The male and female gonads--the testes and ovaries, respectively--arise out of a common embryonic tissue called the primordial gonad. Likewise, the male penis and female clitoris arise from a common precursor called the genital tubercle. For the most part, the production of male germ cells (sperm) and female germ cells (oocytes) are driven by the same hormones, but with different patterns of secretion.
Female Reproductive Anatomy
The ovaries, paired organs in the abdomen, house the oocytes (eggs) and produce steroid hormones, primarily estrogen and progesterone. An embryonic set of tubes called the Mullerian ducts differentiate to become the Fallopian tubes and the uterus (womb). The Fallopian tubes connect directly to the uterus on each side and extend toward the ovaries. The cervix is the narrow opening at the bottom of the uterus where it meets the vagina. The remainder of the female external genitals consists of the clitoris, the vagina, and the fleshy inner and outer labia (lips) that protect the vaginal opening.
Male Reproductive Anatomy
Testes develop in the abdomen and later in embryonic development migrate to their position outside the body, in the sack of skin called the scrotum. A set of tubes called the Wolffian ducts develops into the epididymis and vas deferens, tubes leading from the testes to the penis by way of the prostate gland. The penis develops from the genital tubercle and grows under the influence of testosterone.
Puberty
For females, puberty marks the maturation of the brain system that stimulates the monthly cycle of hormonal changes. The brain secretes gonadotropin-releasing hormone (GnRH), stimulating the pituitary to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which in turn stimulate the ovarian follicles to produce estrogen and progesterone. Under this regimen of hormonal changes, the oocytes that had been held in an immature state can begin to mature.
For males, puberty sparks the secretion of more testosterone under the influence of the LH and FSH. After puberty, male hormonal secretion and the production of mature sperm occur steadily, in contrast to the monthly pattern in women.
Female Reproductive Function
Each month one ovarian follicle and its oocyte fully mature and at ovulation, the mature follicle bursts, releasing its egg. As the egg travels down the Fallopian tubes, it might be fertilized, developing into an embryo that will implant in the uterus. If the egg is not fertilized, the uterus sheds the lining it had prepared for possible implantation, resulting in menstrual bleeding. A woman is born with all the follicles and oocytes she will ever have; when that pool is exhausted, menopause ensues.
Male Reproductive Function
A man can produce new sperm throughout his life. Sperm production begins in the Sertoli cells of the testes but is finalized in the vas deferens with the production of sperm capable of swimming and fertilizing an egg. The seminal vesicles and the prostate make semen, an energy-rich fluid important for sperm function. Male erection occurs when blood fills the spongy tissues inside the penis called corpora cavernosa. At ejaculation, the sperm are propelled out of the urethral opening of the penis.
References
- Handbook of Pathophysiology; Chapter 20 "The Reproductive System"; Elizabeth Corwin; 2001.
- Endocrinology: An Integrated Approach; Chapter 6 "The Gonad"; S.S. Nussey and S.A. Whitehead; 2001.
