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.

Heterogeneity of the cartilage-marrow interface during uncalcified cartilage resorption in the chick embryo tibia.

The morphology of the cartilage-marrow interface in chick embryo tibiae has been studied from Day 11 to Day 14. The cartilage-marrow interface did not present a uniform aspect and three different areas could be defined. Most of the interface was lined by fibroblast-like cells, macrophage-like cells and multinucleate giant cells.

Morphometric study of cartilage dynamics in the chick embryo tibia. II. Dexamethasone-treated embryos.

The cartilage dynamics in the tibia of dexamethasone-treated chick embryos has been studied by means of morphometric methods. Treated embryos showed a delay in the longitudinal growth of the tibia, as well as in the growth of all structures enclosed by the perichondrium-periosteum. The cartilage formation rate remained nearly unchanged (above 1 mm3/day) from Day 12 to Day 14, whereas the cartilage resorption rate was zero up to Day 13, and showed a non-significant increase from Day 13 onwards.

Morphometric study of cartilage dynamics in the chick embryo tibia. I. Methodology and tissue compartments in normal embryos.

Cartilage dynamics during the development of the chick embryo tibia has been studied by means of morphometric methods, from the 11th to the 14th days. The volume densities of the structures enclosed by the perichondrium-periosteum did not change significantly through the age span studied, whereas the absolute volumes of these structures increased during the whole period under investigation. The cartilage volume showed the most rapid increase from Day 12 to Day 13 (by a factor of x1.

Effects of neonatal estrogenization on rat bone development: a histomorphometric study.

The effects of a single dose of 500 micrograms of estradiol benzoate, administered on the first day of life, on rat bone development have been histomorphometrically studied at 15 days of age. Estrogenized animals presented decreased total tibial length (16.55 +/- 0.