<P> The follicle proper has met the end of its lifespan . Without the oocyte , the follicle folds inward on itself , transforming into the corpus luteum ( pl . corpora lutea ) , a steroidogenic cluster of cells that produces estrogen and progesterone . These hormones induce the endometrial glands to begin production of the proliferative endometrium and later into secretory endometrium , the site of embryonic growth if implantation occurs . The action of progesterone increases basal body temperature by one - quarter to one - half degree Celsius ( one - half to one degree Fahrenheit ) . The corpus luteum continues this paracrine action for the remainder of the menstrual cycle , maintaining the endometrium , before disintegrating into scar tissue during menses . </P>
immediately after expulsion of the ovum the ruptured follicle is now referred to as
the corpus luteum