MAMMALIAN TESTIS 311 



the term should be restricted to designate nal cavity. Early work by Moore (reviewed 

 an abnormal testicular position in those spe- by Moore, 1951) showed that the testes 

 cies whose testes normally are scrotal. In of rats, rabbits, and guinea pigs become 

 such species, cryptorchism of sufficient du- atrophic within a few weeks when placed 

 ration results in an irreversible loss of sper- in the abdominal cavity. Moore wrapped the 

 matogenic function and in a variable failure testes of the ram with wool batting, with 

 of hormonal function. the result that the ram was sterilized by its 

 In most animals the testicular tempera- own body heat. The application of water 

 ture afforded by the scrotum is 1 to 8°C. 5°C. above body temperature to the scrotum 

 lower than the body temperature. In man of guinea pigs causes temporary sterility, 

 the testicular temperature is 1.5 to 2.5°C. The deleterious effects of increased tempera- 

 lower than the temperature of the abdomi- ture also are observed in man. Fever, dia- 



4- Testis at 3 months. More coiling of tubules is present; diameter is 50 to 60 /i. Cyto- 

 plasm of Sertoli cells is developed and still fills the lumen. A few spermatogonia are present. 

 Intertubular spaces are narrow and interstitial cells have regressed. 



5. Testis at 3 months and 25 daj's. Considerable increase in length, with coiling of tubules, 

 has occurred. Tubides are small (50 to 60 n), compact, and filled with the Sertoli nuclei. 

 There are occasional spermatogonia. The peritubular arrangement of dark-stained nuclei 

 of intertubular tissue is clearty seen. 



6. Testis at 4 months and 24 days. Tubules are small and closely packed. The size has not 

 changed (50 to 60 m). Tlie Sertoli nuclei fill the lumen, only occasional spermatogonia be- 

 ing seen. 



7. Testis at 1 year, 3 months, 24 days. Tubules are still small (40 to 50 fi). Spermatogonia 

 are now increased in number and size. Nuclei of vmdifferentiated cells fill the lumen. Only 

 dark-stained nuclei in rows around tubules are seen in narrow peritubular spaces. 



S. Testis at 1 year, 8 months, 7 days. Tubules are still small (50 yu). The Sertoli nuclei 

 continue to crowd the lumen. Intertubular tissue is undifferentiated. 



9. Testis at 2 years, 7 months, 6 days. Note that during an entire year no appreciable ad- 

 vance in development has occurred except in multiplication of the Sertoli nuclei and a 

 slight increase in tubular diameter (60 to 70 /n). Some of the interstitial cells are now lighter 

 staining. 



10. Testis at 2 years, 9 months, 21 days. Tubules are now definitely larger (90 /i). Sertoli 

 cells have moved to the periphery of the tubule. Spermatogonia are nvmiorous and rounded. 

 Rounded Lej'dig cells are now freciuently seen. 



11. Right testicular biopsy at 2 years, 4 months, 11 days. Tubules are long, convoluted, 

 and closely packed, measuring 50 to 70 m in diameter. Sertoli cells are poorly differentiated, 

 but the cytoplasm is increasing and the nuclei have partially moved basally. Interstitial 

 cells are small and sparse. 



12. Right testicular biopsy at 2 years, 9 months, 16 days. The changes are slight. Tubules 

 are somewhat larger (70 m) and the Sertoli nuclei are more basal. No differentiation of the 

 Leydig cells is seen. 



IS. Right testicular biopsy at 3 years, 1 month, 26 days. Tubules have increased slightly 

 in diameter (80 to 90 m)- The Sertoli nuclei are now definitely basal. A few cells, recog- 

 nizable as spermatocytes I by the spireme, are present. Interstitial cells are still not clearly 

 recognizable. 



14. Left testis at 3 years, 2 months, 14 days. Tubules measure 100 to 120 /a. Many sper- 

 matocytes are now present. Canalization is seen in a few tubules. A few epithelioid Leydig 

 cells are present singly or in pairs. 



15. Testicular biopsy at 2 years, 7 months, 14 days. Tubules measure 70 m. The Sertoli 

 nuclei are basal. A few desciuamating cells are present in the meshes of the Sertoli cyto- 

 plasm. Occasional Leydig cells are recognizable. 



16. Testicular biopsy at 3 years and 17 days. Tubules measure 70 to 80 m- The Sertoli 

 nuclei are basal. Vascularity has increased, and more space is present between tubules. Epi- 

 tlielioid Leydig cells are present, although not of mature size. Spermatocytes are appear- 

 ing. 



17. Left testis at 3 years, 2 months, 14 days. Tubules measure 100 to 120 fi. Formation 

 of spermatocytes I is abundant. 



18. Testicular biopsy at 3 years, 5 months, 28 days. Tubules measure 130 to 150 ti. Many 

 spermatids and some sperm cells are present. Some desquamation of immature cells is still 

 present in the tubular lumen. (From G. van Wagenen and M. E. Simpson, Anat. Rec, 118, 

 231, 1954.) 



