The Two Components of Semen 19 



rather high content of zinc. The first to observe this, and to comment 

 on the possible role of zinc in reproduction, was Gabriel Bertrand; 

 in the two analyses of human prostate carried out by Bertrand and 

 Vladesco (1921) there was found 9-4 and 11-3 mg. Zn per 100 g. 

 fresh tissue, or 49 1 and 53 1 mg. Zn per 100 g. dry weight. More 

 recently, Mawson and Fischer (1951, 1952, 1953) in Canada, found 

 that the mean zinc content of the human prostate gland was 68-2 mg. 

 Zn/100 g. dry wt., which is in considerable excess of zinc content 

 in human liver, muscle, brain, testis or blood. These investigators 

 state that the zinc present in the human seminal plasma is derived 

 chiefly from the prostatic secretion. 



A considerable number of studies have been carried out with the 

 rat prostate (Fig. 4). In the rat, there is a distinct anatomical and 

 functional difference between the so-called ventral prostate which 

 secretes only citric acid, and the dorso-lateral prostate which pro- 

 duces both citric acid and fructose (Humphrey and Mann, 1948, 

 1949). In the dorso-lateral prostate itself, however, it is possible 

 to distinguish three smaller regions, the dorsal or median portion 

 which does not contribute citric acid, and two lateral lobes which 

 are rich in citric acid (Price, Mann and Lutwak-Mann, 1949). It is 

 the dorso-lateral prostate, and more specifically, its two lateral lobes 

 which contain much more zinc than any other soft tissue of the rat, 

 and which at the same time exhibit carbonic anhydrase activity 

 almost equal to that of blood (Mawson and Fischer, 1952); whereas 

 however, the carbonic anhydrase in the rat lateral prostate accounts 

 for no more than one-tenth of the total zinc content, in blood 

 erythrocytes this enzyme is well known to correspond closely to 

 the bulk of the zinc content (KeiUn and Mann, 1940). 



The protein content of the prostatic secretion is low, less than 1 % 

 in man, and a certain proportion of the protein-like material present 

 in the secretory fluid is composed of 'proteoses' which are not preci- 

 pitated by trichloroacetic acid. Another feature of the prostatic 

 secretion is its elevated content of certain free amino acids, the 

 presence of which is probably the outcome of a combined action 

 of proteolytic and transaminating enzymes in the glandular tissue 

 (Barron and Huggins, 1946a; Awapara, \952a, b). Human prostatic 

 adenoma contains in 100 g. tissue 50 to 200 mg. glutamic acid in 

 addition to several other amino acids. The average content of amino 

 3 



