How it works
This spermatogenesis diagram labeled with thirteen parts follows one stem cell through mitosis and meiosis to four sperm. A second view shows the wall of a seminiferous tubule, where the same cells lie between Sertoli cells.
Read the full guide
Read it as a spermatogenesis flow chart
Start at the top. A spermatogonium (2n) divides by mitosis; one daughter cell becomes a primary spermatocyte. Meiosis I makes two secondary spermatocytes (n). Meiosis II makes four spermatids. Spermiogenesis reshapes each spermatid into a sperm, with no further division.
Then find the cells in the tubule wall
The second view keeps the same order and tints. The youngest cells lie against the basement membrane and the sperm tails hang into the lumen. Sertoli cells span the whole wall; interstitial cells lie outside the tubule.
- The cell count doubles at each meiotic division: one, two, four. The chromosome number halves once, at meiosis I.
- Spermatogenesis is the whole process. Spermiogenesis is only its last step, from spermatid to sperm.
Questions and answers
What are the stages of spermatogenesis in order?
Spermatogonium, primary spermatocyte, secondary spermatocyte, spermatid, sperm. Mitosis comes first, then meiosis I and meiosis II, then spermiogenesis.
How many sperm come from one primary spermatocyte?
Four. Meiosis I divides the primary spermatocyte into two secondary spermatocytes, and meiosis II divides each of those into two spermatids. Each spermatid becomes one sperm.
Which cells in spermatogenesis are diploid and which are haploid?
Spermatogonia and primary spermatocytes are diploid, with 46 chromosomes. Secondary spermatocytes, spermatids and sperm are haploid, with 23.
What do Sertoli cells do?
Sertoli cells are tall supporting cells in the wall of the seminiferous tubule. They reach from the basement membrane to the lumen and surround and support the developing cells.