The spermatid is the haploid male gametid
A gametid is a kind of germ cell that results from the meiosis of a gametocyte. Male gametids are spermatids, while female gametids are ootids. The development of a gametids is called gametidogenesis....

 that results from division of secondary spermatocyte
A spermatocyte is a male gametocyte, derived from a spermatogonium, which is in the developmental stage of spermatogenesis during which meiosis occurs. It is located in the seminiferous tubules of the testis.-Spermatogenesis:...

s. As a result of meiosis
Meiosis is a special type of cell division necessary for sexual reproduction. The cells produced by meiosis are gametes or spores. The animals' gametes are called sperm and egg cells....

, each spermatid contains only half of the genetic material present in the original primary spermatocyte.

Spermatids are connected together by cytoplasmic material and have superfluous cytoplasmic material around their nuclei.

When formed, early round spermatids must undergo further maturational events in order to develop into spermatozoa, a process termed spermiogenesis
Spermiogenesis is the final stage of spermatogenesis, which sees the maturation of spermatids into mature, motile spermatozoa. The spermatid is more or less circular cell containing a nucleus Golgi apparatus, centriole and mitochondria...

 (also termed spermeteliosis).

The spermatids begin to grow a living thread, develop a thickened mid-piece where the mitochondria become localised, and form an acrosome
The acrosome is an organelle that develops over the anterior half of the head in the spermatozoa of many animals. It is a cap-like structure derived from the Golgi apparatus. Acrosome formation is completed during testicular maturation. In Eutherian mammals the acrosome contains digestive enzymes...

. Spermatid DNA also undergoes packaging, becoming highly condensed. The DNA is packaged firstly with specific nuclear basic proteins, which are subsequently replaced with protamines during spermatid elongation. The resultant tightly packed chromatin
Chromatin is the combination of DNA and proteins that make up the contents of the nucleus of a cell. The primary functions of chromatin are; to package DNA into a smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis and prevent DNA damage, and to control gene...

is transcriptionally inactive.

External links

- "Male Reproductive System: testis, early spermatids" - "Male Reproductive System: testis, late spermatids"
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