Germline-stem cells (GSCs) produce gametes and are thus true "immortal stem cells". In Drosophila ovaries. GSCs divide asymmetrically to produce daughter GSCs and cystoblasts. and the latter differentiate into germline cysts. https://www.ngetikin.com/quick-offer-1-Gallon-Universal-Primer-Pro-Deep-Penetrating-Primer-big-deal/