated by overlapping junctions. No intermediate cell type between the SLE and VLE in this region or other portions was noted. The results indicate that the habitat of the SLE is exactly isolated from that of the VLE in rat liver and at the transitional portion from sinusoids to veins or arteries they are directly connected with each other by overlapping junctions.
An immunofluorescent analysis of lectin binding to normal and regenerating skeletal muscle of rat
Authors: Gulati Adarsh K. , Zalewski Andrew A.
Published: February 2005

Ten different fluorescein‐conjugated lectins of various known sugar specificities were used to study cell surface glycoconjugates of normal and regenerating rat skeletal muscle. In normal muscle, Canavalia ensiformis agglutinin, Triticum vulgaris agglutinin (wheat germ agglutinin, WGA), Ricinus communis agglutinin‐I, and Maclura pomifera agglutinin bound strongly to the endomysial region of the myofibers. No binding was observed in the cytoplasm of the myofibers. Other lectins (Dolichos biflorus agglutinin, Griffonia simplifolia agglutinin I and II, Ulex europaeus agglutinin, Arachis hypogaea agglutinin, Glycine max agglutinin) bound very poorly or not at all in the normal muscle. Skeletal muscle degeneration and regeneration was induced by autotransplantation of the extensor digitorum longus muscle. In the transplanted muscles, the endomysial lectin binding of the degenerating myofibers became weak and lacked continuity, indicating a breakdown of the endomysium. Of all the lectins tested, only WGA revealed intense binding in the myogenic zone of regenerating muscle. As the regeneration progressed, this WGA binding became restricted to the new endomysium. In completely regenerated muscle, binding of all lectins was similar to that seen in normal muscle. The specific binding of WGA to the myogenic zone may be important in identifying factors or glycoconjugates, which constitute a favorable environmnt for skeletal muscle regeneration.
The renin‐angiotensin system in the rat anterior pituitary: Colocalization of renin and angiotensin II in gonadotrophs
Authors: McKenzie James C. , Naruse Kiyoko , Inagami Tadashi
Published: February 2005

Discovery of components of the renin‐angiotensin system (RAS) in the adenohypophysis of several species has prompted speculation concerning the location and possible function of a pituitary RAS. Although both renin and angiotensin II have been localized within the rat adenohypophysis, their colocalization has not been previously demonstrated within the same cells. In the present study, immunohistochemical staining by the avidin‐biotin‐peroxidase complex technique was used to demonstrate the coexistence of renin and angiotensin II in adenohypophyseal cells identified morphologically and immunocytochemically as gonadotrophs. These results support the existence of an adenohypophyseal RAS, at least part of which is under intracellular control. The influence of this system on control of fluid balance, blood pressure, and the secretion of other hypophyseal hormones is discussed.
Supplemental clinical dissections for freshman gross anatomy
Authors: Cahill Donald R. , Cramichael Stephen W.
Published: February 2005

This paper describes a series of nine short clinically oriented dissection exercises as supplements for freshman gross anatomy courses. These procedures heighten and focus student interest, and they do not extensively lengthen the time required to accomplish the regular dissection assignments. The exercises are: (1) lumbar puncture, (2) anterior approach for shoulder arthroplasty, (3) acromioclavicu‐lar dislocation, (4) fenestration of the diaphragm, (5) appendectomy, (6) cholecystectomy, (7) display of the facial nerve as in parotidectomy, (8) posterior approach for hip arthroplasty, and (9) injuries to the knee ligaments and meniscectomy.
Filipin‐sterol complexes in the plasma membrane of zebrafish spermatozoa
Authors: Kessel R. G. , Tung H. N. , Roberts R.
Published: February 2005

The presence and distribution of filipin‐sterol complexes in the plasma membrane of zebrafish (Brachydanio rerio) sperm was investigated. The zebrafish sperm plasma membrane, treated with freeze‐fracture techniques, is seen to contain a multitude of intramembranous particles that, in a specific region of the posterior part of the sperm head, are organized into unusual particle arrays that appear as simple hexagons or parallelograms. The polyene antibiotic filipin forms complexes with 3‐β‐OH sterols to produce characteristic protrusions and pits in membranes that are readily observable in freeze‐fracture replicas. Numerous filipin‐sterol complexes were found to populate the sperm plasma membrane, and the complexes exhibited variability in their distribution in different sperm. This appears to be the first illustrated example of an acrosomeless sperm that exhibits a high concentration of filipin‐sterol complexes. In contrast, the unique grating formed by the intramembranous particles as well as variable amounts of membrane surrounding the unusual particle arrays were always free of the filipin‐sterol complexes. Thus, while cholesterol appears to be present in the plasma membrane of the zebrafish sperm, it is not apparent in the highly differentiated region of the membrane based on the observed distribution of the filipin‐sterol complexes.
Immunohistochemical observation on substance P in regenerating taste buds of the rat
Authors: Nishimoto Tatsuya , Ichikawa Hiroyuki , Wakisaka Satoshi , Matsuo Saburo , Yamamoto Katsuhiko , Nakata Terukuzu , Akai Michio
Published: February 2005

The present study was performed to investigate the relationship between substance P‐positive (SP‐positive) nerve fibers and regeneration of taste buds in the foliate papillae of the rat by means of immunohistochemistry. It was confirmed by neurotomy that taste buds in the foliate papillae of the rat were innervated mostly (90%) by the glossopharyngeal (IXth) nerve and partly (10%) by the chorda tympani. In this experiment, the IXth nerve was sectioned distal to the petrosal ganglion. The rats were sacrificed at various intervals from 20 days to 80 days after the operation. In the course of denegeration and disappearance of taste buds, both SP‐positive fibers and taste buds disappeared completely from the posterior folds of the foliate papillae 7 days after the operation. Within 22 days, regenerated SP‐positive fibers began to appear in the lamina propria, and following the penetration of the fibers into the epithelium, taste bud anlagen reappeared at the bottom of the trench, and in the posterior folds at 24 days. The process of new taste bud formation extended toward the apex of the trench and to the anterior folds, which seemed to follow the regeneration in the nerve trunk. Quantitative data showed a gradual increase in the number of taste buds and taste buds containing SP‐positive fibers. These findings indicate that SP might have a role in regeneration of taste buds.
Rapid formation of gap‐junction‐like structures induced by glycerol
Authors: Kachar Bechara , Reese Thomas S.
Published: February 2005

Intercellular junctions, in identified in freeze‐fracture by narrowing of the intercellular gap and codistribution of P‐face membrane particles, proliferate during incubation of excised rat prostate tissue in 30% glycerol solution. These junctions fulfill the criteria used to identify gap junctions in freeze‐fracture replicas with respect to the size and uniformity of their component particles, the codistribution of the particle aggregates on P‐faces of adjacent membranes, and the narrowing of the extracellular cleft at the junction. These gap‐junction‐like structures form on the lateral surfaces of epithelial cells, where they are normally scarce, within minutes after exposure to glycerol. Glycerol‐induced junction formation is not blocked by DNP, a metabolic uncoupler, or by cycloheximide, a protein synthesis inhibitor. Newly formed junctions occur initially in clusters and the number per cluster decreases as individual junctions become larger with longer periods of incubation, suggesting that the clusters coalesce. The structural changes that precede and accompany the formation of these junctions at early times of incubation are comparable to the changes reported to precede the formation of gap junctions accompanying hormonal treatment, development, and other means of natural induction.
Immunofluorescent localization of an androgen‐dependent isoenzyme of prostatic acid phosphatase in rat ventral prostate
Authors: Terracio Louis , Rule Allyn , Salvato John , Douglas William H. J.
Published: February 2005

Isoenzymes of rat ventral prostate (RVP) acid phosphatase were isolated and partially purified by ultracentrifugation, Sephadex G‐100 column chromatography, and isoelectric focusing. Antisera were raised to the isoenzymes of prostatic acid phosphatase by immunization of New Zealand white rabbits. Rabbit antisera reacting specifically to homologous but not heterologous isoenzymes of acid phosphatase were then reacted with a variety of tissues using indirect immunofluorescence. The tissues included prostate, spleen, bone marrow, liver, kidney, salivary gland complex, small intestine, and adrenal glands. An antiserum against a RVP acid phosphatase isoenzyme with a pI of 4.5 (A‐PAP) localized acid phosphatase only in the supranuclear region of rat ventral prostate epithelial cells, and did not react with acid phosphatase in any of the other organs tested. A‐PAP did not localize acid phosphatase in the ventral prostate from rats 14 days after castration. A‐PAP did localize acid phsophatase in the ventral prostate from castrated animals that were treated with testosterone. These results indicate the A‐PAP localized an androgendependent isoenzyme of acid phosphatase in RVP epithelial cells that may be secretory in nature. This antiserum should prove to be an ideal marker for studies involving hormonal regulation of prostatic epithelial function in vivo and in vitro.
A functional and structural heterogeneity is formed among fetal rat hepatocytes during culture
Authors: Asada‐Kubota Mari
Published: February 2005

Fetal rat hepatocytes (22‐day‐old, full‐term) in vivo were homogeneous in ultrastructure and glucose 6‐phosphatase (G6Pase) distribution throughout the liver acinus. These cells were isolated and cultured for 17 days in Williams medium E containing 10% fetal calf serum, dexamethasone, insulin, and glucagon. Heterogeneity among hepatocytes appeared progressively during culture. There were variations in numbers of binucleated cells, cytoplasmic ultrastructure (e.g., in the distribution of glycogen and the quantity of ultrastructure (e.g., in the distribution of glycogen and the quantity of mitochondria), and intensity of histochemical reactivity for G6Pase. The cells could be classified generally into two types: type I cells had some characteristics of periportal hepatocytes and type II cells those of centrolobular hepatocytes in in vivo adult liver. The results show that a functional and structural heterogeneity can be formed among fetal hepatocytes in monolayer culture without differences in supply of oxygen, nutrients, and hormones. A hidden heterogeneity might already exist among hepatocytes in full‐term fetuses even though it cannot be detected ultrastructurally or cytochemically.
Partial denervation of the ovaries by transection of the suspensory ligament does not inhibit ovulation in rats treated with pregnant mare serum gonadotropin
Authors: Selstam Gunnar , Norjavaara Ensio , Tegenfelt Tomas , Lundberg Sven , Sandström Christina , Persson Sven‐ÅKe
Published: February 2005

Adrenergic nerves reach the ovary via two routes: along the arteries to the ovary and via the suspensory ligament. Results from earlier investigations suggest that denervation of the nerves along the arteries does not influence the ovulatory process. In the present study we have examined whether denervation by transection of the ovarian suspensory ligament influences the ovulatory process.

Partial denervation of the ovary by transection of the ovarian suspensory ligament, sham operation, or only anesthesia were performed on immature 25‐day‐old rats. To induce ovulation, pregnant mare serum gonadotropin (PMSG) was injected in the morning (0800‐0930), when the rats were 26 days old. This PMSG treatment normally induces ovulation around 0200 in the early morning of day 29 with subsequent formation of corpora lutea. Rats were killed 5–8 hr, 3 days, and 5 days after this ovulation time.

Ovarian interstitial norepinephrine levels were markedly decreased after transection of the suspensory ligament. Ovulations had occurred in all denervated, as well as sham‐operated, and control rats. The various groups did not differ in the number of ovulations per rat. Thus, the adrenergic nerves in the suspensory ligament appear not to be necessary for ovulation. Whether catecholamines themselves play a role in the ovulatory process cannot be elucidated from this experiment, since the norepinephrine content in the ovary was not totally depleted. It seems unlikely that adrenergic nerves reach the corpus luteum via the suspensory ligament, since transection of this structure did not change the luteal content of norepinphrine.
Small‐granule APUD cells in relation to airway branching and growth: A quantitative, cartographic study in syrian golden hamsters
Authors: Sarikas Stephen N. , Hoyt Richard F. , Sorokin Sergei P.
Published: February 2005

Small‐granule APUD cell clusters and their clear‐cell precursors were mapped in serial 2‐μm glycol methacrylate‐embedded, periodic acid‐Schiff(PAS)‐lead hematoxylin‐stained sections of 13‐, 14‐, and 15‐day fetal hamster lungs. Every sixth section was drawn from a camera lucida projection on tracing paper. Each tracing included the profiles of nonalveolated air passages and the locations of smallgranule cell clusters and solitary clear cells. Airways containing ciliated cells and those surrounded by condensed mesoderm were also labeled. Single clear cells were rare in fetal hamster lung. Of 2,368 endocrine cell loci identified in the three fetal age groups examined, only 14 were single clear cells. A preliminary survey of the entire left and right lungs showed that the pattern of airway and small‐granule cell development in the infracardiac lobe was similar to that occurring in the remainder of the lung; this lobe was accordingly considered a model for the whole lung, and the ontogeny of its small‐granule cell population was quantitated and compared with results of similar quantitative mapping of this lobe in an adult animal (Hoyt et al., 1982a,b). Along the lobar bronchus of the 13‐day infracardiac lobe and proximal portions of its main branches, small‐granule cell clusters occurred most often near airway intersections. As the number and density increased in subsequent fetal stages, small‐granule cell clusters became conspicuous along internodal bronchial segments. In distributing bronchioles, the population density of small‐granule cell clusters decreased between 13 and 14 days but more than doubled by day 15. Unlike human lungs, where centrifugally developing small‐granule cell clusters are firmly established in terminal bronchioles well before birth, most peripheral bronchioles in fetal hamster were devoid of small‐granule cell clusters, even at 15 days, one day before birth. Comparison of numerical population densities in this lobe of fetal and adult lungs indicates that small‐granule cell clusters continue to form past day 15 and suggests that they are considerably more numerous in adult than fetal lung.
Development of hamster tracheal epithelium: II. Cell proliferation in the fetus
Authors: McDowell Elizabeth M. , Newkirk Carnell , Coleman Bill
Published: February 2005

Proliferation of epithelial cells in the fetal trachea was studied in hamsters, beginning on the 10th gestational day and ending on the 16th day, shortly after birth. The mean mitotic index (MI) was highest on day 10, with no statistical confirmation of a change between days 10 and 11. The MI fell to about 2% on days 12 and 13, and declined thereafter to about 0.3% on day 16. The MIs for dorsal and ventral surfaces were compared and values were similar except on day 10, when ventral exceeded dorsal, and on day 12, when dorsal exceeded ventral, 2.56% and 1.3%, respectively. On days 10, 11, and 12 the epithelium was simple, composed of poorly differentiated columnar cells that proliferated. On day 13 the epithelium was pseudostratified owing to the presence of a few short cells that did not reach to the lumen. Throughout the fetal period, proliferation of columnar cells predominated but division of short (basal) cells increased from 8% to 40% of the total mitotic activity between day 13 and day 15. Proliferation of basal cells then declined, so that on day 16, 84% of all cells in mitosis were columnar. If basal cells divide to make more of themselves they must proliferate rapidly between day 13 and day 15, because they were virtually absent on day 12 but accounted for about 36% of the ventral and 23% of the dorsal epithelial cells on day 16. Based on the results, a hypothetical model is proposed for the formation of pseudostratified mucociliary epithelium. The model proposes that small granule (endocrine) cells, basal cells, secretory cells, and ciliated cells are established from poorly differentiated columnar cells by day 13. Thereafter short basal cells replicate to produce only basal cells, whereas columnar secretory cells replicate to produce secretory cells and ciliated cells. This model will be tested in future studies.
Teratogenic effects of the organophosphate insecticide dicrotophos (Bidrin): Histological characterization of defects
Authors: Garrison James C. , Wyttenbach Charles R.
Published: February 2005

White Leghorn chicken eggs, specific pathogen free, were treated with the organophosphate insecticide dicrotophos and the early defects thus induced were characterized histologically. Eggs were incubated for 24, 48, 72, or 96 hr, injected with doses of dicrotophos ranging from 250 μg to 2.0 mg per egg, and observed after an additional 48 hr of incubation. Treated embryos displayed general developmental retardation as well as unilateral retardation of the cranial sense organs, the youngest embryos being most severely affected. Many embryos injected with insecticide at 24 hr, and all but one injected at 48 or 72 hr, displayed notochordal folding, usually restricted to the cervical region; most of these also showed deformities of the adjacent spinal cord. Other defects, seen on a less consistent basis, included branching of the neural canal in the lumbar region, bifurcation of the neural epiphysis, deformation of the lens vesicle, and distention of the major blood vessels. The incidence and severity of epiphyseal, lens, and vascular defects were greatest among embryos treated at 24 hr, whereas notochordal and both types of neural defects were greatest among those treated at 48 hr. The incidence and severity of the abnormalities diminished with increasing age such that by 96 hr the only defect noted was a weak notochordal folding in one embryo. To a lesser extent, incidence and severity were dose‐related also. Histological similarities between embryos displaying vascular distention and recently dead treated embryos suggested that this abnormality is a precursor to death. All defects were associated with the presence of the insecticide at the time the affected structures were undergoing initial or early morphogenesis or else the deposition of a supportive sheath, suggesting these activities as targets of the teratogen.
Cytochemical and biochemical glucose 6‐phosphatase activity in skeletal muscle cells of mice
Authors: Watanabe Jun , Kanamura Shinsuke , Kanal Kazuo , Shugyo Yoshihiko
Published: February 2005

Cytochemical and biochemical glucose 6‐phosphatase (G6Pase) activity and fiber type composition were studied in soleus (SOL) and gastrocnemius (GC) muscles of mice. The SOL is a red muscle which contains numerous type I fibers (60%) and relatively few type II fibers (40%). The GC is a white muscle which contains numerous type II fibers (90–100%) and very few type I fibers (0–10%). In the SOL and GC, cytochemical G6Pase activity was localized in the sarcoplasmic reticulum, lateral elements of triads, myonuclear envelope, and in the endoplasmic reticulum and nuclear envelope of endothelial cells. Differential centrifugation showed that G6Pase activity was recovered in the 105,000g pellet (microsomal fraction). Histochemical enzyme activity in type II fibers was slightly higher than that in type I fibers. Biochemical G6Pase activity in the GC was significantly higher than that in the SOL. The possible functional significance of G6Pase in skeletal muscles was discussed.
Intraventricular blood vessels of the hypothalamus of Salmo gairdneri and Gambusia affinis
Authors: García José M. , Alvarez‐Uría Manuel
Published: February 2005

The ultrastructure of the hypothalamic intraventricular blood vessels is studied in two fish: Salmo gairdneri, a primitive teleost and Gambusia affinis, a modern teleost. Morphological differences found between vessels belonging to the lateral and medial recesses in Salmo are described as well as contrasted with those of Gambusia.

The endothelial cells are joined by elaborate tight junctions in both teleosts and also by desmosomes in Gambusia.

These vessels are continuous capillaries with pericytes which lack junctional complexes. The perivascular cells of the larger vessels display morphological characteristics of myoid cells.
Cytoplasmic surface ultrastructures of cardiac gap junctions as revealed by quick‐freeze, deep‐etch replicas
Authors: Shibata Yosaburo , Yamamoto Torao
Published: February 2005

Rapid‐freeze, deep‐etch, rotary‐shadow replica studies were performed to examine the cytoplasmic surface membrane of the cardiac gap junctions of rats, mice, and guinea pigs. In quick‐frozen fresh cardiac muscles, while the nonjunctional cytoplasmic surfaces were covered with filamentous materials, the cytoplasmic surface membrane continuous with freeze‐fractured gap junction plaques were relatively free of such filaments and revealed particulate patterns. After brief rinsing in high K buffer, gap junction membranes showed granular substructures resembling a tiled surface made of round tiles of various sizes. After prolonged rinsing for more than 20 min, however, cytoplasmic surfaces of gap junctions became less particulate but rather smooth. The particulate substructures observed in the rapid‐freeze deep‐etch replicas may correspond to the fuzzy cytoplasmic layer in thin sections and serine protease sensitive peptide moiety in sodium dodecyl sulfate‐polyacrylamide gel electrophoresis reported in isolated cardiac gap junction pellets. These cytoplasmic components, which are absent in liver gap junctions, seem to be specific in cardiac and neural gap junctions and may be related to the large electrical current passed by these junctions.
Ultrastructure and cytochemistry of thyroid lysosomes following subtotal thyroidectomy
Authors: Krupp Patricia P. , Lee Kathleen P.
Published: February 2005

Following subtotal thyroidectomy, the amount of circulating thyroid hormone decreases and causes an increase in the secretion of thyrotropin (TSH) by the anterior pituitary gland. Serum levels of circulating TSH remain elevated until thyroid secretion returns to normal. In this study we have analyzed the effects of such chronic stimulation of thyroid cells by TSH, with particular emphasis on ultrastructural and cytochemical changes in the lysosomes. Weanling Sprague‐Dawley rats underwent subtotal thyroidectomy and 6 weeks later the residual thyroid tissue was removed and processed for ultrastructural and cytochemical analysis. There were obvious ultrastructural signs of hyperactivity. The cells were hypertrophied and there were colloid droplets in the cells as well as extremely abundant oddly shaped lysosomes. The lysosomes reacted positively for acid phosphatase and for glycoproteins, suggesting that they are secondary lysosomes, ones which have complexed with thyroglobulin prior to release of thyroid hormones from the cells. This tremendous increase in the number of these structures in the cells is similar to that observed under normal conditions during the aging process and suggests a slowdown in the proteolytic degradation of thyroglobulin during long periods of chronic stimulation by TSH.
Inhibition of membrane bone formation by vitamin A in the embryonic chick mandible
Authors: Tyler Mary S. , Dewitt‐Stott Rachel A.
Published: February 2005

Embryonic chick mandibles (Hamburger and Hamilton [HH] stages 17–25) were cultured in the presence of various concentrations of vitamin A to determine the effect of hypervitaminosis A on membrane bone formation. In normal development, the mandible differentiates a centrally located Meckel's cartilage surrounded by membrane bones. Mandibles cultured without added vitamin A differentiated normally, though the timing of differentiation was retarded from that in ovo. Treatment with vitamin A interfered with skeletogenesis to varying degrees depending upon the initial age of the explant and the concentration of vitamin A. At low concentrations of vitamin A (1 μg/ml), neither cartilage nor membrane bone formed in young explants (HH stage 17), whereas cartilage formed in 78% and membrane bone in 11% of older explants (HH stage 25). Higher concentrations of vitamin A (2–4 μg/ml) inhibited membrane bone formation in all explants, and 4 μg/ml of vitamin A inhibited chondrogenesis in most (88%) of the older explants. To determine whether tissue interactions influence this effect of vitamin A on skeletogenesis, mandibular mesenchyme was separated from its epithelium and treated with vitamin A. Under normal culture conditions, isolated mesenchyme (HH stage 25) differentiated both cartilage and membrane bone. Hypervitaminosis A inhibited membrane bone formation in the isolated mesenchyme at all levels tested (1–4 μg/ml) and inhibited chondrogenesis at levels 2–4 μg/ml. Hence, vitamin A can act directly upon the mesenchyme to inhibit both membrane bone formation and chondrogenesis, but its action is mitigated by the presence of the epithelium.