G. D. Thorburn

Prostaglandins in the circulation of the fetal lamb.

Prostaglandin E and PGF have been measured in the plasma of chronically catheterized fetal lambs throughout the last 20-35 days (0.73 onwards) of gestation. The mean concentration of PGE was higher than that of PGF. There was a significant increase in the concentration of PGE but little change in the concentration of PGF in samples of fetal plasma taken within 24 h of parturition. In contrast, at this time in maternal utero-ovarian venous plasma, there was a large increase in PGF, but relatively little change in PGE. There was a significant decrease in the concentration of PGE and PGF in the plasma of lambs within 12 h after birth compared to the levels found in the same animals as fetuses a few hours previously. The physiological importance of these changes is discussed.

Effects of Danazol on Pituitary Gonadotrophins in Post-Menopausal Women

Summary: Multiple sampling was carried out in 4 postmenopausal women for measurement of LH and FSH before and at the end of a 1‐week treatment period with Danazol (400 mg daily). A small but significant depression of FSH was found in 3 of 4 subjects, while a significant depression of LH was only seen in 1 subject. In view of the very modest gonadotrophin suppression demonstrated in these women it is possible that Danazol also exerts its profound and sometimes rapid effects through inhibition of positive oestrogen feedback and by direct actions on the ovaries and endometrium.

Immunocytochemical localisation of prolactin and growth hormone in the perinatal sheep pituitary

SummaryThe peroxidase anti-peroxidase immunocytochemical staining technique has been used to identify prolactin and growth hormone cells in pituitaries from fetal and neonatal sheep. The size of the secretory granules in these cell types has been measured using the image analysing computer Quantimet 720. The area size distributions of the fetal prolactin and growth hormone granules were compared with those in the neonate and the adult. It appears that the gestational age of the fetus may influence the size range of prolactin secretory granules.

Influence of danazol treatment during the luteal phase on pituitary and ovarian function during the subsequent menstrual cycle**Supported in part by grants from the Australian National Health and Medical Research Council and Sterling-Winthrop Pty. Ltd., Sydney, New South Wales, Australia.

Eight subjects with normal menstrual cycles were treated with danazol (800 mg daily) during one luteal phase to assess the effect on follicular development in the subsequent cycle. Plasma levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, and progesterone were measured daily throughout both cycles. Following danazol there was a consistent and significant delay to the preovulatory estradiol (P less than 0.05) and LH (P less than 0.02) peaks and a significant suppression of the early follicular phase FSH (P less than 0.05) and preovulatory estradiol peak plasma levels (P less than 0.05). All other parameters of the post-danazol cycle were indistinguishable from normal. However, there was a small suppression of midluteal phase FSH during danazol treatment, compared with the posttreatment cycle, which was significant for three subjects. It is suggested that the small effect of luteal phase danazol on subsequent follicle development may occur at an intraovarian level through an effect on receptors or enzymes as well as through the small degree of suppression of midluteal phase and early follicular phase FSH.