Functional Role of Vitelline Glands and Mehlis Gland in the Process of Resistant Egg Shell Formation in Trematodes

Abstract

The study of the functional morphology of the reproductive system of trematodes, as well as its individual parts, provides an opportunity to solve an important problem that plays a huge role in theoretical and practical terms as the directed regulation of the fecundity of endoparasites. The article is devoted to the study of the functional role of vitelline glands and Mehlis glands in the process of formation of resistant egg shells on the example of the Parastrigea robusta trematode. The functional mechanisms are revealed on the basis of histomorphological and ultrastructural studies, underlying the provision of trematode eggshell formation processes and the role of each of the mentioned departments. The sequence of appearance and maturation of shell material in the vitelline follicles during vitellogenesis has been determined. The role of the Mehlis gland is substantiated on the basis of electron microscopy methods and their functional morphological analysis of ultrastructural and micromorphological data. The obtained data reveals information on the structural and functional unity of the mechanisms underlying the formation of a resistant trematode eggshell, the role of vitelline glands, and Mehlis gland in providing a "large number of eggs". According to the results of histological and electron microscopic studies of vitelline glands and Mehlis gland of the Parastrigea robusta trematode, a general scheme of the formation of trematode eggshell was formed. As a result, the obtained knowledge on the peculiarities of the structure and maturation of the vitelline glands and Mehlis gland of Parastrigea robusta will significantly complement the knowledge on the structural features of the female reproductive system of trematodes and the fertility of endoparasites. The results of the work can be used for further research in the selection of anthelmintic agents that affect vitelline glands and Mehlis glands, which will lead to directed regulation of the fertility level of endoparasites.