The two cells hypothesis
A. The preovulatory follicle produces estradiol through a paracrin interaction between the theca and granulosa cells. Theca cells provide the granulosa cells with androstenedione in order to produce estradiol. Granulosa cells express the right enzymes that convert androstenedione to estradiol (P450 aromatase, 17β hydroxysteroid dehydrogenase1).
B. In corpus luteum, granulosa cells obtain vessels, LH receptors and enzymes for progesterone synthesis. Theca cells are the source of androstenedione that is necessary for the production of estradiol in granulosa cells. Gonadotropins, steroidogenic factor 1 (SF-1) and steroidogenic acute regulatory protein (StAR) have fundamental functions in ovarian steroidogenesis. (ATP, adenosine triphosphate; cAMP, cyclic adenosine monophosphate; FSH-R, follicle stimulating hormone receptor; LH-R, luteinizing hormone receptor; P450 arom, P450 aromatase; 17β-HSD-I, 17-β hydroxysteroid dehydrogenase-I). (with permission of Larsen et al., eds. The physiology and pathology of the female reproductive axis. En: Williams Textbook of Endocrinology. Saunders; 2003; 604.)
From: Greenspan Endocrinologia Basica y Clinica Novena Edición, 2012 McGraw Hill; Translated from the ninth English edition of: Greenspan´s Basic & Clinical Endocrinology Copyright © 2011 by The McGraw-Hill Companies, Inc.