Despite a considerable amount of investigation there continues to be disagreement concerning the proteins present in human seminal plasma. Recently their identification has assumed a greater importance following evidence that infertility in men and women may have an immunological cause (Katsh, 1959; Quinlivan, 1969). Seminal plasma is composed of fluids secreted by the prostate, seminal vesicles, ampullae, ducti deferentes, bulbourethral (Cowper s) glands, urethral(Littre s) glands and the epididymes. Prostatic juice, one of the major components of seminal plasma, has an important role in secretion of acid phosphatase and prostaglandin. A few studies have been reported of human prostatic juice, since, in human subjects, there were some problems in studying prostatic juice due to quite small amount of secretion and possibility of contamination with fluids from the seminal vesicles and ejaculatory ducts. The purpose of the present study was to determine the basic components of proteins in human prostatic juice. Prostatic juice was obtained from normal healthy man of 20 ~ 30 year-old by massage of the prostate, and protein components were separated by means of disc electrophoresis. The results are summarized as follows; 1) Total numbers of protein fractions of normal human serum and prostatic juice are 14 ~ 18 bands and 9 ~ 12 bands, respectively. Prostatic juice produces two deeply staining bands which appear similar to those formed by beta-1 globulin and albumin. 2) Alpha-1 globulin area in the fractions of prostatic juice shows 4 bands and one more band is found than that of serum. On the other hand, the fractions of immunoglobulin and alpha-2 globulin areas are eight in serum and it has three bands more than that of prostatic juice. 3) Alpha-1 globulin area in the prostatic juice is more deeply stained than that of serum. In contrast with alpha-1 globulin area, immunoglobulin and alpha-2 globulin areas in the prostatic juice show weaker staining than serum.
