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An Ultrastructural Study of the Spermatozoa from Prionospio cf. queenslandica and Tripolydora sp.: Two Spionid Polychaetes with Different Reproductive Methods
Author(s) -
Rouse G. W.
Publication year - 1988
Publication title -
acta zoologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.414
H-Index - 37
eISSN - 1463-6395
pISSN - 0001-7272
DOI - 10.1111/j.1463-6395.1988.tb00917.x
Subject(s) - spermatozoon , axoneme , centriole , biology , flagellum , acrosome , nucleus , ultrastructure , sperm , anatomy , microbiology and biotechnology , annulus (botany) , semen , botany , paleontology , bacteria
The fine structure of the spermatozoa of two spionids is described. The spermatozoon of Prionospio cf. queenslandica is typical of an animal utilizing external fertilization, in having a subspheroidal nucleus, a midpiece composed of unmodified rounded mitochondria surrounding two centrioles and a free flagellum. The acrosome is unusual in showing bilateral symmetry. The spermatozoon of Tripolydora sp. resembles that of spionids utilizing spermatophores, in possessing an extremely elongate nucleus and midpiece. The nucleus is penetrated by the 9+2 axoneme for its entire length, linking with a single centriole at the anterior end. Platelets surround the nucleus and intermingle with the mitochondria of the midpiece, which terminates with an annulus. The acrosome shows some internal vesiculation and substructuring. Sperm structure in relation to reproductive methods is discussed and the view of external fertilization as primitive is questioned.