{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Human chorionic gonadotropin (hCG) plays multiple, pivotal roles in reproductive physiology by acting as both a luteotropic and ovulatory signal as well as a diagnostic and research tool. In the ovary, hCG stimulates corpus luteum steroidogenesis in a stage‐dependent manner by enhancing the expression of key regulatory proteins such as the steroidogenic acute regulatory protein (StAR), thereby promoting progesterone and estradiol synthesis; this response is most robust during mid‐ and late-luteal phases and can be restored in early luteal tissue once endogenous gonadotropin support is withdrawn"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": " hCG also serves as an effective pharmacologic trigger for final oocyte maturation in assisted reproductive protocols by eliciting an endogenous surge of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), resulting in timely ovulation and improved oocyte quality."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": " \n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In males, hCG mimics LH action on Leydig cells, thereby stimulating testosterone synthesis; however, its effectiveness may be modulated by local endocrine factors such as estrogens and prolactin, as well as by alterations in receptor binding characteristics that affect downstream signaling efficiency."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "5", "end_ref": "8"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In various animal models, supplemental or targeted administration of hCG (often in combination with other gonadotropins) has been shown to enhance ovulatory responses and luteal function. For instance, in gilts and goats, the addition of hCG to stimulation regimens increased circulating progesterone levels and improved the synchrony of ovulation, thereby optimizing fertility outcomes."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "9", "end_ref": "12"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Beyond its direct endocrine actions, hCG is utilized in clinical settings as a marker for early pregnancy and, when measured in conjunction with histopathologic evaluation, aids in the diagnosis of ectopic gestations."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "13"}]}, {"type": "t", "text": " Moreover, studies investigating ovarian enzyme activities have demonstrated that hCG exposure can modulate key steroidogenic enzymes through genomic mechanisms, an effect that is sensitive to inhibitors of protein synthesis."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "14"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Finally, hCG-induced luteinization is also accompanied by regulatory events at the post-transcriptional level. For example, during the early phase of the follicular-to-luteal transition, specific microRNAs (e.g., rno-miR-376a) act to fine-tune the expression of chaperone proteins such as GRP78, thereby affecting luteal development and function."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "15"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Collectively, these findings underscore the multifaceted roles of hCG in orchestrating ovulation, supporting luteal function, modulating testicular steroidogenesis, and serving as a clinical tool for reproductive monitoring, thereby establishing its critical importance in both human and animal reproductive endocrinology."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}, {"type": "fg_f", "ref": "3"}, {"type": "fg_f", "ref": "9"}, {"type": "fg_f", "ref": "4"}, {"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": "\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Paulina Kohen, Olga Castro, Alberto Palomino, et al. 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