In setting up the compass points of the egg, the microtubules exchange signals with follicle cells that surround the egg.

Analysis of the follicle cells showed the Sonic hedgehog gene was active in the injected areas of the skin but not elsewhere.

The follicle cells are now a progesterone secreting structure known as the corpus luteum.

In contrast to the anterior and the posterior, the positional information for the terminalia come from the follicle cells of the ovary.

The follicle cells secrete Torso-like into the perivitelline space only at the poles.

This side sends a signal, gurken, to the torpedo receptors on the follicle cells.

The follicle cells change shape and synthetic properties to distinguish the dorsal side from the ventral side.

The second step is a signal from the ventral follicle cells back to the oocyte.

The follicle cells secrete windbeutel, nudel, and pipe, which create a protease-activating complex.

A few follicle cells are stimulated to grow but only one oocyte is ovulated.