Dictionary HealthMale Reproductive SystemImmature Sperm Immature Sperm Reviewed by Dr. Oreoluwa Ogunyemi, Urologist View our Editorial Policy Published: November 21, 2017 What Does Immature Sperm Mean? An immature sperm is a “younger” sperm cell that lacks the characteristic features and functions of mature sperm. An immature sperm is immobile, so it cannot swim 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 (acrosome reaction). For this reason, men with a relatively high proportion of immature sperm can have low fertility. An immature sperm is also called a spermatid or sperm precursor cell. Advertisement FertilitySmarts Explains Immature Sperm A healthy man is likely to produce about 300 million sperm a day. This occurs through a series of cell divisions and maturation process referred to as spermatogenesis, where spermatids develop into spermatozoa (or mature sperm). The process takes around 64 days on average. The process involves 4 distinct steps. Spermatids pass through the: golgi, cap phase, acrosomal and maturation phases. During the process, spermatids, which start out as round cells that cannot move, lose their spherical shape and elongate into the 'tadpole' shape, with a long head, midpiece, and a tail. This process of sperm maturation can be interrupted, leading to the release of immature sperm to the semen. Possible causes include: Genetic mutations Infection Injury to the testis Prolonged exposure to heat/cold Toxins Imbalance of hormones This leads to a reduction in the number of mature sperm and therefore decreases the ability of the male to fertilize an egg, causing male infertility. Advertisement Synonyms Spermatid Sperm precursor cell Share This Term> Related Terms Sperm Morphology Semen Analysis Related Reading 14 Onesies that Celebrate IVF Babies IVF Pregnancy Announcements Fertility Podcasts Relatable Words After a Miscarriage Let’s Stop Arguing About Whether or Not Stress Causes Infertility Books About Infertility Tags Male Infertility Sperm Health Male Reproductive System Difficulty Sperm Problems Trending Articles Pregnancy IVF Pregnancy Announcements Egg Retrieval From Eggs to Blastocysts: Understanding IVF Attrition Cervical Mucus Identifying Stages of Cervical Mucus Artificial Insemination (AI) Implantation Calendar: What is Happening During the Two Week Wait?