A&P 102 Module 3 - Reproductive System

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Animals expend a considerable amount of energy and time on reproduction. After all, reproduction ensures that the animal's genes are passed on to the next generation. The life cycle of any particular ... animal comes to an end, but its genes can be perpetuated as long as reproduction has taken place. Usually animals practice sexual reproduction, which involves sex cells (gametes). The gametes may be specialized as eggs (oocytes) or sperm (spermatocytes), and even if egg and sperm are produced by the same individual, animals usually practice cross-fertilization. When animals reproduce sexually, an offspring inherits half its genes from one parent and the other half from the other parent. Therefore, an offspring has a different combination of genes than either parent. In this way, variation is introduced and maintained. Such variation is an advantage to the species if the environment is changing, because an offspring might be better adapted to the new environment than is either parent. Animals usually produce gametes in specialized organs called gonads. The gonads are testes for the production of sperm and ovaries for the production of eggs. These gametes are produced by germ cells, cells set aside early in development for this specific purpose. The other cells in a gonad support and nourish the developing gametes or produce hormones necessary to the reproductive process. Copulation is sexual union to facilitate the reception of sperm by a female. In terrestrial animals, males typically have a penis for depositing sperm into the vagina of females. [Show More]

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