English: Figure 1 of paper

Cross-sections of the mature spermatozoon of Opisthomonorchis dinema observed in TEM.

• (A) Region I showing the anterior extremities of the two axonemes, the external ornamentation and cortical microtubules;
• (B and C) middle part of the region I exhibiting (B) both formed axonemes, the external ornamentation associated with cortical microtubules, spine-like body and attachment zones (C);
• (D and E) posterior part of the region I characterized by the appearance of the first mitochondrion and the cortical microtubule;
• (F and G) region II or transitional areas showing (F) the posterior part of the first mitochondrion, the axonemes and a decreasing number of cortical microtubules from about 10 to 5;
• (H) anterior part of the region III characterized by the disorganization of the first axoneme;
• (I) middle part of the region III characterized by the appearance of the second mitochondrion and the nucleus;
• (J) posterior part of the region III characterized by only the nucleus, one axoneme and cortical microtubules;
• (K and L) region IV corresponding to the posterior spermatozoon extremity. Note the disorganization of the second axoneme (K).

Scale bars: 0.2 µm. Arrowheads indicate attachment zones. Aae1, anterior extremity of first axoneme; Aae2, anterior extremity of second axoneme; Cm, cortical microtubules; Eo, external ornamentation of the plasma membrane; M1, first mitochondrion; M2, second mitochondrion; N, nucleus; Pae1, posterior extremity of axoneme 1; S, singlet of microtubule; Sb, spine-like body.