Orchestina sp. 2 (Argentina)

SPERM TRANSFER FORM (fig. 29): Long, tubelike synspermia (fig. 29A), comprising two spermatozoa. The sheath that surrounds the sperm conjugates (,1 Mm) is formed in the deferent ducts (fig. 29B, C) and further condenses during the passage of the sperm conjugates toward the ejaculatory duct. Early sperm conjugates are oval shaped and further compress and elongate within the long deferent ducts. Fused sperm of a sperm conjugate are not coiled (fig. 29 E). Mitochondria are always present within the cytoplasm of the syncytium (fig. 29E).

SPERMATOZOA (fig. 29): Acrosomal complex: AV small, cylindrical (fig. 29E), and provided with a narrow subacrosomal space. AF originates from the subacrosomal space and extends into the NC (fig. 29D). Nucleus: prcN tubelike (fig. 29E) and provided with a very deep implantation fossa that extends as far as the anterior pole of the nucleus. The implantation fossa is filled with a large amount of an electron-dense centriolar adjunct (fig. 29 D–F). peN not developed (fig. 29F). NC located in the periphery of the prcN (fig. 29D). Axoneme: 9+3 microtubular pattern.

NOTES ON SPERMIOGENESIS: Information on spermiogenesis were not obtained due to missing material from the testis.