In the animals that present direct development the individuals are, then from the birth, very similar to the adult state. After the fecundao, the eggs ranks for the female are presented constituted of: (1) egg yolk or vitelo, that it supplies the necessary nutrients the cellular divisions and the formation of the embryo; (2) embryo, that is restricted to the region of cicatrcula; (3) albmen or clear, that protects the embryo, cushioning the vibrations and the movements; (4) rind, of limy nature, whose membranes are permeveis, allowing the gaseous exchanges; (5) calaza, lace of albmen that insurance the egg yolk so that this can oscillate, any that is the position of the egg. With the progression of the embryonic development it is verified that the constitution of the egg if goes modifying, presenting in the end some embryonic annexes: crion, the allantois, the amniotic stock market or mnios and the vitelino bag. Throughout the embryonic development embryo goes suffering modifications. The birds try to always look a hotter place to aconchegar the egg.