Cat foetus (Felis catus) inside the amnion membrane. The amnion is filled with fluid, which cushions and protects the developing foetus. Blood vessels (upper centre) connect the umbilical region of the developing kitten to the placenta (not seen) on the wall of the mother's uterus, to allow the exchange of nutrients and metabolic waste products between maternal and foetal blood. This kitten is already covered in fur. Length of gestation in cats is between 63 and 68 days.