The Mechanisms of Senescence 



which follow gonadectomy, and many of them are reversible 

 by gonadal hormones. (Korenchevsky et aL, 1950; McGavack, 

 1951). The peripheral effects of sex hormones in senility, such 

 as the recornification of the vagina by oestrogen (Loeb, 1944), 

 are familiar enough. The decrease of mitotic rate and degree 

 of vacuolation in the adrenal (Townsend, 1946; Blumenthal, 

 1945) and the increase of collagen and reticulum in the capsule 



MC 

 16 

 15 



14 



13 

 12 



II 

 10 

 9 ■ 

 8 - 

 7 • 

 6 ■ 

 5 ■ 

 4 • \ ><\KIRK,I949 



3 



2 ■ 

 I - 



-HAMBURGER, 1949 



HAMILTON AND HAMILTON, 1948 ROBINSON, 1948 



YEARS 40 50 60 70 80 90 



Fig. 41. — Neutral 1 7-Ketosteroids, 24-hour urinary excretion (Kirk 1949). 



and in the parenchyma (Dribben and Wolfe, 1947) which 

 occur with advancing age are partially reversible by oestrogen, 

 and more fully reversible by a combination of oestrogen, 

 androgen and progesterone (Korenchevsky, Paris and Ben- 

 jamin, 1950). In the pituitary of the senile rat, Wolfe (1943) 

 found a decrease in eosinophils, but no increase in basophils 

 vacuolation, like that which follows castration, occurred in the 

 basophils with increasing age. These changes, particularly the 

 decrease in eosinophils, are at least partially reversed by testos- 

 terone propionate (Wolfe, 1941). The senescent changes in 



173 



