23.
After ovulation the ovary enters the luteal phase (days 16–28) and produces progesterone. Progesterone stimulates secretion from the uterine glands (called the secretory phase of the uterus).
24.
In the absence of an implanting embryo the corpus luteum dies, progesterone production ceases, and the uterine endometrium is sloughed (called the menstrual phase, or period, of the uterus—this corresponds to days 1 to 5 of the follicular phase of the ovary).
25.
The cervix is the lower portion of the uterus. Cervical mucus is hormonally regulated so that at midcycle in response to estrogen, cervical mucus promotes entry of sperm into the uterus from the vagina. During the luteal phase in response to progesterone, cervical mucus becomes thick and poses a barrier to entry of sperm and microbes into the uterus.
We wish to thank Dr. Lisa Mehlmann for her advice on this chapter, and especially for help in drawing
Figures 44.31 44.32
Achar S, et al. Cardiac and metabolic effects of anabolic-androgenic steroid abuse on lipids, blood pressure, left ventricular dimensions, and rhythm. Am J Cardiol. 2010;106:893-901.
Coticchio G, et al. Oocyte maturation: gamete-somatic cells interactions, meiotic resumption, cytoskeletal dynamics and cytoplasmic reorganization. Hum Reprod Update. 2015;21:427-454.
Defeudis G, et al. Erectile dysfunction and its management in patients with diabetes mellitus. Rev Endocr Metab Disord. 2015; 16:213-231.
Franca LR, et al. The Sertoli cell: one hundred fifty years of beauty and plasticity. Andrology. 2016;4:189-212.
Kosaka T, et al. Is DHT production by 5alpha-reductase friend or foe in prostate cancer? Front Oncol. 2014;4:article 247.
26.
Fertilization is a complex series of events that occur in the oviduct and lead to penetration of the oocyte by sperm.
27.
Early embryogenesis (up to day 6 after fertilization) occurs in the oviduct and gives rise to a blastocyst that hatches from the zona pellucida.
28.
The placenta develops from the outer extraembryonic trophoblast. The endocrine function of the placenta includes production of hCG, progesterone, estrogens, and placental lactogen. Estrogen production requires placental cells (syncytiotrophoblasts) as well as the fetal adrenal and liver—collectively called the fetoplacental unit.
29.
Pregnancy and the hormones of pregnancy induce major changes in maternal physiology, including an increase in insulin resistance, an increase in the use of free fatty acids by the mother, and development of the mammary glands. Mammary gland development (but not lactation) is promoted by estrogen, progesterone, and placental lactogen but also by maternal pituitary prolactin, whose secretion is stimulated by placental estrogens.
30.
Oxytocin is a pituitary hormone that promotes contraction of certain smooth muscles, including myometrial contractions during labor and myoepithelial contractions in the breasts that lead to let-down of milk in response to suckling.
31.
Menopause results from exhaustion of the ovarian reserve and is characterized by low ovarian hormone and elevated gonadotropin levels.