OBJECTIVE: To determine whether immature spermatids increase in semen in response to hormonal contraceptive treatments. Such a finding would support the existence of a defect in spermiogenesis, which in turn may explain the reported variability in sperm output. DESIGN: Semen smears were obtained ...

This is a pilot dose-finding study of spermatogenic suppression using testosterone undecanoate (TU) injections alone in normal Chinese men. Thirty-two healthy men were recruited. Volunteers underwent pretreatment evaluation, then a treatment period in which group I (n = 13) received 500 mg TU, group ...

Germ cell and Sertoli cell numbers were estimated in six normal adult monkeys (Macaca fascicularis) using a contemporary unbiased and efficient stereological method--the optical disector. The data was used to assess the efficiency of spermatogenesis from type B spermatogonia to elongated spermatids. ...

OBJECTIVE: To assess the pituitary responsiveness to GnRH stimulation of premenopausal women relative to age. DESIGN: Older and younger reproductive-age women underwent the GnRH stimulation test in the early follicular phase of the menstrual cycle. SETTING: Female subjects in an academic research ...

OBJECTIVE: To investigate changes in menstrual cycle hormones and endometrial maturation that may contribute to the decline in fertility with aging. DESIGN: Prospective controlled clinical study. SETTING: Normal human volunteers in an academic research institution. SUBJECTS: Women with regular ...

Studies using high dose testosterone (T) administration in normal men as a male contraceptive have resulted in azoospermia rates of only 50-70%. Previous studies of T and progestogen combinations have shown comparable rates of azoospermia, but have been uncontrolled or used T in doses less than ...

Follistatin is an activin-binding glycoprotein that decreases FSH secretion in vitro and in vivo in rats. The mechanism by which follistatin acts is unclear, but it has been suggested that it may bind endogenous activin and neutralize its effects. In this study, we wished to test the ability of ...

7alpha-Methyl-19-nortestosterone (MENT) is a potent synthetic androgen that cannot be converted to dihydrotestosterone. In this study we determined the relative androgenic, antigonadotropic, and anabolic potencies of testosterone vs. MENT in the nonhuman primate M. fascicularis. In castrated monkeys, ...

Inhibin is a gonadal glycoprotein believed to be important in the regulation of pituitary FSH secretion and/or to function as a paracrine factor within the ovary and testis. We studied serum levels of inhibin, oestradiol (E2), progesterone (P), FSH and LH during the periovulatory interval in order ...

No effective hormonal contraceptive has yet been devised for men. Through their suppressive effect on gonadotropin secretion, GnRH antagonists inhibit both testosterone (T) production and spermatogenesis in animals. Long term administration of an antagonist alone would result in androgen deficiency; ...