A single 12 mg dose of stilboestrol dipropionate given to 100-day-old male rats resulted in increased pituitary mitotic activity, pituitary weight and serum growth hormone; the latter rose from a mean value of 20 ng/ml to a maximum of 342 ng/ml 9 days later. Serum growth hormone and pituitary mitotic activity then gradually diminished but were still slightly increased on day 28. Serum growth hormone and pituitary weight were significantly correlated during the periods of rapidly rising and of sustained high levels of serum growth hormone. Indices of mitotic activity were correlated with serum growth hormone during the periods of rapidly rising and of falling levels of serum growth hormone.

1.As experimental models of reduced nephron population in man, (a) twelve men aged 15-32 years who had one kidney removed 1-13 years previously and (b) fourteen normotensive men aged 70-90 years were studied. Results were compared with those in eighteen normotensive men aged 18-28 years and eleven men aged 19-33 years with essential hypertension.2. While the subjects followed a routine of normal diet and daily activity, measurements were made, after overnight recumbency and in the fasting state, of plasma volume and renin activity on one occasion in hospital and of blood pressure on five to fourteen occasions in the home. Blood pressure was also measured after standing for 2 min and plasma renin activity after I hstanding, sitting or walking. Twentyfour hour urinary aldosterone excretion was also measured.3. The measurements were repeated in the normotensive subjects and subjects in (a) and (b) above after 10 days of sodium-restricted diet (40 mmol of sodium/day).4. The mean plasma renin activity (recumbent) in essential hypertensive subjects was higher than in normotensive subjects. In subjects of (a) and (b) above, it was lower than normotensive subjects, and was not increased by dietary sodium restriction in subjects of (a). 5. The mean aldosterone excretion level was lower in old normotensive subjects than in the other groups, and increased in each group after dietary sodium restriction.6. Mean plasma volumelsurface area was not Correspondence: Dr R. D. Gordon, Department of Medicine, Repatriation Hospital, Greenslopes, Queensland 4120. Australia.different between the four groups and in normotensive, essential hypertensive and nephrectomized subjects but not subjects aged 70-90 years was negatively correlated with standing diastolic blood pressure.

Following β-glucuronidase hydrolysis, pregnanetriol, pregnanetriolone and tetrahydro S were extracted from urine, chromatographed on florosil and in two paper systems before semiquantitative estimation of pregnanetriol and pregnanetriolone with the phosphoric acid reaction and of tetrahydro S with blue tetrazolium. The chemical validity and reliability of the method were studied and excretions measured in normal subjects and endocrine disorders. Pregnanetriol excretions were compared with published values. Normal pregnanetriol excretions were found in »idiopathic« hirsutism, with Stein-Leventhal ovaries and in Cushing's syndrome due to adrenal adenoma and hyperplasia; increased excretions were found in congenital adrenal hyperplasia and Cushing's syndrome with adrenal carcinoma. Pregnanetriolone was detected only in congenital adrenal hyperplasia, Cushing's syndrome from hyperplasia and one carcinoma. Large amounts of tetrahydro S were found in Cushing's syndrome with adrenal carcinoma. The possible diagnostic significance of the findings is discussed.

Summary Tissue culture of slices of polycystic ovaries shows that androstenedione and oestradiol are mostly produced by the cortical, cyst‐containing portions, with little steroid production in vitro by medullary stromal tissues.