MAMMALIAN TESTIS 



331 



■#\ 



2!^ 22 23 24 



Undifferentioted cells 



P'' 



25 





26 27 



Differentioting cells 



28 



29 



/^J) 



// 



ti^^ 



V / ^0 ^' . 



Young Leydig cells 



/ 



32 



V-^ 



33 



Mature Leydig ceils 



36 



(f^ 



Leydig cells from oid animoi 



^:\ 



38 



Fig. 5.13. Life history of Leydig cells of the bull testis. 21 to 2S, calf 1 month old. 2.'^, 

 calf \Vz months old; note threadlike processes extending from angulation of mesenchymal 

 cell. 25 to 21, cells of interstitium; 25 is a fibroblast, and 26 and 21 are pre-Leydig cells. 

 2S, bull 4 months old. ;^9 and SO, bull 2 years old, with young Leydig cells. SI and S2, bull 

 28 months old; note vacuoles. SS to 35, mature Leydig cells in a 5-year-old bull. SQ to S8, bull 

 15 years old. (From C. W. Hooker, Am. J. Anat", 74, 1, 1944.) 



- ^ - ^ — ( O U #:v;(^:;-yv:;(^ 



Fig. 5.14. Life history of the Leydig cell of the bull. (From C. \V. Hooker, Recent Progr. 

 Hormone Res., 3, 173, 1948.) 



