Localization of Cytoplasmic Lactate Dehydrogenase-X in Spermatozoa

Abstract
Cytoplasmic lactate dehydrogenase-X (LDH-X) has been localized in the tail sheath of mature intact mouse, human, and rat spermatozoa by histochemical and immunological techniques. The isozyme is also found within the mitochondria. Intact sperm demonstrate a mitochondrial LDH-X but cytoplasmic localization in mature sperm cells has been inconclusive. The presence of LDH-X in the sperm tail supports in vitro biochemical data for the existence of a cytosol/mitochondria shuttle of reducing equivalents mediated by LDH-X.