الفهرس 
Terrestrial snails in EgyptOnly 14 pages are availabe for public view
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Abstract
The present study deals with the ultrastructure of the mature spermatozoa of seven species of the phylum Mollusca. These species are four terrestrial and three freshwater pulmonate gastropods. They were involved in this investigation as they have economic and medical importance where they have become significant as agricultural pests and as vectors of parasites. Thus, the effect of some biocompounds or plant extracts was examined on the mortality of these snails and on the ultrastructure of their mature spermatozoa. The biocompounds were extracted from the following plants: Calotropis procera, Pelargonium graveolens, Ethulia conyzoides and Euphorbia milii. From the present investigation it was concluded that the ultrastructure of the spermatozoa of the examined snails are of the modified type. Most of them have a complex midpiece composed of mitochondrial derivative and one or more glycogen helix thus, these spermatozoa are highly motile and its ultrastructure can be easily used for the differentiation between the different species of pulmonate gastropods. Using of some plant extracts as environmentally safe natural molluscicides leading to mortality and infertility of a live pulmonate snail can be considered as a new way to control the land and the freshwater snails specially those, which are agricultural pests and the main intermediate hosts for several parasites.