Ovariole

[1] Each ovariole is composed of a germarium (the germline stem cell niche) at the anterior tip, a set of developing oocytes contained within follicles, and a posterior connection to a common oviduct.

[2] These specialized cells provide nutrition and molecules important for embryonic patterning to the developing oocyte.

In telotrophic meroistic ovarioles, nurse cells are located in the germarium and connect to developing ooctypes via nutritive cords.

In the fruit fly Drosophila melanogaster, a common model organism for developmental research, each ovary typically contains between 16 and 20 polytrophic meroistic ovarioles.

[4] These ovarioles continuously produce eggs through division and differentiation of the germline stem cells, located in the anterior tip of the germarium.

Diagram of ovariole
A generalized insect ovariole of the panoistic type, showing the germarium, developing oocytpes in follicles, and the oviduct.
Diagram of ovariole types
Types of ovarioles: panoistic lack nurse cells, meroistic have nurse cells that are located either adjacent to the oocyte (polytrophic) or in the germarium (telotrophic).
diagram of the ovary of the fruit fly Drosophila melanogaster
A diagram of the ovary of the fruit fly Drosophila melanogaster , showing multiple ovarioles within the two ovaries, each containing multiple developing oocytes.