Because Wolbachia are absent from mature sperm and appear to be excluded during the individualization process, the modification must occur before the conclusion of spermatogenesis.

It was only found in one tissue type, the testes, and only in the tail of mature sperm.

They have just one set of chromosomes, like mature sperm or mature eggs.

In a pilot study of 16 men from 1997, testis FNA was used to "map" the organ for mature sperm.

In males 20-39 years old, 90% of the seminiferous tubules contain mature sperm.

In males 80 years old and older, 10% of the seminiferous tubules contain mature sperm.

In males 40-69 years old, 50% of the seminiferous tubules contain mature sperm.

Wolbachia species are present in mature eggs, but not mature sperm.

Males are usually six to eight weeks old before mature sperm are produced.