part of develops from develops into head mesoderm developing embryonic structure prohemocyte embryonic hemocyte primordium Morphologically-distinguishable head mesoderm region that gives rise to prohemocytes, dividing until embryonic stage 12 (Evans et al., 2003). These prohemocytes differentiate by the end of embryogenesis, with most plasmatocytes migrating to other parts of the embryo and most crystal cells remaining close to their point of origin (Evans et al., 2003). FBbt:00005247 fly_anatomy.ontology embryonic haemocyte primordium primordium embryonic hemocyte anlage head mesoderm derivative