The           system functions for the survival of the species.

The primary reproductive organs, also called gonads, are          , which are responsible for producing the egg and sperm cells.

Spermatogenesis differs from mitosis because the resulting cells have          the number of chromosomes as the original cell.

The final step in the development of sperm is called          .

Sperm complete their maturation process and become fertile as they move through the          .

Although only one sperm actually penetrates and fertilizes the ovum, it takes          sperm in an ejaculation to ensure that fertilization will take place.

Female sex cells, or gametes, develop in the ovaries by a form of           called oogenesis.

Functionally, the mammary glands produce milk; structurally, they are modified         .