Oxytocin in Leydig cells: an immunocytochemical study of Percoll-purified cells from rat testes.

Testicular interstitial cells, from rats aged 35 days, were dispersed with collagenase and separated through Percoll into 5 fractions (I-V); fraction I being the least dense. Measurement of basal testosterone production, histo-enzymological staining for 3 beta-hydroxysteroid dehydrogenase activity and electron microscopy indicated that the majority of Leydig cells were found in fraction IV (corresponding to a density of 1.076-1.097 g/ml). In addition, cells from this fraction responded to hCG treatment in a dose-dependent manner on day 0 and remained responsive after being cultured for 1 day. Immunostaining for oxytocin indicated that this fraction also contained the majority of the oxytocin-immunoreactive cells. On day 1 of culture, 56% of the cell population from fraction IV were positively stained for the steroidogenic enzyme and 75% immunoreactive for oxytocin. This overlap indicates that the Leydig cells were also the oxytocin immunoreactive cells.

The flow of blood cell suspensions through 3 microns and 5 microns Nuclepore membranes: a comparison of kinetic analysis with scanning electron microscopic examinations.

This study was designed to investigate the effect of red and white cells on the flow of dilute suspensions of blood cells through 3 microns and 5 microns Nuclepore membrane filters. The rate of flow of blood cell suspensions through 3 microns or 5 microns membranes declines continually due to occlusion of pores by slow cells. The cells which occlude 3 microns pores exceed the number of white cells about seven-fold. Electron microscopic examination of a used membrane confirms that these slow cells are not white cells but are red cells which are visibly damaged. With 5 microns membranes, the number of slow cells is entirely consistent with them being white cells. Again, electron microscopic examination confirms that 5 microns pores are occluded by white cells. With both types of membrane, the same kinetic analysis is valid and yields information about the behaviour of red cells during the filtration procedure.

Evaluation of the contribution of red and white cells to the flow of suspensions of washed blood cells through 3 micron Nuclepore membranes.

This study was designed to investigate a method of analysis which can quantitate the contribution of white cells to the flow of washed suspensions of blood cells. Such an analysis would obviate the need to remove white cells when studying the filterability of normal and abnormal red cells. The flow of suspensions of washed blood cells through a 3 micron Nuclepore membrane declines continually due to the occlusion of pores and the degree of pore occlusion is reduced significantly by the removal of the 'buffy coat' during the preparation of the suspension. These findings are in complete agreement with many other reports. However, a detailed kinetic analysis of the results suggests strongly that the white cell population makes a small contribution to the degree of pore occlusion which is caused largely by approximately 1% of the total red cell population. Despite the phenomenon and extent of pore occlusion, a kinetic analysis of the complete non-linear flow profile allows a measure of the deformability of red cells from filtration studies of washed but unfractionated blood cells.

Effective iron chelation following oral administration of an isoniazid-pyridoxal hydrazone.

When isoniazid and pyridoxal are mixed in equimolar quantities a hydrazone is formed which is able to complex with iron. The oral administration of this compound to rats in single doses of 25--100 mg/kg leads to an increase in faecal iron excretion up to 8 times the normal level. In tissue culture the compound is able to remove iron from Chang cells. The results suggest that this compound may be of potential value for the oral therapy of iron overload.

Light and electron microscope studies of the rat digestive tract following prolonged and short-term ingestion of chrysotile asbestos.

Rats were fed diets containing 0.5 mg or 50 mg of chrysotile asbestos each day for 1 week or 14 months and tissues of the gastrointestinal tract were examined by light and electron microscopy. At the light microscope level the oesophagus, stomach and caecum in treated animals appeared unaffected, whereas accumulation of cellular debris and Alcian blue-positive material was apparent in the ileal, rectal and colonic lumens. Electron microscope examination of the colon and ileum of rats ingesting 50 mg chrysotile/day for 14 months confirmed these findings and indicated changes in the mucosal lining cells of the ileum which were consistent with a mineral-induced cytotoxicity. These results are compared with those reported in a similar previous biochemical study and the specificity of asbestos action on certain regions of the gastrointestinal tract is discussed.

Intracellular iron transport in rat intestinal epithelium: biochemical and ultrastructural observations.

Iron absorption by the rat intestinal epithelial cell has been studied by differential centrifugation of mucosal homogenates and by electron microscopic autoradiography. Autoradiography of both subcellular pellets and whole gut confirmed the biochemical findings. Mitochondria play a quantitatively significant role in iron metabolism within the epithelial cell but do not take part in the transport of iron across the cell during iron absorption.