During fertilisation the haploid nucleus of a sperm cell and the haploid nucleus of an egg cell fuse together to form a diploid zygote.

The nucleus of a germline stem cell undergoes two divisions, firstly separating homologous chromosomes and secondly separating chromatids. Haploid gametes contain 23 single chromosomes.

Gametes are haploid cells, and each cell carries only one copy of each chromosome. These reproductive cells are produced through a type of cell division called meiosis. During meiosis, a diploid ...