Acrosome - wikipedia Acrosome The acrosome is an organelle that develops over the anterior 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. Acrosome formation is fully completed 5 -- 10 years after testicular maturation. In Eutherian mammals the acrosome contains digestive enzymes ( including hyaluronidase and acrosin ). These enzymes break down the outer membrane of the ovum, called the zona pellucida, allowing the haploid nucleus in the sperm cell to join with the haploid nucleus in the ovum. This shedding of the acrosome, or acrosome reaction, can be stimulated in vitro by substances a sperm cell may encounter naturally such as progesterone or follicular fluid, as well as the more commonly used calcium ionophore A23187. This can be done to serve as a positive control when assessing the acrosome reaction of a sperm sample by flow cytometry 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. Human spermatozoön In the case of globozoospermia ( sperm with round heads ), the Golgi apparatus is not transformed into the acrosome, causing male infertility. See also Acroplaxome References Jump up ^ `` acrosome definition - Dictionary - MSN Encarta ''. Archived from the original on 2009 - 10 - 31. Retrieved 2007 - 08 - 15. Jump up ^ 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. Jump up ^ 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. Jump up ^ Hermann Behre ; Eberhard Nieschlag ( 2000 ). Andrology : Male Reproductive Health and Dysfunction. Berlin : Springer. p. 155. ISBN 3 - 540 - 67224 - 9. Structures of the cell / organelles Endomembrane system Cell membrane Nucleus Endoplasmic reticulum Golgi apparatus Parenthesome Autophagosome Vesicles Exosome Lysosome Endosome Phagosome Vacuole Acrosome Cytoplasmic granules Melanosome Microbody Glyoxysome Peroxisome Weibel -- Palade body Cytoskeleton Microfilaments Intermediate filaments Microtubules Prokaryotic cytoskeleton MTOCs Centrosome Centriole Basal body Spindle pole body Myofibril Endosymbionts Mitochondrion Plastids Chloroplast Chromoplast Gerontoplast Leucoplast Amyloplast Elaioplast Proteinoplast Tannosome Other internal Nucleolus RNA Ribosome Spliceosome Vault Cytoplasm Cytosol Inclusions Proteasome External Undulipodium Cilium Flagellum Axoneme Radial spoke Extracellular matrix Cell wall Retrieved from `` https://en.wikipedia.org/w/index.php?title=Acrosome&oldid=821746103 '' Categories : Andrology Germ cell structures Secretory vesicles Animal reproductive system Hidden categories : All articles with unsourced statements Articles with unsourced statements from May 2016 Talk About Wikipedia Afrikaans Български Bosanski Català Čeština Deutsch Ελληνικά Español Français Galego 한국어 Қазақша Lietuvių 日本 語 Oʻzbekcha / ўзбекча Polski Português Română Русский Српски / srpski Srpskohrvatski / српскохрватски Svenska Tagalog ไทย Türkçe Українська 中文 19 more Edit links This page was last edited on 22 January 2018, at 11 : 09 ( UTC ). Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: the process by which the acrosome membranes of sperm break down is known as
Answer: acrosome reaction