The mitochondrial derivative of the spermatozoon of Drosophila before and after fertilization

Abstract

The ultrastructure of the paracrystalline mitochondrial derivative of the Drosophila spermatozoon has been investigated in sperms stored for different intervals after mating within the genital apparatus of inseminated females and in sperms which penetrated the egg. The paracrystalline lattice remains structurally intact even after the most prolonged storage. Only after fertilization does the derivative exhibit structural modifications which following a characteristic pattern lead to the formation of lamellar bodies present up to the onset of the cellular blastoderm stage of the egg development. The behaviour of the mitochondrial derivative during the sperm storage, its fate at fertilization, and the absence of cytochrome c oxidase activity from its crystalline texture, as demonstrated by cytochemical tests, suggest that the typical biochemical activity of mitochondria is not a major function of this highly differentiated sperm component. The functional significance of the derivative is discussed in relation to a possible role at fertilization and to sperm metabolism.