Topographical relations between oocytes and other ovarian cells in three mite species (Acari)
1987 - Volume: 28 Issue: 4 pages: 297-306
KeywordsOocyte-ovary attachment stalk cells ovary Acari
Ultrastructural observations of oocyte-ovary attachment in three mite species have been presented. In Euryparasitus emarginatus (Gamasida), the broad stalk is composed of two cell types: central and parietal. The oocyte adheres to central cells via the micropylar orifice in the vitelline envelope. At the site of contact, numerous spherical protrusions of oocyte interdigitale with invaginations of the central cells. In Erythraeus pha/angoides (Actinedida) the oocytes are placed on distinct stalks composed of four cellular elements: ( 1) pear-shapec! main stalk cells which surround (2) the centrally running microtubule containing probably nutritive, protrusion (3) border cells which separate the stalk from the rest of ovary, and (4) scarce muscle cells twining around the stalk. Through the micropylar orifice passes a nutritive protrusion which connects oocyte with multinucleate nutritive cell embedded in the ovarian wall. In Hafenrefferia gi/vipes (Oribatida) only oogonia and previtellogenic oocytes possess microtubule-rich protrusions which join each other to form anucleate, microtubule-rich central mass. Possible functions of stalks and attachment sites are discussed.
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