5 TYPES OF COLLOBLAST IN A CYDIPPID CTENOPHORE, MINICTENA-LUTEOLA CARRE AND CARRE - AN ULTRASTRUCTURAL-STUDY AND CYTOLOGICAL INTERPRETATION

Minictena luteola Carre and Carre is a recently described, small medit erranean ctenophore, with five types of colloblast. We have examined t he morphology of the colloblasts at different stages of differentiatio n by electron microscopy. The five types differ in size and structure at all stages of differentiation. This is the first report of collobla st polymorphism in ctenophores. Two of the types found in M. luteola d iffer significantly from the generally accepted structure of colloblas ts, in particular by the absence of refractive vesicles. Examination o f the structure of the five types of colloblast during differentiation has given us a better idea of the nature and organization of the axia l filament and the origin of the spheroidal body and its relationship with the nucleus. Our observations lead us to question the axonemal na ture of the spiral filament.