reduces it
Chapter 27 1 Sperm remain in the epididymis until they degenerate. 3 The fimbriae sweep the oocyte into the uterine tube. 5 The testes are located in the abdomen. 6 b 8 b 10 c 12 a 14 c 16 d 18 b 20 A single gamete must combine with a gamete from an individual of the opposite sex to produce a fertilized egg, which has a complete set of chromosomes and is the first cell of a new individual. 22 The three accessory glands make the following contributions to semen: the seminal vesicle contributes about 60 percent of the semen volume, with fluid that contains large amounts of fructose to power the movement of sperm; the prostate gland contributes substances critical to sperm maturation; and the bulbourethral glands contribute a thick fluid that lubricates the ends of the urethra and the vagina and helps to clean urine residues from the urethra. 24 Testosterone production by the body would be reduced if a male were taking anabolic steroids. This is because the hypothalamus responds to rising testosterone levels by reducing its secretion of GnRH, which would in turn reduce the anterior pituitarys release of LH, finally reducing the manufacture of testosterone in the testes. 26 Meiosis in the man results in four viable haploid sperm, whereas meiosis in the woman results in a secondary oocyte and, upon completion following fertilization by a sperm, one viable haploid ovum with abundant cytoplasm and up to three polar bodies with little cytoplasm that are destined to die. 28 Endometrial tissue proliferating outside of the endometriumfor example, in the uterine tubes, on the ovaries, or within the pelvic cavitycould block the passage of sperm, ovulated oocytes, or a zygote, thus reducing fertility. 30 The internal reproductive structures form from one of two rudimentary duct systems in the embryo. Testosterone secretion stimulates growth of the male tract, the Wolffian duct. Secretions of sustentacular cells trigger a degradation of the female tract, the Müllerian duct. Without these stimuli, the Müllerian duct will develop and the Wolffian duct will degrade, resulting in a female embryo.