Definition - What does Immature Sperm mean?
An immature sperm is a precursor cell in the pathway of sperm cell production that lacks the characteristic features and functions of a mature sperm. An immature sperm cannot swim its way through the fallopian tube to reach the egg and does not have the ability to break down the wall of the egg to fertilize it. For this reason, people with a relatively high proportion of immature sperm have low fertility.
An immature sperm is also called a spermatid or sperm precursor cell.
FertilitySmarts explains Immature Sperm
By a series of cell divisions and maturation referred to as spermatogenesis, spermatogonia in the testes produce spermatids. These spermatids are immature sperm cells and require another process called spermiogenesis to acquire the final form that can effectively fertilize an egg.
The process by which spermatids transform to mature sperm cells involves 4 steps. Spermatids pass through the golgi phase, cap phase, acrosomal phase and finally the maturation phase, during which the spermatids lose their spherical shape and acquire the characteristic 'tadpole' shape, with an elongated head, connecting piece and a tail.
Immature sperm are not motile, which makes it difficult for them to make the journey from the vagina to the fallopian tube. Even if they do, the lack of a formed head with digestive enzymes at the end limits their ability to penetrate the wall of the egg to fertilize it.
This pathway of maturation of sperm can be interrupted by various mechanisms, leading to release of immature sperm to the semen. Possible causes include genetic mutations, infection, injury to the testis, prolonged exposure to heat/cold, toxins or imbalance of hormones. The resulting reduced overall number of mature sperm decreases the ability of a person to fertilize an egg, causing male infertility.