Fetus Development in Cats

Cats have a relatively short gestational period that averages 63 days. The size of the litter affects the actual length of pregnancy, with larger litters causing pregnancy to last longer. Birth prior to 59 days is considered premature.

  1. Fertilization

    • The zygote (a mass of cells) is formed when the sperm and egg unite. When the cell mass reaches 16 cells, it is called the morula. The morula enters the uterus and implants itself into the wall of the uterus. At this point it is considered an embryo.

    Embryo

    • During the embryo stage, the cells begin to develop into specific organ systems and the placenta develops. The heart also develops during this stage. The embryo stage lasts about 24 days. The fetal stage follows.

    Fetus

    • At this stage the fetus is about 1/2 inch long. During the fetal stage the organs continue to form and some begin to function inside the womb. The legs begin to form in this stage as well.

    Final Weeks

    • During the final weeks of pregnancy, the organs and body systems continue to mature. The paws separate into toes. The liver and kidneys enter their final stage of growth for life outside the womb.

    Birth

    • Kittens are blind and deaf at birth and are unable to hold up their heads or control the movements of their limbs. Their eyes begin to open at the beginning of the second week and should be completely open by the 14th day. Their ears open at the beginning of the third week. Kittens should be able to walk without stumbling by the fourth week.