Morphological and enzyme-histochemical changes of the mouse thymus after hydrocortisone

Nuclear localization of gold labeled-hydrocortisone-bovine serum albumin conjugate injected intravenously into the hormone-target cells of rat

We have suggested in a previous study using 2-nm colloidal gold labeled-testosterone-bovine serum albumin (testosterone-BSA-gold) that 2-nm gold labeled-steroid hormone-BSA conjugates would be a useful tool for analyzing the mechanism of steroid hormone action (39). In this study, we examined whether hydrocortisone-BSA conjugate (hydrocortisone-BSA) showed a similar distribution to radiolabeled hydrocortisone in vivo, by injecting 2-nm colloidal gold labeled-hydrocortisone-BSA (hydrocortisone-BSA-gold) into the rat tail vein. The hydrocortisone-BSA-gold with silver enhancement became visible as silver deposits under electron microscopy in the nuclei of hepatocytes and hepatic stellate cells but not in Kupffer cells in the liver, and in the thymocytes and thymic reticuloepithelial cells in the thymus of a rat killed 2 h postinjection. The percentage of nuclei showing deposits in the non-target cells, the epithelial cells of the seminal vesicle, was similar to the value in the seminal vesicle of a control rat injected with BSA labeled with 2-nm colloidal gold as reported previously. In the hepatocytes and thymocytes of a control rat not injected, the percentages of nuclei showing deposits were similar to those in the rat injected with testosterone-BSA-gold or BSA-gold as reported previously, but lower than those in the rat injected with hydrocortisone-BSA-gold. These results suggest that hydrocortisone-BSA-gold is useful for the morphological study of hydrocortisone target cells, and imply that BSA conjugated with hydrocortisone can enter the target cell nuclei of the rat. The present study further indicates that the fate of gold labeled-steroid hormone-BSA conjugates may be decided at the cell membrane level.

Effects of hydrocortisone on the ultrastructure of the thymic cysts of the chick embryo

Thymi from 80 19-day chick embryos that were injected with 2.5 mg of hydrocortisone on the 15th day of incubation were examined by light and electron microscopy. Six thymic tissue blocks from each embryo were evaluated. Hydrocortisone caused a marked depression of thymic volume due mainly to the depletion of lymphocytes. Cystic structures, consisting of intercellular and intracellular cysts and individual cystic cells, were more numerous per unit area of medullary tissue in treated embryos than in the controls. In the treated group, the shape of cystic cells varied from squamous to columnar, and hypertrophied columnar cells were also evident. The luminal surface possessed well-developed microvilli with membrane invaginations at their bases. The terminal web was prominent and the lateral plasma membranes were highly interdigitated. The rough and smooth-surface endoplasmic reticula and the Golgi complex of thymi from treated embryos were more developed than those in the controls. Mitochondria and vesicles were increased in number following hydrocortisone treatment. Cysts lined partially by cystic and endothelial-like and smooth muscle cells were encountered in the treated group. These structural modifications probably reflect responses to increased absorptive or transport function. The data suggest that hydrocortisone may alter the structure of cystic cells in chick embryos.

Dexamethasone-induced changes in morphology and keratin organization of rat thymic epithelial cells in primary culture

Dexamethasone (DM)-induced changes in morphology and keratin organization of rat thymic epithelial cells (TECs) in primary culture were studied. The morphology and keratin organization of TECs were greatly altered by the addition of more than 10 nM DM. In control cultures, small slender cells were predominant and grew faster than cells of other types. Most of them had keratin bundles on day 3, but lost the bundles on day 7. In experimental cultures containing more than 10 nM DM, the morphology of TECs altered to a polygonal form and the TECs formed colonies. They had fine interlacing bundles of keratin filaments all over the cytoplasm, and the bundles were maintained or increased in number with the day of culture. Keratin proteins in TECs treated with 100 nM DM for 7 days were 2-fold for 46 500 D, 4-fold for 49 000 D, 1.7-fold for 52 000 D and 3.5-fold for 55 500 D keratins to those in control TECs, respectively. Growth of TECs was inhibited by the addition of more than 10 nM DM. The effects of DM were reversible to some extent, for the morphology and keratin organization of TECs gradually changed into the control type by the removal of DM. These results suggested that DM greatly involved the growth and differentiation of rat TECs.

The ANAE reaction pattern of reticular stromal cells of lymphatic organs from normal and hydrocortisone--treated mice

The pattern of alpha-naphthyl-acetate esterase (ANAE) activity in stromal and lymphatic cells has been examined in lymphatic organs from normal and hydrocortisone (HC)-treated mice. The distribution of ANAE-positive lymphocytes as well as stromal cells in peripheral lymphatic organs was different in T- and B-dependent regions, while in the thymus there was the difference between cortex and medulla. The HC application evoked a marked changes in the pattern of ANAE-positive cells distribution of the thymus, producing only a slight ones in the remaining organs. The influence of HC on the ANAE reaction intensity and distribution in the examined tissue sections is discussed.

Short time observations of morphological changes and cholinesterase distribution in lymphatic organs of the mouse after corticosteroid and X-ray treatment

The changes in thymus, spleen and lymph nodes of the mouse after a single cortisone application or a single whole body x-irradiation were investigated morphologically and histochemically. During 24 h the alterations following the cortisone application are at all stages examined indistinguishable from those following the x-irradiation. The first signs of lymphocyte destruction can be observed already in the first two hours after treatment. Almost at the same time macrophages accumulate at the sites of cell death in the lymphatic organs studied. The eosinophils display a different behaviour. While they accompany the macrophages in the thymus already at the first stages, they appear in the spleen and lymph nodes with a latency of 6 and 8 h, respectively. The highest amount of necrotic cells is found ten hours after both treatments. At the same time the accumulation of macrophages and eosinophils reaches its maximum. The cholinesterase in the lymphatic organs is largely the true cholinesterase. The enzyme-activity increases in the cortex of the thymus gradually 6 h after treatment, showing the highest deposit of reaction product at 10 h. In spleen and lymph nodes the cholinesterase shows only slight variations. The possible role of the cholinesterase-activity in these non-cholinergic tissues is discussed.