Cinetomorpha sp. (Iguazú)

SPERM TRANSFER FORM (figs. 3, 4): Large, cone-shaped synspermia (,25 Mm) consisting of four fused spermatozoa (fig. 3);

irregular membranes located in the periphery (fig. 4 A–C). Cytoplasm in sperm conjugate heterogeneous; some dense granules and lamellae occur (fig. 4 A–C, G). Nuclei incompletely coiled and helically contorted, chromatin irregularly condensed (fig. 4D, E). Axonemes hardly visible (fig. 4F) due a low electron density compared to the nonhomogeneous cytoplasm. A thin (, 80 nm) secretion sheath, developed in the deferent ducts, surrounds each sperm conjugate (fig. 4G).

SPERMATOZOA (fig. 4): Acrosomal complex: AV cylindrical and small (,4.9 Mm); narrow subacrosomal space for the most part, slightly widening posteriorly (fig. 4E, 4E inset). AF thin, originates from narrow subacrosomal space in anterior AV and extends into a nuclear canal, but clearly ends before axonemal base. Nucleus: prcN elongated (,66.8 Mm) (fig. 4 A–C), helically contorted, and with a conspicuous, irregular chromatin-condensation pattern. The small implantation fossa contains only centrioles (fig. 4G); peN absent. NC empty for the most part in mid and late spermatids and no longer visible in mature sperm. Axoneme: 9+3 microtubular pattern.

NOTES ON SPERMIOGENESIS (fig. 5): Within the testis all stages of spermiogenesis are present. Germ cells of the same developmental stage in conjunction within cyst. The acrosomal vacuole of early spermatids irregularly electron dense, resulting in spotted appearance (fig. 5A). It is separated from the anterior pole of the nucleus by a small electron-dense plate. The two centrioles migrate toward posterior pole, where they arrange in a tandem position (fig. 5B). Chromatin starts to condense only in a small portion near the nuclear canal that contains the acrosomal filament (fig. 5C, D) while the so-called manchette of microtubules (i.e., a ring or ruffle of microtubules) surrounds the entire nuclear material (fig. 5C, D). Further development includes elongation of the nucleus. The chromatin condenses irregularly and appears “folded” (fig. 5E) with a typical “looped” appearance in cross section (fig. 5E, H). Although the axoneme has the typical 9+3 microtubular pattern (fig. 5F), the central tubuli are very short, thus the main part of the axoneme shows 9+0 microtubular pattern (fig. 5G). While spermatids start to fuse at the end of spermiogenesis, the manchette of microtubules disintegrates (fig. 5H).