Perivitelline space - the space between the yolk and the shell, filled with fluid that provides metabolic processes of the embryo and protects it from the external environment. It is formed in the process of egg development.

From peri... from Latin vitellus - egg yolk, the space between the embryo and the egg shell filled with perivitelline fluid. It appears during egg activation as a result of release of the contents of cortical bodies and substances localized in deeper layers of cytoplasm, and persists until the embryo hatches. Due to high osmotic activity, the secreted substances attract water and a perivitelline fluid is formed, pushing the egg shell away from the cytoplasmic surface. This fluid protects the egg from penetration of supernumerary spermatozoa, protects the embryo from mechanical damage and serves as a favorable environment for its development.