Scanning electron microscopy最新文献

Little is known about in utero urinary bladder embryogenesis and the development of the urothelium of laboratory animals. Previous scanning and transmission electron microscopy studies in rats and mice have indicated that the highly specialized superficial cells of the urothelium complete their differentiation at a very late stage of fetal development or shortly after birth. Limitations in methodology in the past have precluded extensive examination of earlier stages of bladder development. Innovations in preparatory procedures of the bladder of rat fetuses have been developed which make possible detailed scanning and transmission electron microscopic and light microscopic examination of cloaca and urinary bladder as early as day 11 of gestation.

Published studies indicate that genes and dietary manganese deficiency cause vestibular defects and ataxic behaviors. Manganese deficiency during development causes otoconial defects in mice, rats, guinea pigs, and chicks. Mutant genes cause otoconial defects in mice, mink, and poultry. Manganese supplementation prevents the otoconial defects in some mutant mice and mink. Manganese is essential, before crystallization of the otoconia, for synthesis of mucopolysaccharides and otoconial matrix. Such defects can be induced, after otoconia are crystallized during fetal development, by dietary zinc deficiency and sulfonamide treatment (inhibits carbonic anhydrase, a zinc-requiring enzyme). Manganese and/or zinc supplementation ameliorates otoconial defects in pallid and lethal-milk (zinc-deficient) mice. Studies herein show that: Developing otoconia can be quantitatively labeled with 45 Ca. This may provide a means for studying calcium metabolism in otoconia over a prolonged period of time and for determining the possible effects of diet, drugs, and other factors on otoconia. Otoconial defects, induced after otoconia form in the fetus, were observed in newborn mice, but disappeared by two days after birth. Conditions of the inner ear may contribute to the calcification of otoconia. Manganese and zinc supplementation of pallid mice via acidified drinking water is more effective than dietary supplementation in preventing otoconial defects. The effectiveness of zinc but not of manganese is related to maternal genotype (+/pa vs. pa/pa). The effect of supplementation of the dams with zinc but not with manganese increases over successive litters. These studies indicate the potential for interaction of genes and trace minerals on otoconial formation and maintenance.

The crista ampullaris of the guinea pig and the bull frog were investigated by scanning electron microscopy. The crista ampullaris were freeze fractured or sheared followed by maceration with 0.1% OsO4 solution. Following this, three-dimensional intracellular structures were observed. The mitochondria of the sensory cells varied in shape from globular to long and slender. Golgi apparatus and endoplasmic reticulum of the sensory cells were also demonstrated clearly. Nerve elements, nerve endings and synaptic structures were also observed stereoscopically.

The basic function of the epidermis is to provide a barrier which will separate the body compartment from the environment thus protecting the organism from excessive loss of water and to hinder the entrance of noxious agents. A continuous renewal of the actual barrier makes it possible to fulfil these requirements. Using particle probe analysis, electron microprobe (EMP) and proton microprobe (PMP) analysis we have demonstrated the feasibility of these techniques in the study of skin physiology. The results reported here have been obtained on quench frozen skin specimens inertly prepared by cryotechniques to produce freeze-dried sections presenting cross sections of the skin. The distribution of Na and K is compatible with the idea that the Na/K pump of the cell membranes is dysfunctional above the basal cell layer. The phosphorus distribution over the epidermal cross section coincides with a previously shown phospholipid distribution. S and mass distributions correspond to the results of the keratin synthesis of the epidermis. Calcium displays a profile over the epidermis which is compatible with recent data obtained on the calcium dependence of the differentiation of epidermal cells in culture. Also this distribution corresponds to recent data obtained by histochemical methods at transmission electron microscope resolution. Zn and Fe have been shown to reside mainly in the basal cell layer of the normal epidermis but are found in high amounts in the outer cell layers of the epidermis in hyperproliferative paralesional psoriasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Four explanted porcine aortic valved conduits were examined using scanning and transmission electron microscopy. Sources of obstruction such as neointima or "peel" and calcification were observed. In one sample the neointima was found to possess an unusually large expanse of squamous cells partially lining the luminal surface. This lining much resembled a normal endothelium, which is not an expected feature of neointima. Cells, presumably of host origin, were noted upon the leaflet surfaces. They did not seem as well organized as those found on the neointima. Calcification did not seem greatly advanced but was clearly apparent. Certain treatments proposed by others to curtail calcification are discussed and amended herein. SEM examination of three of these conduits provided good evidence of lining cells on only the inflow surface of the leaflet. The fourth conduit, however, showed cells on both inflow and outflow surfaces. These cells possessed certain characteristics of cells from leaflets of the other three conduits, but questions remain as to the precise identification of all of these lining cells. TEM examination provided cytological evidence of macrophage-like cells lining the inflow surface of a leaflet.

In the present work, vessels casts in the inner ear of the rat and guinea pig, prepared by casting method using Mercox resin, were subjected to scanning electron microscopic examination and following results were obtained: In adult guinea pig, numerous capillary nets were found in the following parts: stria vascularis, spiral ligament, spiral prominence, Corti's organ, spiral ganglion, plexus cochlearis, semicircular ampulla, saccule, utricle, and endolymphatic sac. These were consistent with functionally and morophologically important areas in the inner ear. In the central side of the area with capillary nets, arterioles were found to run throughout, like a complex coil, and peripheral capillary diameter was found to be unchanged in an experiment in which the injection pressure was altered, thus autoregulation of blood flow into these important areas is assumed. Vessels in the planum semilunatum were found to form a specific loop-shaped route, where secretion and reabsorption of endolymph is thought to occur. After kanamycin injection into the tympanic cavity, stenosis was observed in capillary nets in the cochlear lateral wall. In guinea pigs on the 30th day of fetal life, the main stem of the inner ear vessel had already formed; however, the peripheral capillary nets were as yet immature in form and vessel density was low.

This report describes the effects of endotoxin treatment on the intrasplenic microcirculation and cellularity in rats. Four and 16 h after a single intravenous injection of endotoxin (2 mg/100g body weight), altered intrasplenic microcirculation was observed. The open circulation was reduced from 97% in the control rats to 79% in the endotoxin treated rats, while the closed circulation increased from 3% in the controls to 21% in the endotoxin treated rats. Such changes in the splenic microcirculation may be partly due to the presence of fibrin and the pooling of polymorphonuclear leukocytes and red blood cells in the red pulp. The most apparent cellular changes seen in the white pulp of endotoxin treated rats 16 h after endotoxin injection are the disappearance of lymphocytes from the periarterial lymphatic sheath and the appearance of many giant macrophages within the white pulp. The giant macrophages contain lymphocytes undergoing various stages of degradation. This suggests that the lymphocytes may be injured by endotoxin treatment and are subsequently phagocytosed by macrophages.

Platelet agonists and subendothelial extracellular matrix (ECM) induce morphological and biochemical changes in animal megakaryocytes, reminiscent of the response of platelets to the same substances. We have examined the behavior of human megakaryocytes exposed for up to 36 hours to the ECM produced by cultured bovine corneal endothelial cells. By phase contrast and scanning electron microscopy these megakaryocytes demonstrated non-reversible adherence and flattening with formation of long filopodia, thus confirming that human megakaryocytes acquire platelet functional capacities. In addition, megakaryocyte fragmentation into prospective platelets was apparently induced by the ECM. Up to 50% of the adherent megakaryocytes underwent spontaneous fragmentation into small particles which individually reacted like platelets on the ECM. The interaction of the megakaryocytes with the ECM was specific since no adherence, flattening or fragmentation occurred upon incubation of the megakaryocytes on regular tissue culture plastic or glutaraldehyde fixed ECM. Thus we have demonstrated platelet like behaviour of human megakaryocytes in response to this physiological basement membrane and a possible role of the subendothelium in platelet production which may occur in vivo as megakaryocytes cross the sinusoid walls and enter the blood stream.

The authors review the contribution of microcorrosion cast studies towards clarifying the structure of skeletal muscle microcirculation. Former studies performed on naturally contracted muscles show the presence of a primary and a secondary arterial network and a capillary network. At the level of the capillary network pericyte imprints are present. Muscles characterized by different types of metabolism show different features of the capillary pattern. Other authors have affirmed that the extended muscle is characterized by long and straight capillaries, while the contracted one features clusters of vessels all around a muscle fiber. The authors have made the present observations in order to determine how the capillary pattern of muscles with different metabolism is modified by extension and shortening of the muscle belly. The capillary pattern observed appears very similar to that observed in former studies. The differences between the oxidative and the glycolytic muscle are evident in every condition of the muscle belly. These data confirm the theory that there is a permanent endogenous difference in microcirculation between oxidative and glycolytic muscle, determined by muscle fiber metabolism.

We have used scanning electron microscopy (SEM) to examine the surface morphology of the renal epithelial cell lines MDCK and LLC-PKl to determine the influence of alternative culture substrate conditions on cell polarity. We observed that regardless of physical culture conditions, cells established and maintained polarity, expressed by the characteristics of apical and basal surfaces. Culture conditions did, however, influence the orientation of cell polarity in vitro. MDCK cells were grown within collagen gel, in which individual cells exhibited clonal growth to form fluid-filled epithelial cysts. The cells of MDCK-cysts were polarized with apical surface facing the lumen and basal surface against the surrounding collagen gel. This configuration made it possible to gain direct visual access, by SEM, to the basal surface by removing the supportive collagen lattice. The apical surface of MDCK-cysts was lined by short microvilli. Each cell possessed a solitary cilium. In comparison, the basal surface had few appendages, although cell boundaries were marked by interdigitating short processes. LLC-PKl cells in monolayer culture bore solitary cilia and long microvilli at their apical surface. The basal surface of cells involved in dome formation was observed to possess only a sparse population of short, blunt processes. When LLC-PKl cells were raised in stationary suspension culture or in monolayer atop non-culture grade plastic, they formed cysts with the cell apex facing the surrounding medium. These cells showed variable apical morphology. The cells of large, highly expanded cysts were often attenuated and had a relatively smooth apical surface. The basal surface of cells of fractured LLC-PKl cysts commonly was also smooth, without prominent appendages.