Diagrammatic representation of the steroid biosynthetic pathways. Ovarian sex steroid pathways are in red. P450c, cytochrome P450; LH, luteinizing hormone; DH, hydroxylase; DHEA, dehydroepiandrosterone; DOC, desoxycorticosterone; cmpd B, corticosterone; cmpd S, II-desoxycortisol

Late secretory phase endometrium. Note the tortuous, saw-toothed appearance of the endometrial glands with secretions in the lumens. The stroma is edematous and necrotic during this stage leading to sloughing of the endometrium at the time of menstruation

Schematic representation of the sequence of events occurring in the ovary during a complete follicular cycle.

Schematic representation of the sequence of events occurring in the ovary during a complete follicular cycle

Hormone levels during a normal menstrual cycle

Hypophyseal-pituitary portal circulatory system