Secretions of the Testis and Epididymis
SECRETIONS OF THE TESTIS AND EPIDIDYMIS B. P. SETCHELL Biochemistry Department, A.R.C. Institute of Animal Physiology, Babraham, Cambridge In recent years, it has become apparent that the testis produces, in addition to the androgens, considerable amounts of another type of secretion which flows from the lumina of the seminiferous tubules through the rete testis into the epididymis. Here a large part of the fluid part of the secretion is reabsorbed, but additional compounds are added as the spermatozoa pass down the epididymal duct. In this paper, attention will be largely confined to the most recent findings concerning this latter secretion, as the earlier observations have been reviewed by Setchell (1970a) and Setchell & Waites (1971). Rate offlow and ionic composition The fluid which flows from the rete testis of all species so far examined (ram, bull, boar, rat, hamster, wallaby) is a low-protein fluid, isotonic with plasma but containing about three times as much potassium, less sodium and bicarbonate and more chloride than plasma or testicular lymph. The fluid leaves the testis at a rate of between 10 and 20 \g=m\l/g testis/hr, i.e. about 40 ml/day from a 200-g testis of a ram (Voglmayr, Scott, Setchell & Waites, 1967), but to keep these figures in proportion it should be remembered that this rate of flow is exceeded five- to tenfold by the flow of lymph from the testis (Lindner, 1963; Cowie, Lascelles & Wallace, 1964) and 1000-fold by the flow of blood through the testis (Setchell & Waites, 1964). Fluid leaves the rete testis continually and at a steady rate and normally contains between 0-3 and 1 IO6 spermatozoa/ml.
[Show full text]