Reproductive Physiology

The only form of estrogen that is exclusively present in pregnant women is estetrol (E4).

The urethra travels through the corpus spongiosum, one of three cavernous bodies in the human penis. The other two cavernous bodies are a set of sponge-like erectile tissues called the corpus cavernosum. The vas deferens and epididymis are both part of the storage and transportation of semen. The vas deferens joins with the urethra in the penis to facilitate ejaculation.

While research is still being conducted to determine the cause of nausea and vomiting of pregnancy, it generally correlates with the surge in human chorionic gonadotropin (hCH) that occurs in the first trimester. Estrogen may be another contributing hormone. Aldosterone, DHEA, and corticotropin-releasing hormone (CRH) have no apparent involvement.

During a normal pregnancy, the volume of blood plasma increases by 50%. The erythrocyte count also increases, by as much as 30%. This may cause the hematocrit to appear lower than normal, due to dilution by the relatively larger increase in plasma.

The stability of sperm cell chromatin is dependent on zinc. Zinc deficiency can cause sperm to be fragile, which in turn lowers sperm count and decreases male fertility.

Male ejaculate can contain any where from 40 million to 1 billion sperm, though the average ejaculate contains between 100 and 400 million.

In polycystic ovarian syndrome (PCOS), luteinizing hormone (LH) levels are elevated, while follicle-stimulating hormone (FSH) levels are often low. Because FSH aromatizes androgens to estrogen, low FSH will cause androgens to increase. Low levels of FSH and high androgens keep the follicle from maturing & prevent ovulation. Hypogonadism is significantly more rare, and while extreme stress and poor nutrition may inhibit ovulation, in the United States PCOS is the leading cause of anovulation (failure to release an ovule from the ovary).

In a menstruating woman, follicle-stimulating hormone stimulates the maturation of follicles in the ovary. Rupture of the mature follicle and formation of the corpus luteum are both stimulated by lutenizing hormone (LH). The uterus itself does not contain follicles.

In a healthy adult male, follicle stimulating hormone stimulates the Sertoli cells of the testes to produce androgen-binding protein, it stimulates primary spermatocytes to undergo meiosis, and triggers the initiation of spermatogenesis.

The Sertoli cells of the testes are responsible for the secretion of many substances, including anti-Müllerian hormone, androgen binding protein, glial cell line-derived neurotrophic factor, and estradiol.