Brain selenium accumulation in rat pups of selenium supplemented mothers.

Selenium is essential for normal mammalian development. Being a component of antioxidant enzyme, glutathione peroxidase, it plays a major role in protecting the cells from free radical damage. The level of glutathione peroxidase was directly related to the amount of selenium present in various tissues and organs. A decrease in selenium leads to various pathological changes in humans as well as in various laboratory animals. The aim of the present study was to understand whether there is an increase in the level of selenium in different brain regions of rat pups whose mothers were supplemented with selenium, either 2 or 4 mg/l of their drinking water throughout the period of their pregnancy. There was a significant increase in the level of selenium in the cerebellum, cortex and hypothalamic and hippocampal tissues of selenium supplemented mothers as compared with those of non-supplemented mothers. The brain stem of these animals did not show any significant difference in the level of selenium. Furthermore, the differences in the level of selenium between the rat pups of 2 mg/l selenium supplemented mothers and 4 mg/l selenium supplemented mothers were not statistically significant. These studies suggest that supplementation of selenium to mothers during the period of their pregnancy can selectively increase the level of this trace element in different brain regions. Further studies are necessary to understand the significance of selective accumulation of selenium in specific brain regions on brain development and function.

Pre- and postnatal tissue selenium of the rat in the growing state.

The aim of this study is to quantify the selenium (Se) content (in microg/g) during different gestational periods in rat fetal tissues, and to follow up the changes in the Se content of the placenta, fetal head, liver and lung during gestation and postpartum periods. Locally reared virgin female Wistar rats were mated. Pregnant rats were sacrificed on days 15, 18 and 21 of pregnancy. Newborn pups at the age of 3 days and rats at the age of 1 month were also investigated. There was a gradual increase in placental and whole head Se content as gestation proceeded compared to day 15; however, the differences between the groups were not statistically significant. The liver Se content at day 18 of gestation was significantly higher than at day 21 of gestation and in rats at 3 days of age, but lower than the Se content of the liver of rats at the age of 1 month and the differences were statistically significant. The lung Se content was higher at day 18 of gestation than at day 21 and in the 3-day-old rats, and all differences between all groups were statistically significant except when the lung Se content at day 18 is compared to that of 1-month-old animals. The continuous increase in the Se content of the placental tissues and the whole head, although not significant statistically, may indicate that the fetus relies heavily on its supply of Se from the maternal blood and in part on the supply of thyroid hormones which are important for brain development, as evidence exists that T(4) and T(3) are present in the fetal brain in early fetal life before the onset of fetal thyroid function. The higher content of Se on day 18 and its decline on day 21 of gestation in the liver may imply that it is stored and being utilized partly in other tissues for other functions and particularly for thyroid hormone synthesis, metabolism and functions.

Changes in collagen content of the diaphragm in rats of different ages.

Rat diaphragm showed a nine to ten-fold increase in the dry and wet weights and a four-fold increase in its surface area between 21 and 540 days of age. The increase was the most rapid between days 21 and 90, thereafter a non-significant trend of increase was maintained at least up to 360 days of age followed by a tendency to decrease. The total collagen content of the diaphragm paralleled the increase in surface area with progressing age. The collagen content significantly dropped when expressed relative to the dry weight of the diaphragm, between 21 and 90 days of age. This trend was maintained till 180 days of age but thereafter significantly rise was seen. These later changes may be due to elenated synthesis and/or reduced degradation of collagen, and may contribute to the decline in contractility of the diaphragm as age advances.

Facial vessels of desert camel (Camelus dromedarius): role in brain cooling.

The reactivity of the superficial veins of the camel was investigated in vitro in response to stretch, heat, norepinephrine, and transmural nerve stimulation (TNS). Stretch at 30 degrees C or 37 degrees C produced a maintained tone and phasic contractions of the facial and nasal veins. The developed tone increased significantly with increasing the temperature (from 30 to 45 degrees C), especially in the proximal part of the buccal facial vein. Norepinephrine caused a constrictor response in the facial vein with the proximal part showing a lower maximum. TNS evoked a constrictor response in proximal segment and a dilator response in the more proximal segment of the buccal facial vein. Either responses were blocked by bretylium or tetrodotoxin. Morphological examination of the vasoactive segment of the facial vein showed a thick muscular layer and a valve in the proximal segment of the buccal facial vein. These results show functional variation in the distribution of adrenoceptors in the facial vein. The high-temperature sensitivity of the buccal facial vein suggests that this part could serve as a temperature-sensitive sphincter that diverts cool nasal blood to the brain for selective cooling of the camel brain during heat stress.

Presence of vesicular bodies and thick basal laminae in the nephron of the desert gerbil Meriones crassus.

Kidney samples of the adult gerbil Meriones crassus were aldehyde fixed and Epon embedded for studies of the general features of various parts of the nephrons, with particular attention to their basal laminae in all regions. Results obtained showed the presence of thick basal laminae (2-6 microns) in the parietal layer of Bowman's capsule, proximal convoluted tubule, thin loop of Henle and distal convoluted tubule. With the aid of the electron microscope, extracellular vesicular bodies were observed within the thick basal laminae in the previous regions. The bodies (50-500 nm in diameter) were found at various levels of the basal laminae. Some of them appeared to have been pinched off directly from the epithelial layer and to have moved to the underlying basal lamina, which may suggest that these vesicular bodies originated from the epithelial layer. The bodies, with a variable electron opacity, may be found either in small groups or as a single structure surrounded by a clear halo of basal lamina.

Changes in amniotic fluid cathepsins with gestational age.

Activities of the cysteine proteinases cathepsins B and H and of the chymotrypsin-like cathepsin G were determined in amniotic fluid of rats during the last third of gestation. Activities of cathepsins B and G were found to significantly increase with increasing gestational age while cathepsin H activity decreased. It was concluded that cathepsins may participate in the destabilization of fetal membranes and therefore may contribute to their rupture.

Heterogeneity of the histological features along the course of the facial vein of the desert camel (Camelus dromedarius): relevance to brain cooling.

Sections from different parts along the facial vein of the camel (Camelus dromedarius) were examined by light microscopy. The results demonstrated heterogeneity among the various segments. Particular attention was paid to a specific area in the buccal region which was previously shown by physiological experiments to have a temperature-dependent myogenic tone. The morphology of that area showed highly thickened media with prominent bands of circularly disposed smooth muscles infiltrating both the intima and the adventitia. The morphology described in this study correlates well with the function and gives further credence to the proposed role of the facial vein in cranial thermoregulation particularly under heat stress.

Premature rupture of fetal membranes changes in collagen type.

Collagen from the chorioamnion units from premature and term pregnancies was solubilized by limited pepsin digestion and subjected to SDS-PAG electrophoresis. Collagen types were quantitated by densitometry. It was found that collagen type III decreases and collagen type V tends to increase as gestational age advances. Investigating the relative abundance of collagen types at various membrane sites from term pregnancies revealed that type V decreases in the amnion as the rupture site is approached. It is concluded that since type V collagen is more resistant to collagenases, its decrease may predispose that particular site to rupture.

Site variability in the solubility of collagen of human fetal membranes.

The extractability of collagen was examined in different sites of amnion and chorion from term deliveries. Sequential extraction with NaCl, acetic acid and CaCl2 showed that soluble collagen accounted for 1.5% of the proteins extracted. Saline extracted more collagen from the amnion than from the chorion. Acetic acid and CaCl2 extracted decreasing and increasing amounts of collagen from the amnion and chorion respectively. The concentration of collagen decreased linearly in the chorion as the rupture site was approached. The results indicate differences in the nature of collagen between amnion and chorion as well as in various sites in the latter.

Ultrastructure of the intrahepatic bile duct system of the one-humped camel (Camelus dromedarius).

The ultrastructure of the intrahepatic bile duct system of the camel was studied. Bile canaliculi are present as cavities containing numerous microvilli between adjacent hepatic cells. They are lined with cuboidal cells surrounded by a basal lamina. The lateral plasma membranes of adjacent cells form extensive evaginations below tight junctions at the lumenal surface. The basal surface is open. Collagen bundles are arranged mainly in parallel to the duct.

Intact fetal membranes. Morphological predisposal to rupture.

Samples from different parts of the fetal membranes were examined by both light and transmission electron microscopy. Samples were obtained during elective cesarean section after full-term normal pregnancy. The results indicated that the different layers of the membranes had undergone ultrastructural changes varying according to the site from which the sample was taken. Samples taken from areas geometrically opposite to the placenta showed evidence of tension on the amniotic epithelium and disruption of the basement membrane. Samples taken from the area covering the internal os showed changes in the collagenous material. The implications of these findings are discussed.

Full-term and prematurely ruptured fetal membranes. An ultrastructural study.

The layers of the human amnion and chorion were examined by light and transmission electron microscopy. Comparisons among different anatomical sites with respect to full-term and prematurely ruptured membranes indicate that (a) the thickness of the membranes is reduced near the rupture point; (b) intercellular canals near the implantation site become dilated and branched; (c) the trophoblast layer of full-term membranes is thinner and with more degenerating cells; and (d) the fibroblast and spongy layers have fewer collagenous fibers and less organization near the rupture site. These findings suggest that, although cellular activity is maintained in prematurely ruptured membranes, the mainly collagenous extracellular matrix undergoes marked disorientation. If this occurs too early in gestation, it may lead to premature rupture.

Ultrastructural studies on the nucleoli of the follicle cells in the lizards Acanthodactylus scutellatus hardyi and Eremias brevirostris.

The ultrastructure of the nuclei in the ovarian follicular cells has been examined in the lizards Acanthodactylus scutellatus hardyi, and Eremias brevirostris. During certain growth stages, the nuclei of the intermediate and the pyriform cells become large and conspicuous, and usually contain numerous morphologically variable nucleoli. The latter may be nucleolonemal, compact, ring-shaped, "filamentous", "fine-filamentous", "amorphous" or "course-granular" in type, and the number and type in each nucleus seems to be related to the developmental stage. The type of nucleolus may indicate different phases of activity in the nucleus and may also suggest an association with the production of different types of RNA.

Tinea versicolor: ultrastructural studies on hypopigmented and hyperpigmented skin.

Punch biopsy specimens from 4 patients with confirmed diagnosis of tinea versicolor were investigated. Hypopigmented, hyperpigmented and uninvolved sites from the same subject were compared in relation to ultrastructural alterations as a result of infection with Malassezia furfur, by light, scanning, and transmission electron microscopy. Hyperpigmented skin had thicker stratum corneum than hypopigmented but both were thicker than the uninvolved skin. A large number of tonofilaments were noticed in hyperpigmented sites in stratum granulosum. In hypopigmented skin the melanosomes were individually dispersed and fewer in number than the uninvolved skin. In hyperpigmented skin, the melanosomes were sequestered in most cells suggesting difficulty in the transfer of melanosome granules to keratinocytes. In both cases of pigmentation the most readily affected parts of the cells were cytoplasmic organelles with a latent effect on the nucleus and nucleolus. We postulate that either stage of pigmentation (hyperpigmentation or hypopigmentation) is a intermediary in nature as a result of M. furfur invasion.

Study of the connective tissue of human fetal membranes.

No significant difference in collagen content per unit surface area was found for 3 different areas of the fetal membranes in relation to the rupture site. Electron microscopy examination revealed that tissue nearer the rupture site contained fewer collagen fibres than did the other 2 sites studied. It is suggested that collagen has been dissolved at the rupture site.

Bursting pressure and collagen content of fetal membranes and their relation to premature rupture of the membranes.

The collagen content and the bursting pressure of human fetal membranes was measured for full term spontaneously ruptured, full term artificially ruptured and prematurely ruptured membranes. The bursting pressure of the prematurely ruptured membranes was significantly higher than the membranes which ruptured spontaneously at term. No significant difference was found in the collagen contents.

The ultrastructures of binucleated follicle cells and migrated nuclei in the lizard Acanthodactylus scutellatus hardyi.

Binucleated cells and constricted nuclei have been observed in the polymorphic follicles during certain developing stages in both the intermediate and the pyriform cells. The formation of binucleated follicle cells may increase RNA synthesis and/or another function may be assumed which is the migration of these nuclei to the ooplasm. The migrated nuclei have been seen during certain stages in the ooplasm and are apparently taken into the ooplasms by phagocytosis, or through cytoplasmic bridges, but there is a great possibility that these nuclei enter the oocyte by the fusion of both cell membranes (the oocyte and the follicle cell cytoplasmic membrane). The number of these nuclei is not very large and often too small in each oocyte to permit a true nutritive function but it does enable DNA and RNA material to enter the ooplasm.

Angiolymphoid hyperplasia with eosinophilia. An electron microscopy study.

Ultrastructural investigation of a case of papular (dermal) lymphoid hyperplasia with eosinophilia revealed in the proliferating tissue rounded inclusion bodies made up of smaller particles which formed within the lysosomal vacuoles and sometimes occupied a large proportion of the cytoplasm. The bodies also occur in the extracellular spaces. Apart from this, groups of mosaic-like particles and concentric bodies with a central core suggesting viral provenance were demonstrated.

Effect of pregnancy on the collagen content of the oviduct in the lizard.

It was shown experimentally that both the growth and total collagen content of the oviduct in the lizard Acanthodactylus scutellatus hardyi are mainly dependent on the number of eggs present. There was rapid formation of collagen if more than two eggs were present.