Spermatogenesis and sperm ultrastructure in the interstitial syllid Petitia amphophthalma (Annelida, Polychaeta)

Autor(en): Buhrmann, C
Westheide, W
Purschke, G 
Stichwörter: HESIONIDAE; Marine & Freshwater Biology; MORPHOLOGY; REPRODUCTIVE-BIOLOGY; SABELLIDAE; SPECIES POLYCHAETA; SPERMATOZOA; SPERMIOGENESIS; SYSTEMATICS
Erscheinungsdatum: 1996
Herausgeber: OPHELIA PUBLICATIONS
Journal: OPHELIA
Volumen: 45
Ausgabe: 2
Startseite: 81
Seitenende: 100
Zusammenfassung: 
The interstitial syllid Petitia amphophthalma is gonochoristic. The mature spermatozoa accumulate in the dorsal region of a seminar vesicle that extends over several segments. TEM studies have shown them to be filiform spermatozoa of the so-called modified type (35 mu m long) typical of many interstitial polychaetes with internal fertilization: the head comprises two elongated elements, the acrosome (ca. 8 mu m long) and a nucleus (only half as long, ca. 3 mu m) into which the basal part of the axoneme of the flagellum projects; in the adjacent midpiece of identical diameter (0.6 mu m) the axoneme is surrounded by two mitochondrial complexes over 16 mu m of its length; the spermatozoon terminates in a tail (ca. 10 mu m long) consisting of the axoneme alone. Spermatogenesis occurs in the ventral region of the vesicle. The gametes differentiate into morulae, which form a cytophore after the second maturation division. Striking features of both primary and secondary spermatocytes is the presence of two pairs of centrioles together with a short flagellum. They are unique to the Syllidae and extremely rare within the animal kingdom.
ISSN: 00785326

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