(3) A sperm has half the number ofchromosomes than an ordinarybody cell. Similarly ovum also hashalf the number of chromosomes.When sperm and ovum fuse, thenumber of chromosomes becomesthe same as in other body cells. Inhuman beings males have two differenttypes of sex chromosomes intheir cells (X and Y) while femaleshave similar chromosomes (X andX). So, a female has 44 + XX chromosomesin her cells and a malehas 44 + XY chromosomes in hiscells. Since the number of chromosomesis half in ova and sperms, allova will have the same chromosomes(22+X) while sperms willhave two types of chromosomes(22+Xor22+Y).