idiozome

from The Century Dictionary.

• noun A body in the spermatids of animals, supposed, in some cases, to be concerned in the formation of the acrosome and the middle-piece of the spermatozoön, and in others to disappear without giving rise to any portion of the spermatozoön. Theidiozome is sometimes regarded as the equivalent of the attraction-sphere of other cells besides the spermatids.