What role does pituitary gonadotrophins play during follicular and ovulatory phases of menstrual cycle and also explain the shift in steroidal secretions.

Menstrual cycle is regulated by hypothalamus through the pituitary gland. At the end of menstrual phase, the pituitary FSH gradually increases resulting in follicular development within the ovaries. As the follicles mature, Estrogen secretion increases resulting in a surge in (FSHe and LH) The surge of LH15 responsible for ovulation. LH also gonadotropins induces luteinisation. This leading to the formation of corpus luteum. Corpus luteum secretes progesterone and source estrogen which help in maintaining the interine endometrium for implantation.