The Beginning of Life Life begins at fertilization. Fertilization refers to the meeting of the female sex cell and the male sex cell. These sex cells are developed in the reproductive organs called gonads. The male sex cells called spermatozoa (singular: spermatozoon) are produced in the male gonads called testes. On the other hand, the female sex cells called ova are produced in the female gonads known as ovaries. The fertilized egg cell known as zygote contains all the hereditary potentials from the parents. This zygote goes to the uterus and continues to grow during the gestation period of about 280 days or 36 weeks or 9 calendar months. Each parent contributes one sex chromosome to the offspring. A male parent may pass either an X or a Y chromosome while a female always gives the X chromosome. When an X chromosome comes from the father and meets the X chromosome from the mother, the resulting combination is XX which indicates a female offspring. However, when the father produces a Y chromosome which pairs with the X chromosome from the the mother, the resulting combination is XY, signifying a male offspring.

Fertilization

refers to the meeting of the female sex cell and the male sex cell

gonads

These sex cells are developed in the reproductive organs called

spermatozoa (singular: spermatozoon)

The male sex cells ————— are produced in the male gonads called testes.

ova - ovaries

the female sex cells called —- are produced in the female gonads known as ———