Re: What is an acrosome?

The acrosome is a specialized structure that is inside the tip of the sperm cell. It is derived from the Golgi complex during the maturation of the sperm. It is basically a storage vesicle that contains a variety of enzymes that digest proteins and complex sugars. The contents of the acrosome are secreted once the sperm contacts the egg ( in a process known as Acrosomal Reaction). During the Acrosomal Reaction, the acrosome fuses with the sperm membrane (Exocytosis), which results in the release of the contents in the acrosome into the sperm's surroundings. These enzymes will break down the zona pellucida that envelopes the egg, forming a thin path that allows the sperm to approach the egg and fuse with its cytoplasm. For a general review on the process of fertilization, try: Fertilization in mammals. By Wassarman PM in Scientific American 1988 Dec;259(6):78-84. For more specific information on what triggers the Acrosomal Reaction in mammals: http://zygote.swarthmore.edu /fert5.html