[Behaviour of thymus mast cells in the rat under various experimental conditions].

The distribution and the histochemical characteristics of the mastocytes of the thymus of postpuberal rats have been studied, in different experimental conditions (control, castrated, castrated and treated with testosterone propionate). The obtained results may be summarized as follows: 1) The mastocytes are located in the thymic capsule and in the connective septa. Among the parenchymal cells, mastocytes have been never observed. 2) In the thymus of castrated rats the total number of mastocytes is statistically significantly reduced. 3) In the thymus of the rats castrated and treated with testosterone, the total number of the mastocytes, in comparison to the castrated rats, increases in a statistically significant way. 4) No evidence has been found of a genesis of mastocytes from the parenchymal thymocytes.