Endocrine parameters were assayed in a San ("Bushman") population of Botswana in an attempt to correlate hormonal secretion and body morphology. Serum levels of gonadotrophins and gonadal steroids were measured by employing radioimmune methods. No evidence for elevated estrogens could be found and males showed endocrine levels comparable with European and South African Negro values. Females have suppressed circulating levels of gonadal steroids and little corpus luteum function. A mechanism by which the ovaries may be suppressed, thereby limiting conception to times of high nutrition, may exist in the San. This hypothesis may have a bearing on the observation that births reach peak levels during March and April.

SUMMARY. The content of cytoplasmic 17~oestradiol and progesterone receptors in human uterine leiomyoma and normal myometrium in the Negroid population was determined. Eighteen women of reproductive age. at various stages of the menstrual cycle. were included in the study. The serum oestrogen and progesterone concentrations were also measured. This is the first report in the literature in which oestrogen and progesterone receptors in leiomyoma are significantly higher than in normal myometrium (P=().()002). The steroid dependence of the growth of leiomyomas may be related to the steroid receptor level. The presence of persistently high concentrations of oestrogen and progesterone receptors in leiomyoma should be helpful in the treatment of this benign tumour.Leiomyoma of the uterus is the most common solid pelvic benign tumour in the female and occurs in nearly 20'Yo of all women during reproductive life.' The tumour increases in size during pregnancy or in response to exogenous oestro~en and regresses following menopause. -I For unknown reasons the incidence is much higher in the Negroid population than in Caucasians. I. 5. h Sufficient data are not available at present to suggest any conclusion regarding the aetiology of uterine leiomyomas. Nevertheless. it seems that leiomyomas arise from a single neoplastic parent cell derived from the smooth muscle elements of the myometrium and the growth of cells is influenced by various factors in the cellular environment. including the effect of steroid borrnones.""The concentration of oestrogen and progesterone receptors in human uterine leiomyoma and normal myometrium were measured in an attempt to clarify the relation of receptors to tumour growth in the Negroid population. We have also studied the concentrations of serum 17~oestradiol and progesterone with respect to steroid receptor concentrations in leiomyoma and normal myometrium at different phases of the menstrual cycle. Materials and methods PATIENTSEighteen women were included in the study. Each of these women had a hysterectomy for leiomyoma at Baragwanath Hospital. Criteria for patient selection included reproductive age, history of regular menstrual cycles and no history of exogenous hormone usage.The menstrual cycle dating was done by last menstrual period. by histologic evaluation of the endometrial specimen and serum progesterone levels. On the day of the operation a venous blood sample was obtained, allowed to clot and centrifuged. Serum was separated and frozen at -20°C. REAGENTSThe radioligands (2. 4, 6, 7 3H(N)) 17~oestra-diol, specific activity 95 Ci/rnmol. and 171~ methyl-3(lI)prornogesterone .263