, Volume 124, Issue 1, pp 33-46
Date: 22 Feb 2005

Morphogenesis of Paragordius varius (Nematomorpha) during the parasitic phase

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The development of Paragordius varius (Nematomorpha), in the parasitic phase of the life cycle, was followed ultrastructurally from 10 days after controlled infection of crickets (Gryllus firmus) to mature animals at 30 days after infection. During this time span, specimens grow from about 1 cm to more than 10 cm and from 93 μm to about 400 μm in diameter. A thin larval cuticle is replaced at about day 20 by a robust adult cuticle. Epidermis and intestine appear physiologically active during the early stages, but decrease in size and cytological components during further development. This is probably connected to the uptake of nutrients through the larval cuticle, whereas the adult cuticle has only protective function. The longitudinal musculature grows continuously and changes from fewer platymyarian cells to abundant coelomyarian cells. The ventral nerve cord shifts from an intraepidermal to a submuscular position during development. Additionally, basiepidermal nerves are present. Gonads develop from paired dorsolateral compact strands. It seems that in males, cells within these strands separate into epithelial and central cells, which become the gametes, while in females, gametes proliferate from the strands into the primary body cavity and fill it up completely. In males, there is a large quantity of parenchyma, restricting the body cavity to a small periintestinal space, while in females, parenchyma occurs only in the periphery of the gametes.