Fig. 7. Schematic representation of blood cell fate resolution during Drosophila embryogenesis. Initially all the prohemocytes express gcm but not lz. Then gcm transcription is turned off and lz expression activated in the first row of prohemocytes but not in the others that subsequently differentiate into plasmatocytes. 60% of these lz⁺ progenitors manage to maintain lz expression through an autoactivation loop and differentiate into crystal cells, while in the remaining 40%, the presence of residual GCM interferes with lz expression and promotes plasmatocyte differentiation. In the absence of gcm/gcm2, more prohemocytes (potentially the second row) initiate lz expression and all the lz⁺ progenitors differentiate into crystal cells.