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Fine structure of the nematocytes of Polypodium hydriforme Ussov (Cnidaria)
Author(s) -
RAIKOVA EKATERINA V.
Publication year - 1990
Publication title -
zoologica scripta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.204
H-Index - 64
eISSN - 1463-6409
pISSN - 0300-3256
DOI - 10.1111/j.1463-6409.1990.tb00236.x
Subject(s) - cnidocyte , nematocyst , biology , operculum (bryozoa) , cnidaria , coelenterata , anatomy , lernaean hydra , botany , zoology , ecology , microbiology and biotechnology , genus , coral
The fine structure of the stinging cells (nematocytes) and stinging capsules (nematocysts) is described for Polypodium hydriforme. a freshwater coclenterate with a prominent endoparasitie stage in its life cycle. All the nematocysts belong to the type of lesser glutinants (atrichous isorhiza) and fall into three size classes. The internal structure of the capsules is similar in the three classes. A novel type of organization of the cnidocil apparatus of the nematocysts is described. The cnidocil lacks a root fibre and its kinctosome sits directly on the operculum of the nematocyst, so that the entire cnidocil apparatus has a radial rather than bilateral symmetry. It is compared with that of other types of nematocytes and its similarity with the mechanoreccptors of the coelentcratcs is noted. The possible place of the Polypodium nematocytes in the evolution of the collar receptors of the Metazoa is discussed.