Animal Body Organization and Systems

The Reproductive System

The reproductive system is involved in the development and growth of offspring. Sexual reproduction results in offspring with unique sets of traits. Asexual reproduction results in offspring identical to the parent.

The reproductive system consists of structures involved in the formation of offspring. In mammals, these structures include the testes, penis, and associated glands of the male and the ovary, fallopian tubes, uterus, breasts, and associated glands of the female. The reproductive system supports the production of offspring in several ways. First, it aids in the production of hormones that influence the sexual traits of males and females. Second, it produces the egg and sperm cells required for the production of offspring. Third, it is involved in the sustenance and transportation of sperm and egg cells during reproduction. Last, the system is vital for the survival and development of offspring. There are two types of reproduction: asexual and sexual. The mechanisms utilized vary by species.

Asexual reproduction is a form of reproduction that does not involve fusion of gametes (egg and sperm cells), producing offspring that are genetically identical to the parent. It is often a quick process. Various organisms use different forms of asexual reproduction. For example, flatworms undergo a process called fragmentation in which they divide in two, then each half regenerates into a new flatworm. Each regenerated form is identical to the original. Parthenogenesis is a form of asexual reproduction in which an unfertilized egg cell becomes a new organism. It has been described in a small number of species of bees, parasitic wasps, fish, and lizards.

Sexual reproduction is a form of reproduction involving fusion of gametes, producing genetically unique offspring. It requires the fertilization of an egg cell by a sperm to generate a zygote. This zygote eventually becomes an embryo once it has undergone several rounds of cell division and development. In mammals, when the embryo has developed further, it is called a fetus. Sexual reproduction results in offspring with a mix of genetic information from the two parents.

In mammals, the reproductive system is more complex, and there are more organs involved in the production of offspring. Gametes are produced in the testes in males and ovaries in females. In males, the testes produce sperm, which are contained in a fluid called semen. Semen and additional secretions are released from accessory glands such as the seminal vesicles, prostate gland, and bulbourethral gland. The sperm travel through the vas deferens before being released through the penis, which is external to the body.
The male mammal reproductive system contains a variety of organs and accessory glands that are essential for reproductive function. Sperm are produced in the testis, where they travel to the epididymis to mature. Mature sperm travel through the vas deferens and are combined with seminal fluids before being ejected through the urethra.
In females, ovaries are the site of egg development. After an egg is released during ovulation, it travels down a fallopian tube or oviduct before it enters the uterus. Fertilization occurs in the fallopian tube, but the developing embryo develops in the uterus.
The female mammal reproductive system contains structures for egg production and embryo development. An egg is produced in the ovary, before it travels through the oviduct and is fertilized by a sperm. The zygote (fertilized egg) travels to the uterus where it attaches to the lining and develops into an embryo. Unfertilized eggs are released with the uterine lining as menstruation.