The acrosome is an organelle that develops over the anterior (front) half of the head in the spermatozoa (sperm cells) of many animals including humans. It is a cap-like structure derived from the Golgi apparatus. In placental mammals the acrosome contains degradative enzymes (including hyaluronidase and acrosin).[1] These enzymes break down the outer membrane of the ovum,[2] called the zona pellucida, allowing the haploid nucleus in the sperm cell to join with the haploid nucleus in the ovum.

Diagram of a human spermatozoa

This shedding of the acrosome, or acrosome reaction, can be stimulated in vitro by substances a sperm cell may encounter naturally such as progesterone[3] or follicular fluid, as well as the more commonly used calcium ionophore A23187.[4] This can be done to serve as a positive control when assessing the acrosome reaction of a sperm sample by flow cytometry[5] or fluorescence microscopy. This is usually done after staining with a fluoresceinated lectin such as FITC-PNA, FITC-PSA, FITC-ConA, or fluoresceinated antibody such as FITC-CD46.[6]

In the case of globozoospermia (sperm with round heads), the Golgi apparatus is not transformed into the acrosome, causing male infertility.[7]

See alsoEdit


  1. ^ "acrosome definition - Dictionary - MSN Encarta". Archived from the original on 2009-02-14. Retrieved 2007-08-15.
  2. ^ Larson, Jennine L.; Miller, David J. (1999). "Simple histochemical stain for acrosomes on sperm from several species". Molecular Reproduction and Development. 52 (4): 445–449. doi:10.1002/(SICI)1098-2795(199904)52:4<445::AID-MRD14>3.0.CO;2-6. ISSN 1098-2795. PMID 10092125. S2CID 24542696.
  3. ^ Lishko, Polina V.; Botchkina, Inna L.; Kirichok, Yuriy (March 2011). "Progesterone activates the principal Ca 2+ channel of human sperm". Nature. 471 (7338): 387–391. Bibcode:2011Natur.471..387L. doi:10.1038/nature09767. ISSN 1476-4687. PMID 21412339. S2CID 4340309.
  4. ^ Jamil, K.; White, I. G. (December 1981). "Induction of acrosomal reaction in sperm with ionophore A23187 and calcium". Archives of Andrology. 7 (4): 283–292. doi:10.3109/01485018108999319. ISSN 0148-5016. PMID 6797354.
  5. ^ Miyazaki R, Fukuda M, Takeuchi H, Itoh S, Takada M (1990). "Flow cytometry to evaluate acrosome-reacted sperm". Arch. Androl. 25 (3): 243–51. doi:10.3109/01485019008987613. PMID 2285347.
  6. ^ Carver-Ward JA, Moran-Verbeek IM, Hollanders JM (February 1997). "Comparative flow cytometric analysis of the human sperm acrosome reaction using CD46 antibody and lectins". J. Assist. Reprod. Genet. 14 (2): 111–9. doi:10.1007/bf02765780. PMC 3454831. PMID 9048242.
  7. ^ Hermann Behre; Eberhard Nieschlag (2000). Andrology : Male Reproductive Health and Dysfunction. Berlin: Springer. p. 155. ISBN 3-540-67224-9.