[Spermatogenesis of Bothriocephalus clavibothrium Ariola, 1899 (Cestoda: Pseudophyllidea)].

The processes of spermatogenesis and spermiogenesis in the Pseudophyllidea Cestode Bothriocephalus clavibothrium were studied by light and electron microscopy. Spermatogenesis is for rosette type. The rosettes of secondary, tertiary and quaternary spermatogonia, primary and secondary spermatocytes and spermatid clusters are all resulting of a series of six incomplete, synchronous divisions (4 mitosis and 2 meiotic kinesis). The 64 nuclear syncytium of spermatids, during spermiogenesis process gives 64 mature spermatozoa, all originating from a single primary spermatogonium. The sperm differentiation is characterized by: 1. -- Formation of the differentiation zone containing an intercentriolar body and two basal bodies of the future axonemes; 2. -- Formation of a cytoplasmic expansion and induction of two flagella; 3. -- Migration of nucleus into medial cytoplasmic expansion inducing progressive longitudinal fusion of the later with two adjacent flagella into a single spermatozoon body. The filiforme spermatozoa of B. clavibothrium are about 300 micrometer long and their main components are . the nucleus, two axonemes, cortical microtubules and cytoplasm rich in beta-glycogen particles.