New aspects of spermatogenesis - Expression of mitochondrial marker proteins during spermatogenesis

Spermatogenesis is a highly complex, hormonally regulated cytodifferentiati on process finally leading to the production of spermatozoa, In addition to other events germ cell differentiation is characterized by a gradual struc tural modification of many organelles including mitochondria which play a u nique role. The morphological and functional development of germ cell mitoc hondria is a reflection of the permanent change in the testicular microenvi ronment which occurs when the germ cells are slowly moving from the base of the seminiferous epithelium to the lumen. Concomitant with the structural changes, several mitochondrial proteins are known to be expressed and synth esized during distinct phases of the organelle's development. This review p ays particular attention to these transiently expressed mitochondrial prote ins such as hsp60, Lon protease, sulphydryl oxidase and cytochrome ct. Furt hermore, the biological function of this stepwise gene activation during mi tochondrial and germ cell development is discussed.