Pancreas
Γhe pancreas is a pinkish Iobulated gland lying in the l∞pof thcdugerm cells in the ovary into ripe follicles is the result of the secretion of l∙'SI I from the anterior pituitary gland.
Oestrogen causes the behaviour associated with the oestrous cycle and prepares the reproductive tract and external genitalia for mating (see Ch. 1 1). Oestrogen also exerts negative feedback on the anterior pituitary gland, preventing further secretion of FSII and further Iolliculardevclopment (Fig. 6.4).2. Progesterone - secreted by the corpus Iuteum, which develops from the remaining follicular tissue after the follicle has ovulated. The corpus Iuteum develops as a result of the production of LH from the anterior pituitary gland. Progesterone prepares the reproductive tract for pregnancy and maintains the pregnancy (sec Ch. 1 I). During pregnancy, progesterone exerts negative feedback on the hypothalamus and prevents secretion of gonadotrophin releasing hormone and so prevents further oc,strous cycles until parturition occurs. It also causes development of the mammary glands during pregnancy (Fig. 6.4).
In the later stages of pregnancy, the corpus Iuleum also secretes a hormone known as relaxin. This causes the sacroiliac and other ligaments around the birth canal to soften and relax in preparation for parturition.