676 TEXTBOOK OF ZOOLOGY 



characteristics. The earlier concept that the male sex produces 

 "male" hormones exclusively and the female produces only "fe- 

 male" hormones is no longer held. For example, extracts have been 

 prepared from the urine of women as well as from men which on 

 injection into capons caused growth of the comb which ordinarily 

 fails to develop as it would in the cock. The sex hormone sub- 

 stances affecting the male are spoken of as androgenic and those 

 affecting the female as estrogenic. The important sex hormones are 

 androsterone, testosterone, tJieelin, and progesterone (progestin). The 

 first two are male hormones, and the others are female. 



Androsterone is found in male urine and can be crystallized from 

 it. It has a stimulating effect on development of secondary sex char- 

 acteristics and a definite regenerative effect on accessory organs 

 (seminal vesicles, prostate glands, and penis) of castrated male ani- 

 mals. Testosterone is produced in the interstitial tissue of the testis 

 but is absent from the urine. This hormone is several times as 

 effective as androsterone in bringing about regeneration of acces- 

 sory sex organs in castrated males. Recently androgenic hormones, 

 which are potent enough to affect the growth of comb in the capon, 

 have been found in the urine and ovaries of female animals. 



Theelin (oestrin, estrogen, folliculin, menoform, progynon) has 

 been isolated from liquor folliculi, pregnancy urine, the placenta, 

 and amniotic fluid. This substance causes (1) increased growth of 

 the accessory female organs (uterus, oviducts, etc.), including changes 

 in the glands of their linings and in vascularization; (2) contraction 

 of the smooth muscle of the uterus; (3) initial growth of mammary 

 glands and nipples; and (4) sudden lowering of theelin concentra- 

 tion in blood (suggested as cause for bleeding during menses). The 

 secretion of theelin is influenced by the gonadotropic principle of 

 the anterior pituitarj^ 



Progesterone (lutein hormone, corporin, luteosterone progestin) is 

 a female hormone produced by the corpus luteum, the yellow body 

 of material which forms in the ruptured Graafian follicle after the 

 escape of the ovum. It produces the following effects: (1) sensitiza- 

 tion of the lining of the uterus so that implantation or attachment 

 of the zygote may take place in case of fertilization; (2) develop- 

 ment of placenta; (3) arrest of rhythmic contractions of the smooth 

 muscle of the uterus; (4) inhibition of ovum production and uterine 

 bleeding. 



