Fig 1 Progression of the schizont stages during the intracellular development of Sarcocystis neurona expressing yellow fluorescent protein. Post-invasion, the merozoites convert into schizonts that progressively develop into early-, mid-, and late-schizonts while undergoing a form of asexual reproduction called endopolygeny. In the final step in endopolygeny, the mature schizont forms 64 haploid merozoites fully equipped to egress and invade new host cells. S. neurona, Sn; DAPI-stained host cell nuclei, HCN.