THE MAMMALIAN TESTIS 



A. Albert, Ph.D., M.D. 



PROFESSOR OF PHYSIOLOGY, MAYO FOUNDATION, AND HEAD OF 

 THE ENDOCRINOLOGY LABORATORY, MAYO CLINIC, 



ROCHESTER, MINNESOTA 



I. Introduction 305 



II. Postnatal Development of the 



Testis 307 



III. Descent of the Testis 309 



IV. Breeding Patterns 315 



V. Architecture of the Testis 317 



VI. The Circulatory System of the 



Testis 318 



VII. The Nervous System and the 



Testis 321 



VIII. The Excretory Duct System 323 



IX. The Seminiferous Epithelium.... 323 



X. The Interstitial Tissue 329 



XI. Hormones of the Testis 332 



XII. Effects of the Pituitary on the 



Testis 335 



XIII. Effects OF Steroids ON THE Testis. 337 



A. Androgens 338 



B. Estrogens 343 



C. Adrenal Steriods 344 



I). Miscellaneous Steroids and Mix- 

 tures of Steroids 345 



XIV\ Effects of Altered Endocrine 



States on the Testis 346 



XV. Nonneoplastic Disorders of the 



Testis 348 



XVI. Tumors of the Testis 349 



XVII. Conclusion 351 



XVIII. References 353 



I. Introduction 



The function of the testis is concerned 

 with the preservation of the species. It ac- 

 complishes this by producing sperm and 

 hormones. The tubular apparatus is re- 

 sponsible for the manufacture of sperm, and 

 the interstitial tissue gives rise to the hor- 

 mones. These two compartments are inti- 

 mately associated with one another embryo- 

 logically, anatomically, and functionally. 

 Furthermore, they are controlled by sepa- 

 rate gonadotrophic hormones of the anterior 

 pituitary. In turn, the secretion and me- 



305 



tabolism of the pituitary gonadotrophins 

 are controlled by the tubules and the Leydig 

 cells. Knowledge of this reciprocal control 

 of pituitary-testis activity was well estab- 

 lished by 1940; in general, this reciprocity 

 is the basic frame of reference for the in- 

 terpretation of all aspects of testicular func- 

 tion. JMore intimate relationships are quite 

 complex and, as will be seen, not completely 

 understood. 



It would be gratifying to interpret all as- 

 pects of the testis within this fundamental 

 frame of reference. This is not possible at 

 present because the literature is too con- 

 flicting and no one has a sufficiently broad 

 experience with testicular endocrinology to 

 sift all of this literature competently. The 

 extreme scatter of literature on the testis 

 furnishes ample evidence for the disconti- 

 nuity and heterogeneity of effort. Perhaps 

 the main service of this chapter is the com- 

 pilation in broad categories of the hetero- 

 geneous literature of the past 20 years, so 

 that the student may have a handy, albeit 

 incomplete, guide to the subject and to 

 several of the major problems. A preview of 

 the material to be discussed follows. 



This chapter pertains to the testis in post- 

 natal life. Acquaintance with the principal 

 facts of the embryology of the testis and 

 with recent developments in fetal endo- 

 crinology of the testis is presumed. Only a 

 short description of the postnatal develop- 

 ment of the testis is given because en- 

 cyclopedic coverage is to be expected in 

 other treatises, and because the acquisition 

 of further details of the postnatal develop- 

 ment of the testis in various species belongs 



