Testes are the organs of the male reproductive system. Each testis is divided into 200 to 300 lobules, each containing one to three tightly coiled tubules, the seminiferous tubules. At puberty, spermatogenesis (sperm production takes place within the seminiferous tubules. The production and survival of sperm requires a temperature that is about 3o C lower than normal body temperature. The interstitial cells, which are located between the seminiferous tubules, are responsible for producing testosterone, the most important androgen. At puberty, pituitary secretions of follicle stimulating hormone (FSH) initiate maturation of spermatozoa. Interstitial stimulating hormone (ICSH) stimulates the interstitial cells to produce testosterone. Once sperm is produced in the seminiferous tubules, it moves to a network of ducts in the testes called the rete testis. The sperm then move through the rete testis and out the testis into a posterior organ called the epididymis. The epididymis is a tightly coiled structure that stores sperm and helps and is later propelled them toward the urethra by peristaltic contractions of its smooth muscle. This is also where the sperm matures and become fertile within 10 to 14 days. Sperm may remain in storage in the epididymis for at least a month. The epididymis connects with the ductus (vas) deferens, which is about 18 inches long, stores sperm, and conveys sperm from the epididymis toward the urethra by peristaltic contractions. The urethra conducts the sperm through the penis and into the vagina of the female.
Paired, almond-shaped ovaries are the organs of the female reproductive system. After puberty, they are the sites of oogenesis (the maturation of ova). They secrete estrogens and progesterone, which are necessary for the development of other internal organs such as Fallopian tubes, uterus, and vagina, and for the development of secondary sex characteristics. Fallopian tubes (sometimes called uterine tubes or oviducts) propel the ova to the uterus using ciliary action and peristaltic movements of the smooth muscle. If fertilization occurs, it takes place in the distal third of the Fallopian tube. Fertilization may occur at any time up to about 24 hours after ovulation. If fertilization does not occur, the ovum degenerates. A fertilized egg (zygote) will arrive at the uterus about 7 days after ovulation. The uterus has an alkaline pH of 8.5, which is more conducive to the survival of sperm. It is designed to retain a fertilized egg and to sustain and nourish it during the 266 days of pregnancy. The placenta is expelled after birth has occurred.
There are few similarities between the testes and sperm ducts and the ovaries, Fallopian tubes and uterus. They share the common purpose of producing offspring. In the female Tubes the sex cell called an oocyte had to travel from it’s place of creation (ovaries) to it’s resting location (uterus), and the male sex cell known as sperm also must migrate from the seminiferous tubules into the female uterus. Both reproductive organs are produce hormones and thus can be considered part of the endocrine system.
There are several differences between male testes and sperm ducts and the female ovaries, Fallopian tubes and uterus. The most evident of which is the fact that ovaries are located deep inside the true pelvis, while the testes are located outside of the body in the scrotum. Ovaries are located slightly more lateral on a female than testes on a male and flank the uterus on each side. Sperm must travel a very long distance to reach a female uterus, while the ova are not very far from it and for the majority of their trip they simply float downwards. This is why female sex cells are round and relatively simple in structure, as they do not need much effort to maneuver. Sperm must develop a tail and a streamline shape for active swimming. Although the male sex cells must travel a longer distance through the reproductive organs, it is actually the female reproductive organs that are more complex due to the fact that females must give birth. Another rather significant difference is that sperm can survive for up to a month and can be produced continuously, while the ova will degenerate after 24 hours if not fertilized and can only be produced about once a month.
