= Corpus luteum
The <corpus luteum> is a temporary endocrine structure formed from the <ovarian follicle> after <ovulation>. Its luteinized <cells> produce substantial <progesterone>, helping maintain the secretory state of the <endometrium>. Without sustained hormonal support it regresses; in early <pregnancy>, <human chorionic gonadotropin> helps preserve its steroid production.<Anatomy and Physiology 2e by J. Gordon Betts and others>[Section 27.2, ovulation, corpus luteum and ovarian-cycle hormone changes]{ref}
It illustrates that an <endocrine gland> need not be a permanently separate <organ>. A local <tissue> is reorganized into a hormone-secreting structure and later changes again. A measured <progesterone> <concentration> reflects both this production and removal from the <blood>, so it is not a direct count of luteal <cells>.
Back to article page
