• Evidence of impaired fertility in the male was found in nearly half of the infertile couples studied. Most of the infertile men were entirely normal as to body contours and other usual criteria of virility. No significant differences were found in a comparison of subfertile and azoospermic men with men of known fertility as to the fructose content of the semen and the urinary excretion of 17-ketosteroids. Paper chromatography revealed an unexplained difference between azoospermic men and the other two groups as to the distribution of amino acids in the seminal plasma. While in the cases of infertility the etiology in general was obscure, pregnancies followed in several instances of insemination with ejaculates concentrated by a special technique.
Tyler ET, Singher HO. MALE INFERTILITY—STATUS OF TREATMENT, PREVENTION AND CURRENT RESEARCH. JAMA. 1956;160(2):91-97. doi:10.1001/jama.1956.02960370001001