Ovary organization and ultrastructure in six species of Amynthas and Metaphire earthworms (Annelida, Crassiclitellata, Megascolecidae)

• DOI: 10.1016/j.zool.2023.126109
• Publication Date: 2023-08-10T08:28:09Z
• Authors: Piotr Świątek; Rojen Singh Thoun...; Th. Binoy Singh; Samuel James; Łukasz Gajda; Karol Małota; Dominika Raś; Anna Z. Urbisz
• Keywords: Nurse cell

Ovaries in earthworms belonging to the family Megascolecidae are paired structures attached septum anterior part of XIII segment. They fan rosette shaped with numerous rows growing oocytes, known as egg strings, radiating from ovary center towards segmental cavity. The histological and ultrastructural organization megascolecids course oogenesis remain unknown. paper presents results light electron microscopy analyses ovaries six megascolecid species, three genus Amynthas Metaphire. Both parthenogenetic sexually reproducing species were included study. ultrastructure all studied broadly similar. Considering ovaries, they could be divided into two zones. Zone I (proximal, close connection septum) is tightly packed germline somatic cells. Germ cells interconnected via intercellular bridges thin strands central cytoplasm (known cytophore) form syncytial cysts. Cysts unite oogonia, early meiotic (till diplotene), clustering develop synchronously. During diplotene, lose developmental synchrony; most probably, one cell per cyst grows faster than others, detaches cysts, becomes an oocyte. remaining grow slightly still reticular cytophore; these considered nurse II has a strings where oocytes isolated another by short cords. We present details propose term "Amynthas" type for this organization. suppose that such characteristic other related families.