It should be noted that the intermingled somatic escort cells also have a critical role in the regulation of GSC self-renewal, cystoblast mitotic divisions, and cystocyte (also known as cyst cells) differentiation, as they secrete distinct signaling molecules (e.g., Hedgehog (Hh), Epidermal Growth Factor (EGF), Wingless (Wg), insulin, and ecdysone) whose function is crucial for the regulation of early oogenesis (Figure 2) [21,22,23,24,25,26,27,28]. The gene discussed is EGF; the disease is cyst.