The Molecular Biology Notebook OnlineYou are here: The Cell > Examples of cells > Sperm Cells
Spermatozoid or sperm cell
A sperm cell is one of the most specialised cells in the animal body.
They arise by repeated mitosis
followed by meiosis to produce haploid immature
sperm cells, each with a different genotype (if the process was meiosis
followed by mitosis all the cells would have the same genotype). This is
spermatogenesis. The sperm mature in the epidydimis, but they do not become
fully mature until they reach the female oviduct.
They have three separate regions.
The Head.
This has two important features. The acrosome contains lytic enzymes
which are released when the sperm reaches an ovum. These enzymes digest
the outer membrane of the egg, allowing penetration of the sperm. The head
also contains a single set of chromosomes derived
from the male. This will include either an 'X' or 'Y' chromosome, because
of the way the XY separate during meiosis.
The Middle Section.
This part, immediately behind the head, contains numerous mitochondria.
These respire sugars in the semen to generate ATP in order to provide the
energy for movement of the tail.
The Tail.
This contains microfilaments running the length of the tail (arranged in the usual 9 + 2 system seen in Eukaryotic organisms). Rhythmic contraction of the filaments causes the tail to wave and move against the fluid environment, providing forward motion.
