Nucleus of Sperm

Sperms are male reproductive cells and are motile. It has a head, connecting piece and a tail. The sperm nuclei are found in the head of the sperm, one sperm containing one nucleus. This nucleus is the aggregation of densely coiled chromatin material. It is the male genome that during fertilization fuses with the female nucleus. This male genetic material is haploid (half), containing 23 chromosomes out of a total of 46 in humans. The zygote that forms after fertilization then has diploid number of chromosomes as it gets the other 23 chromosomes from the egg. It is in the form of a dense ball containing genetic material enclosed by a nuclear membrane.

Nucleus of Egg

Egg cells are female reproductive cells which are not capable of active movement. The size of the egg cell is much larger than the sperm and has its genetic material in the nucleus. The nucleus of the egg is present in its yolk. The nucleus of the egg has haploid number of chromosomes. The nucleus of the egg contributes half of the genetic material to the zygote and transmits traits from the female to the child. The features inherited by a child from his/her mother are transferred by this genetic material in the nucleus of egg. This nucleus is called the pronucleus before it is fertilized by the pronucleus of the sperm.