Reproductive System Structure

Structure of the reproductive system in the human body.

A. Male genital organs. Sperm cells are produced in the testes, located in the scrotum, and then transferred to the epididymis, coiled tubules, where they are stored and undergo final maturation. During ejaculation, sperm cells are forced up into the vasa deferentia, which elongate up from the epididymis, to behind the bladder. The ends of the vasa deferentia are called the ejaculatory ducts. The seminal vesicles, located behind the bladder, produce seminal fluid which contains mucus, amino acids, fructose as the energy source for the sperm, and prostaglandins. The seminal vesicles empty into the ejaculatory ducts, which empty into the urethra. The prostate gland secretes alkaline secretions directly into the urethra, to buffer any residual urine. The bulbourethral glands (Cowper’s glands) are a small pair of glands along the urethra, below the prostate, which secrete lubricant fluid just before emission of the semen. The urethra passes through the penis. In humans, the penis contains three cylinders of spongy, erectile tissue.

B. Female genital organs. The uterus, a hollow, pear-shaped organ within which embryonic development takes place. The uterus is divided into two parts: the cervix, the lower part that opens into the vagina, and the corpus, the main body of the uterus. The vagina is a canal that joins the cervix to the outside of the body. Ovaries are oval-shaped glands located on either side of the uterus, which produce ova and hormones. The ovarian follicle is the functional unit of the ovary, in which folliculogenesis, the process of oocyte maturation, takes place. Following ovulation, the release of a mature ovum, the remaining follicle cells form the corpus luteum. The oviducts (fallopian tubes) are narrow tubes that attach to the upper part of the uterus, through which the ova travel from the ovaries to the uterus. Fertilization of an ovum by a sperm, normally occurs in the fallopian tubes. From there, the embryo moves to the uterus, where it is implanted into the lining of the uterine wall, the endometrium.