Neonatal exposure of male rats to estradiol benzoate causes rete testis dilation and backflow impairment of spermatogenesis.

Estrogens administered to perinatal rodents cause spermatogenesis impairment; this study was undertaken to determine the mechanisms by which estrogens exert this effect. Neonatal male Wistar rats received estradiol benzoate (either 0.5 mg/5g BW or 1 mg/5g BW) and were killed at days 10, 22, 33, 45, and 60.

Simultaneous proliferation and differentiation of mast cells and Leydig cells in the rat testis. Are common regulatory factors involved?

The proliferation and differentiation of mast cells and Leydig cells were studied in adult sham operated or hypophysectomized rats after the administration of ethylene dimethane sulphonate (EDS) and in prepubertal rats after neonatal treatment with a gonadotropin-releasing hormone (GnRH) antagonist (Organon 30276; Oss, The Netherlands). After treatment with EDS, two proliferative waves were found. On day 3, several interstitial cell types proliferated, whereas mitotic cells corresponded to differentiating Leydig cells and mast cells around day 20.

Estrous cycle-related changes in mast cell numbers in several ovarian compartments in the rat.

The absolute number of mast cells in several ovarian compartments was studied during the estrous cycle of the rat. The number of mast cells significantly increased on proestrus (either in the morning or in the evening) in the ovarian medulla and cortex, whereas no significant changes were found in the ovarian bursa. During proestrus, abundant mast cells were present in the bursal cavity along with eosinophil and mononuclear leucocytes.

Are eosinophil leucocytes involved in the oestrogenic response of the postnatal rat epididymis?

The effects of oestrogens and androgens, alone or in combination, on several epididymal parameters have been studied in 15-day-old rats after neonatal treatment. Oestrogens induced several responses, such as increased growth of the fibromuscular stroma and eosinophil leucocyte accumulation, whereas the proliferative activity of the epithelium was decreased significantly. Otherwise, the density of intra-epithelial leucocytes was not modified.

Leydig cell involvement in the paracrine regulation of mast cells in the testicular interstitium of the rat.

The accumulation of mast cells in the rat testicular interstitium was studied under different experimental conditions in order to correlate this accumulation with the alterations of specific testicular tissue compartments or cell types. Estrogen treatment was effective in inducing mast cell proliferation when administered on Day 1 or at higher doses at 10 days of age. Estrogens were ineffective beyond 20 days of age.