Yolk stick
The germ yolk floor (Germovitellarium or Vitellogermarium; lat. To "germen" - the "seed" and vitellus - the "yolk") is an in various animal groups, especially the turbellaria and some rotifers occurring (Rotatoria) form of female gonad . It is one of cells of the ovary (ovary) and cells of the yolk cane (vitellarium) and thus a heterocellular structure.
function
The germovitellarium forms germocytes (developable germ cells) and vitellocytes ( non- developable nutrient cells, which contain nutrient and shell substances), i.e. eggs composed of egg and yolk.
The germinal yolk of flatworms evolved from a simple ovary that not only forms egg cells but also yolk material. The yolk cells are interpreted as so-called arbotive eggs, i.e. egg cells that are not fully developed and are only formed as nutrient material. In further derived forms of flatworms, the ovary and yolk are completely separate.
Individual evidence
- ↑ Keyword "Mantelhöhle" in: Herder-Lexikon der Biologie. Spectrum Akademischer Verlag GmbH, Heidelberg 2003. ISBN 3-8274-0354-5 .
- ↑ a b c Keyword "Dotterstock" in: Herder-Lexikon der Biologie. Spectrum Akademischer Verlag GmbH, Heidelberg 2003. ISBN 3-8274-0354-5 .