Germinal development in embryonic rediae of the hemiuroid digenean Bunocotyle progenetica: an ultrastructural study

Podvyaznaya, I.M.; Галактионов, К. В.

doi:10.1007/s00436-021-07349-8

Cited by 1 publication

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“…At the same time, the mother sporocysts of B. progenetica may live for a fairly long time by the standards of this life-cycle stage (up to six months), their life span depending on the season when the mollusc has been infected (Levakin 2008). These parthenitae can overwinter in the body of the host; during this time they retain the ability to move actively, and the process of development of redial embryos continues in their brood cavity (Podvyaznaya and Galaktionov 2021). Apparently, this would have been impossible without the continued trophic function of the tegument.…”

Section: Discussionmentioning

confidence: 99%

Tegument ultrastructure in mother sporocysts of Bunocotyle progenetica (Markowski, 1936) Chabaud et Buttner, 1959 (Digenea: Hemiuridae)

Podvyaznaya,

Filimonova

2024

Proceedings ZIN

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This paper focuses on the fine structure of mother sporocysts, the least studied stage of the digenean life cycle. The ultrastructure of the tegument of mature mother sporocysts of Bunocotyle progenetica was examined by transmission electron microscopy and described in detail. The tegument of these parthenitae is represented by an outer anucleate syncytium connected with the deeper-lying tegumental cells by cytoplasmic bridges. Its outer plasma membrane forms minute leaf-like outgrowths and numerous deep invaginations in the shape of interconnected channels. These channels, which pass in various directions and permeate almost the entire outer syncytium, considerably amplify its surface area. The cytoplasm of the outer layer of the tegument contains large mitochondria, microtubules and rare dense secretory granules, whose contents are discharged into the lumen of the channels. Numerous pinocytotic vesicles originate from the plasma membrane of the channels. Small endocytic vesicles are transported along the cytoplasmic bridges to the tegumental cells, where endocytosed food material is sorted and broken down. These cells are characterized by a well-developed Golgi apparatus, which is represented by multiple stacks of cisternae, and the presence of numerous endosomes at different maturation stages and residual bodies. Some steps of endosomal maturation in the tegumental cells were traced. In addition to their digestive activity, tegumental cells produce secretory granules, which are transported to the outer syncytium after their maturation. It was shown for the first time that in mature parthenitae, the population of tegumental cells could be renewed at the expense of a reserve pool of undifferentiated cells. The ultrastructural features of the tegument of mother sporocysts of B. progenetica are discussed in light of the concept of the enhanced trophic function of the tegument in sporocysts lacking the alimentary canal.

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Section: Discussionmentioning

confidence: 99%