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Title: Development and roles of vitelline cells in eggshell formation in fasciola gigantica
Authors: Ardool Meepool
Chaitip Wanichanon
Vithoon Viyanant
Prasert Sobhon
Burapha University
Mahidol University
Thammasat University
Keywords: Agricultural and Biological Sciences;Biochemistry, Genetics and Molecular Biology
Issue Date: 1-Jan-2006
Citation: Invertebrate Reproduction and Development. Vol.49, No.1-2 (2006), 9-17
Abstract: In Fasciola gigantica, vitelline cells are the major contributors to the formation of the eggshell. The vitelline cells develop in vitelline follicles that are located in the posterior third of the adult parasite's body, in the areas lateral to the uterus and the testis. Mature vitelline cells are released and transported to the Mehlis' gland-ootype complex via a series of vitelline ducts. Based on ultrastructural features, the developing vitelline cells are classified into four stages: stem cell, protein-synthetic, carbohydrate-synthetic and mature cell stages. At the protein-synthetic stage, the eggshell globules are formed, whereas during the carbohydrate-synthetic stage glycogen particles and glycan vesicles are synthesized. The mature vitelline cells are detached from the nurse cells, and pass successively into the intrafollicular, interfollicular, longitudinal and transverse vitelline ducts, to be stored in the vitelline reservoir before being transported to the ootype via the median vitelline duct. At the same time, ova are transported from the ovary through the oviduct into the ootype lumen where each becomes surrounded by a number of vitelline cells. Vitelline cells secrete eggshell globules to surround a group of vitelline cells and an ovum in the ootype lumen, and these globules coalesce into the definitive eggshell. In the middle part of the uterus fertilization occurs, after which the eggshell is completely formed. Within the egg proper, vitelline cells break down, releasing glycogen and other products to nourish the developing embryo. © 2006 Taylor & Francis Group, LLC.
ISSN: 07924259
Appears in Collections:Scopus 2006-2010

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