Mcgraw hill ryerson biology 11 textbook pdf follicles in their earliest stage. Follicle from which the ovum has escaped.
It is the remains of the ovarian follicle that has released a mature ovum during a previous ovulation. 2 cm to 5 cm in diameter. Its cells develop from the follicular cells surrounding the ovarian follicle. Progesterone is synthesized from cholesterol by both the large and small luteal cells upon luteal maturation. Cholesterol is released and stored within the cell as cholesterol ester.
LDL is recycled for further cholesterol transport. Small luteal cells have LH receptors that regulate PKA activity within the cell. Pregnenolone is then converted to progesterone that is secreted out of the cell and into the blood stream. During the bovine estrous cycle, plasma levels of progesterone increase in parallel to the levels of P450scc and its electron donor adrenodoxin, indicating that progesterone secretion is a result of enhanced expression of P450scc in the corpus luteum. Apparently to cope with the radicals produced by this system and by enhanced mitochondrial metabolism, the levels of antioxidant enzymes catalase and superoxide dismutase also increase in parallel with the enhanced steroidogenesis in the corpus luteum. The corpus luteum is essential for establishing and maintaining pregnancy in females.
In 1968, a report indicated that beta-carotene was synthesized in laboratory conditions in slices of corpus luteum from cows. However, attempts have been made to replicate these findings, but have not succeeded. The idea is not presently accepted by the scientific community. Rather, the corpus luteum concentrates carotenoids from the diet of the mammal. Similar structures and functions of the corpus luteum exist in some reptiles.
Dairy cattle also follow a similar cycle. Molecular control of luteal secretion of progesterone”. Antioxidant capacity is correlated with steroidogenic status of the corpus luteum during the bovine estrous cycle”. Electron leakage from the adrenal cortex mitochondrial P450scc and P450c11 systems: NADPH and steroid dependence”. Diagram of the pathways of human steroidogenesis”. Carotenoid metabolism as a preparation for function. Pure and Applied Chemistry, Vol.