MAMMALIAN TESTIS 



353 



crinologists. jMany unsuccessful attempts 

 have been made to induce precocious sperm 

 formation in the rat by chronic or massive 

 use of various gonadotrophins. The time of 

 a complete spermatogenic cycle is not ac- 

 curately known. Estimates ranging from 20 

 to 40 days have been given, which reflects 

 the difficulties and errors of present meth- 

 ods. If one adds to the time at which sperm 

 formation normally occurs in common 

 strains of the laboratory rat (around 35 

 days of age ) , about 10 days borrowed from 

 fetal life, the time of a complete spermato- 

 genic cycle is probably between 45 and 

 50 days. Hence, no amount of exogenous 

 gonadotrophin could be expected to produce 

 precocious spermatogenesis, because a cer- 

 tain irreducible minimum of time may be 

 recjuired for the series of divisions which in 

 toto constitutes a spermatogenic cycle. 

 However, if the interval between birth and 

 maturity is much longer than the time of a 

 complete spermatogenic cycle, precocious 

 spermatogenesis could be experimentally 

 achieved, as is again indicated by an ex- 

 ample from clinical endocrinology, i.e., the 

 spontaneous occurrence of isosexual pre- 

 cocity in boys. 



In another clinical area, the application 

 of quantitative techniques to the study of 

 testes of iKitients afflicted with infertility 

 has so far not yielded helpful information. 

 Restoration of fertility in men with adult 

 seminiferous tubular failure has not been 

 accomplished. Infertility, however, is re- 

 ceiving increasing attention, especially from 

 the standpoint of genie factors. It is in this 

 area that the only startling development of 

 knowledge on the testis in the past 20 years 

 has occurred, i.e., the discovery that men 

 with Klinefelter's syndrome are "genetic fe- 

 males." One may, with good reason, ques- 

 tion the suitability of the term "genetic fe- 

 males." It arose from the application of 

 Barr's discovery of sex dimorphism in the 

 heterochromatin of somatic cells (Barr, 

 1956; Barr and Bertram, 1949; Moore and 

 Barr, 1955) . Normal females are "chromatin 

 positive"; normal males are "chromatin 

 negative." This, however, may not be ab- 

 solute. Men with Klinefelter's syndrome are 

 chromatin positive, and if chromatin posi- 

 tivity reflects genie constitution, it is likely 

 that the sterility of men with this syndrome 



(one of its outstanding features) represents 

 an abnormality of chromosomal division 

 or number during gametogenesis of one of 

 their parents. Generally similar situations 

 may occur in lower animals; hence, the role 

 of genie factors in fertility can be studied 

 experimentally. 



Great advances have taken place in 

 knowledge of the biosynthesis of male hor- 

 mone by the testis. Illumination of the 

 chemical pathway over which simple pre- 

 cursors (acetate) or more complex ones 

 (cholesterol) are transformed to testoster- 

 one represents a major contribution in bio- 

 chemistry. The enzymatic control of the 

 various chemical steps will undoulitedly be 

 disclosed before long. 



XVIII. References 



Albert, A., Underdahl, L. O., Greene, L. F., and 

 LoRENz, N. 1953a. Male hypogonadism. I. 

 The normal testis. Proc. Staff Meet., Mavo 

 Clin., 28, 409. 



Albert, A., Underdahl, L. O., Greene, L. F., and 

 LoRENz, N. 1953b. Male hypogonadism. II. 

 Classification. Proc. Staff Meet., Mavo Clin., 

 28, 557. 



Albert, A., Underdahl, L. O., Greene, L. F., and 

 LoRENZ, N. 1953c. Male hypogonadism. III. 

 The testis in pituitary dwarfism. Proc. Staff 

 Meet., Mayo Clin., 28, 698. 



Albert, A., Underdahl, L. O., Greene, L. F., .\nd 

 LoRENz, N. 1954a. Male hypogonadism. IV. 

 The testis in prepubertal or pubertal gonado- 

 trophic failure. Proc. Staff Meet., Mavo Chn., 

 29, 131. 



Albert, A., Underdahl, L. O., Greene, L. F., .^nd 

 LoRENZ, N. 1954b. Male hypogonadism. V. 

 The testis in adult patients with multiple de- 

 fects of pituitary function. Proc. Staff Meet., 

 Mayo Clin., 29,317. 



Albert, A., Underdahl, L. O., Greene, L. F., .od 

 LoRENz, N. 1954c. Male hypogonadism. VI. 

 The testis in gonadotrophic failure in adults. 

 Proc. Staff Meet., Mayo Chn., 29, 368. 



Albert, A., Underdahl, L. O., Greene, L. F., .\^d 

 LoRENz, N. 1955. Male hypogonadism. VII. 

 The testis in partial gonadotrophic faihne dur- 

 ing puberty (lack of luteinizing hormone onlv). 

 Proc. Staff Meet., Mayo Clin., 30, 31. 



Alcozer, G., and Costa, U. 1954. Comporta- 

 mento delle frazioni colesteroliche nel testicolo 

 di cavia adulta trattata con estratto acquoso di 

 pineale. Arch. "E. Maragliano" pat. e clin., 9, 

 355. 



Alcozer, G., .^nd Giordano, G. 1954. Rapporti 

 epifiso-testicolari ; modificazioni istologiche del 

 testicolo di cavia adulta e di topino aduho 

 dopo somministrazione di estratto acquoso di 

 ghiandola pineale. Arch. "E. Maragliano" pat. 

 e clin., 9, 433. 



