(A–E) Transmission electron micrographs of region IV (posterior region) of the mature spermatozoon of Tergestia clonacantha. Scale bars = 0.2 μm. Cross-sections in region IV of mature spermatozoon of Tergestia clonacantha showing the appearance of the second mitochondrion (M2) (A), then the nucleus (N) (B). (C) Cross-sections showing the disappearance of the first mitochondrion, a progressive disappearance of microtubules (C–D) and axoneme 2 (E). Then, the posterior extremity of the spermatozoon exhibiting only the nucleus (E). (F–G) Transmission electron micrographs showing many sections of the mature spermatozoon of Tergestia clonacantha with granules of glycogen (G) highlighted by the Thiéry method. Scale bars = 0.5 μm.