How are sperms made in the body?



More specifically, how does a Sperm become X or Y sperm.

In: Biology

When most cells divide, they copy themselves once then split once, so both copied cells have X *and* Y. Sperm basically come from 1 copy but 2 splits, so you get one X sperm and one Y sperm from the second split.

Not going too much into the scientificy details, mainly because I don’t remember them from high school 2 decades ago, but basically the cell division that occurs to form the reproductive cells (sperm/eggs) in humans is not the same as the cell division for none reproductive cells.

When the “normal” cells split, they create complete copies of each chromosome pair (your DNA is made of pairs of each chromosome. One comes from the father, one from the mother), so the child cells end up with a complete set of DNA.

Reproductive cells split the chromosome pairs. The child cells only receive one chromosome from each pair. In the case of the sex chromosome pair, a male has an XY pair and a female has an XX pair. So when a male creates reproductive cells (sperm), one sperm will receive the X chromosome and the other will have the Y chromosome.

Sperm cells are made in the seminiferous tubules which are located in the testes. Sperm cells are made through a process called meiosis. Our cells contain 46 chromosomes in 23 pairs of 2 identical chromosomes. Reproductive cells (sperm and eggs), however, only have 1 pair of 23. In the seminiferous tubules, specialized stem cells duplicate and divide. One of these cells will then undergo meiosis, which is the process of dividing and exchanging genes, with the end result being 4 sperm cells with unique, random set of genes comprising one set of 23 chromosomes with 2 having an single X chromosome and 2 having a single Y chromosome (normally, although errors can happen that create abnormal chromosome counts.)