STEROIDS AND GROWTH 399 



caused a resumption of growth. These studies were not only the first 

 experimental demonstration of the efi^ects of androgen deprivation but 

 among the first studies of the function of the endocrine gland. 



Such experiments were the first of many which demonstrated that 

 the growth of the comb is under the control of the male hormone. 

 Following castration and involution of the cock's comb, the comb main- 

 tains a constant size over a long period, and the administration of tes- 

 tosterone or other androgens restores the comb to its normal size. The 

 growth of the comb in the capon or the chick is proportional to the 

 dose of androgen; it serves, therefore, as a means of assay for andro- 

 genic potency (cf. Dorfman, 1950; Dorfman and Shipley, 1956). The 

 androgens may be applied locally to the comb, injected intra.muscu- 

 larly, or administered orally. 



Male White Leghorns are approximately 15 times as sensitive as 

 the Rhode Island Reds and 20 times as sensitive as the Rarred Rock to 

 the local application of testosterone propionate ( Dorfman, 1948 ) . Simi- 

 lar diflFerences in sensitivity are present in female chicks of the same 

 breeds. Methyltestosterone, a derivative of testosterone which is well 

 absorbed after oral administration, also produces a marked effect on 

 comb growth (Dorfman, 1950). In both of the examples cited, there 

 is a very close relationship between the dose of the hormone and the 

 comb response. 



Seminal vesicles. Within two to five days after castration, the 

 seminal vesicles of an adult rat begin to show involution and loss of 

 weight, the changes becoming maximal in about two weeks. During the 

 period of involution, there is a loss of secretion granules, a severe re- 

 duction of the Golgi apparatus, and a progressive involution of the 

 secretory epithelium (Moore et al., 1930). Similarly, castration of the 

 immature male rat arrests the further development of the seminal 

 vesicles. 



Testosterone and other androgens can reverse the changes induced 

 by castration in the adult rat and can stimulate and seminal vesicles in 

 an animal castrated before puberty or in an immature, intact rat ( Car- 

 ter ef al, 1947; Dorfman and Shipley, 1956; Dorfman, 1950). An ex- 

 cellent dose-response relationship exists, and Mathieson and Hays 

 (1945) developed this as an assay method for androgens. The typical 

 stimulating effect of testosterone on seminal-vesicle weight is illustrated 

 in Figure 6. The functioning of the seminal vesicle is affected quite 

 rapidly, and within ten hours after the administration of testosterone, 

 increases in Qo., intracellular water, and fructose can be demon- 

 strated (Rudolph and Samuels, 1949). 



It will be noted also in Figure 6 that estrogens, such as estrone, 

 produce an increase in the seminal-vesicle weight above the castrate 

 level. With estrogen therapy the seminal vesicle will approximately 



