a manual of zoology 60 manual of zoology sect before the changes begin which lead to the formation of the multicellular metazoan another cell the male cell or sperm has to unite with the ovum or female cell before this takes place the ovum throws off portions of its substance fig 26pel in the form of two little rounded bodies the polar bodies this preliminary process is known as the maturation of the ovum the male cell or sperm is a relatively small cell usually motile which penetrates into fig 25ovum of a sea urchin showing the radially striated cell membrane the prot rdhdh1.jpg from extracción manual View Photo