germarium

The germarium is the egg-producing part of the ovary in many flatworms and rotifers, and it can also refer to the corresponding part of a testis. In insects, each ovary is composed of ovarioles, which lead to oviducts. Each ovariole contains a germarium and a series of ovarian follicles. The germarium is a cluster of undifferentiated cells that develop into oocytes, nurse cells, and follicular cells. These cells are crucial for nourishing the developing oocytes and forming the eggshell. The gonads themselves, including ovaries and testes, are of mesodermal origin.123