. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. ACTIVITIES OF THE OVARY 91 of the egg follicle, but also, after ovulation or the discharge of the egg from the egg follicle, the remaining granulosa cells, and also, some of the theca interna cells of the follicle are induced by the LH factor to form the corpus luteum (figs. 30, 49). Corpora lutea also may be induced by estrogens. This, however, appears to be an indirect stimulus aroused through estrogenic stimu- lation of the pituitary gland to s
. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. ACTIVITIES OF THE OVARY 91 of the egg follicle, but also, after ovulation or the discharge of the egg from the egg follicle, the remaining granulosa cells, and also, some of the theca interna cells of the follicle are induced by the LH factor to form the corpus luteum (figs. 30, 49). Corpora lutea also may be induced by estrogens. This, however, appears to be an indirect stimulus aroused through estrogenic stimu- lation of the pituitary gland to secrete added amounts of the LH factor (Evans and Simpson in Pincus and Thimann, '50, p. 359). A further pituitary principle, however, seems to be involved in the func- tional behavior of the corpus luteum. This principle, referred to as luteotrophin (LTH), is associated with the lactogenic-hormone complex produced by the anterior lobe of the pituitary body; it induces the morphologically developed corpus luteum to secrete progesterone. (Consult Evans and Simpson in Pincus and Thimann, '50, pp. 359, 360; Turner, '48, p. 379, for references.) The structural formula of progesterone is as follows:. ^/X/X/ 2) Effects of Progesterone. Progesterone reduces the irritability of the ac- cessory structures and stimulates the mucosa of the uterus to undergo further development. This increased developmental and functional condition of the Fig. 53. Relationship of the pituitary gonadotrophins and ovarian hormones to the de- veloping Graafian follicle and reproductive-duct change in a polyestrous female mammal. The Graafian follicle responds to the pituitary gonadotrophins. FSH and LH, with the subsequent growth and ultimate rupture of the follicle and ovulation. Ovulation termi- nates the follicular phase of the cycle. Under the influence of the LH factor the corpus luteum is established. The latter becomes functional as a result of stimulation by the luteotrophic (lactogenic) hormone. The p
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