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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 7716

Karl G. Grell and Anne Meister; [Beitrage zur Ultrastruktur der Konjugation von Ephelota gemmipara R. Hertwig (Suctoria)]. Protistologica XX(1):65-86, 1984

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1. During conjugation of the suctorian Ephelota gemmipara the two cells mating with each other (gamonts) behave differently (anisogamonty). The so-called macrogamont remains attached to its stalk, the so-called microgamont become detached from it. The macrogamont produces the stationary nucleus, the microgamont the migratory nucleus. Both nuclei fuse within the macrogamont to form the synkaryon. During the mating process the microgamont becomes resorbed for its most part by the macrogamont. 2. Both cells are separated during mating by the "conjugants' boundary". Our electronmicroscopical investigations prove that the conjugants' boundary in Ephelota gemmipara originates by transformation of the epiplasmic layer of the microgamont, while the epiplasmic layer of the macrogamont does not participate in its formation but gets dissolved. 3. The transformation of the epiplasmic layer into the conjugants' boundary leads to an ultrastructure which can be called << spongy >>: It becomes traversed by a system of communicating lacunes separated by walls of optical density. 4. During conjugation of the suctorian Heliophrya erhardi the two cells mating with each other have equally (isogamonty). Each gamont forms a stationary and a migratory nucleus. As in most ciliates a reciprocal fertilization occurs. Since the conjugant' boundary originates by the transformation of both gamonts in this case (Lanners, 1978), we suppose that the capability to transform the epiplasmic layer into the conjugants'boundary is correlated with the existence of the migratory nucleus. 5. The occasional occurrence of abortive pronuclei being stuck within the conjugants' boundary, speaks for the assumption that sometimes a postmeiotic division occurs in the microgamont leading to the formation of two migratory nuclei.