TEM analyses of the development of the connecting piece in WT (left) and KO (right) sperm. TEM images represent ultrastructures of longitudinal sections of elongating spermatids (ES) and testicular sperm (TS) in WT and KO mice. An, annulus; BP, basal plates; Cp, capitulum; Mc, manchette; Mt, mitochondria; Nu, nucleus; PCV, proximal centriolar vault; PM, plasma membrane; SC, segmented column. Scale bar = 500 nm. 