Karyometric and electron microscopic studies of dark and light cells of the adrenal cortex in mammals

The purpose of this study is a comparative study of dark and light cells of cortical parenchyma of the adrenal glands in mammals using light and electron microscopy. Material and methods. Cariometric and electron microscopic studies of the adrenal glands of 9 mammalian species have been carried out: Vulpes vulpes (fox), Vulpes lagopus (arctic fox), Canis familiaris (dog), Мartes zibellina (sable), Mustela vison (mink), Enhydra lutris (sea ape); Castor fiber (river beaver); Callorhinus ursinus (fur seal); Ovis aries (sheep). Serial paraffin sections were stained with hematoxylin and eosin, iron hematoxylin, Heidenheim azan, the PAS-reaction was used, the color of the trichrome-PAS and the tetrachromium-PAS. RNA was detected by the reaction of Brashe and gallocyanin by Einarsson. For the detection of lipids, frozen sections were stained with Sudan III + IV, Black Sudan. The number of dark and light cells in the cortex of the adrenal mink in different seasons was determined. On electron micrographs, the amount of lipid droplets and mitochondria in the fascicle of the adrenal cortex was counted. Results. In the cortex of the adrenal glands of mammals, dark and light cells are present. Dark cells, as far as accumulation of sudanophilic substances are converted into light cells, which with further accumulation of lipids undergo destructive changes. Also found are the dark dying cells of the adrenal cortex, characterized by densification of the cytoplasm, pycnosis of nuclei, accumulation of yellow-brown pigment. Dark cells have larger nuclei, give more intense reaction to RNA and ketosteroids and are more active secretory cells compared to light adrenocorticocytes. Electron microscopy in dark cells reveals a large number of mitochondria and a significant amount of lipid droplets are present. Light cells contain many lipid inclusions and few mitochondria.

Rehydration of high-density sickle erythrocytes in vitro

Recent studies have identified older, low-density sickle red blood cells (SSRBCs) that were resistant to dehydration by valinomycin, a K+ ionophore. These cells, thought to derive from dense SSRBCs that have rehydrated, may represent a terminal cellular phase. To study rehydration, we subjected dense SSRBCs (ρ > 1.107 g/cc) to either oxygenated incubation or rapid oxygenated/deoxygenated (oxy/deoxy) cycling (70 seconds per cycle). Light cells (ρ < 1.087 g/cc) were generated during both oxy incubation (2.9% ± 2.1%; n = 42) and oxy/deoxy cycling (5.3% ± 2.4%; n = 42). The rehydrated cells were K+-depleted (K+ = 20 ± 14 mmol/kg hemoglobin [Hb]) and Na+-loaded (Na+ = 394 ± 106 mmol/kg Hb), and had high levels of external phosphatidylserine. In the presence of external calcium, the generation of rehydrated SSRBCs was inhibited during oxy/deoxy cycling, but the percentage with external phosphatidylserine increased. The calcium-mediated inhibition of rehydration was reversed by charybdotoxin, implying that rehydration was delayed in some cells by the Ca++-activated K+ channel. Preincubation of dense SSRBCs with DIDS (4,4′-di-isothiocyanato-2,2′-disulfostilbene) inhibited the generation of light cells during fast oxy/deoxy cycling, but not during oxy incubation. These results suggest that the sickling-induced pathway, previously implicated in SSRBC dehydration, may be involved in the deoxy-dependent component of rehydration for dense, K+-depleted cells. Light-cell generation was inhibited by 1 mM bumetanide during both oxy incubation and oxy/deoxy cycling, providing evidence that a bumetanide-sensitive, deoxy-independent pathway, previously described in circulating light SSRBCs, also contributes to the rehydration of high-density SSRBCs.

K(+)-Cl- cotransport and volume regulation in the light and the dense fraction of high-K+ dog red blood cells

We examined a chloride (Cl-)-dependent K+ transport (K(+)-Cl- cotransport) and regulatory volume decrease in dog red blood cells with high K+, low Na+, and high glutathione (GSH) content (HK/HG) due to the presence of an Na(+)-K+ pump. The HK/HG cells were separated according to their density, and the age-marker enzyme activities, such as glucose-6-phosphate dehydrogenase and cholinesterase, were determined. Unexpectedly, we found that young cells were heavier (more dense) and smaller in size compared with the old cells, which were lighter (less dense) and larger. The K(+)-Cl- cotransport was nearly 10-fold higher in the most dense cells, representing a 12% fraction of the total population compared with the lightest cohort. Although K(+)-Cl- cotransport in both the dense and the light cells was activated by N-ethylmaleimide, swelling and depletion of cellular divalent cations and the activation of the transport in the dense cells was greater. Both the dense and light cells regulated their volume when they were isosmotically swollen. Therefore, the lower activity of K(+)-Cl- cotransport might not explain the relative large volume in old HK/HG cells. The concentration of GSH and glutamate was higher in the light cells. Thus the higher the GSH and glutamate concentration, the greater the cell volume and the lower the K(+)-Cl- cotransport.

Presence of Both Hemidiscoidal and Hemiellipsoidal Phycobilisomes in a Phormidium Species (Cyanobacteria)

Hemidiscoidal and hemiellipsoidal phycobilisomes have been determined in cells of the complementary chromatically adapting cyanobacterium Phormidium sp. C86 . They could be isolated from red and green light-adapted cells, respectively. Hemidiscoidal red light phycobilisomes show molar pigment ratios of allophycocyanin: phycocyanin of 1:4.5 with phycoerythrin lacking. Hemiellipsoidal phycobilisomes induced by green light present allophycocyanin: phycocyanin: phycoerythrin ratios of 1:1:6.8. The differences between the two phycobilisome types could additionally be demonstrated by their ultrastructure and sedimentation values. Isolated red light phycobilisomes have six rods, show dimensions of 70×30×15nm and a sedimentation value of 66 S whereas green light phycobilisomes are nearly twice larger. They contain ten rods and present dimensions of 70×40×25nm and a sedimentation value of 98 S. The number of phycobilisomes in red light cells is almost twice as large as in green light cells. There is evidence that cells grown under white light contain both types as well as “intermediate” forms.

Cytological Differences in the Localization of Glucocorticoid Receptor-Like Imnunoreactivity in the Normal and Transplanted Pituitary Pars Intermedia

Glucocorticoid receptor-like immunoreactivity (GCRI) was found in the normal pituitary pars intermedia (PI) when immunohistochemistry was used. Since in previous studies we described two kinds of cells in the denervated (grafted) PI, i.e., “light cells” (overactive cells which do not contain detectable melanocyte stimulating hormone) and “dark cells” (hypoactive cells which contain the hormone), it was decided to investigate whether different patterns of distribution of the receptors could be detected in the grafted gland when compared with the intact PI. Intact glands showed the receptors located in the nucleus. In transplanted glands, it was observed that light cells showed receptors in both the nuclei and the cytoplasm; on the other hand, dark cells displayed them in the nuclei only, as is the case in all cells of the normal PI.We had previously interpreted dark cells as dopamine-indifferent, whereas light cells were considered dopamine-sensitive. The changes in the distribution of GCR after denervation by grafting, which only affected the light cells, support the view of other authors that GCR of. the pars intermedia are under the influence of dopamine and reinforce our opinion that dark cells are dopamine-indifferent