from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A caplike structure at the anterior end of a spermatozoon that produces enzymes aiding in egg penetration.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A structure forming the end of the head of a spermatozoon.
from The Century Dictionary and Cyclopedia
- n. In cytology, the body which forms the extreme anterior portion of the spermatozoön. Von Lenhossek, 1897.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a process at the anterior end of a sperm cell that produces enzymes to facilitate penetration of the egg
In order to accomplish this the head of each sperm called the acrosome contains a packet of shell-dissolving enzymes—released when contact with the egg is made.
As researchers from the University of Illinois explain it, normal sperm are composed of a cap-like structure that surrounds the anterior end of the sperm head called the acrosome.
The acrosome is a large membrane-limited granule that overlies the nucleus of mature sperm
The acrosome is the packet of enzymes in the sperm’s head that produces enzymes to facilitate penetration of the egg.
The acrosome reaction is the chemical change that enables a sperm to penetrate an egg.
However, the amount of Viagra at concentrations equivalent to what a man would have thirty minutes after taking the maximum recommended 100 milligram dose leads to early activation of the acrosome reaction.
If sperm undergo the acrosome reaction too early, before they contact the egg, they are incapable of fertilization.
So if the majority of sperm undergo the acrosome reaction on exposure to Viagra, the drug may significantly impair their fertilizing potential.
They found that while the Viagra-bathed sperm became more active, they also suffered damage to the structure at their heads known as the acrosome.
Only after the capacitation is completed can the spermatozoa respond to the oocyte interaction with the exocytosis of acrosome content, the acrosome reaction (AR).