noun, plural: gametocytes
A gamete-forming diploid germ cell
A gametocyte is a gamete-forming cell. In humans and other higher forms of animals, there are two types of gametocytes: spermatocytes (male gametocytes) and oocytes (female gametocytes). These gametocytes arise from gametogonia (particularly, spermatogonia and oogonia). The gametogonia develop into gametocytes through a process called gametocytogenesis. A gametocyte, in turn, gives rise to gametes through gametogenesis. The gametocyte is a diploid germ cell to begin with but when it undergoes meiosis (via gametogenesis) it produces genetically variable haploid sex cells, i.e. sperm cell in males and ovum in females.
In lower forms of animal, Apicomplexa in particular, the gametocyte is one of the many cell types during their life cycle. Apicomplexa is a phylum comprised of protozoans. They are mostly single-celled, parasitic, and spore-forming. Their life cycle is comprised of stages where each has a particular cellular variety. Nevertheless, not all members have all the various life stages. Taking for instance the life cycle of Plasmodium falciparum, one of the major causative agents of malaria in humans. In a human host, this species demonstrates these cell stages: merozoite, trophozoite, schizont, and gametocyte stages. In the erythrocytic stage, some merozoites develop into gametocytes through a process gametocytogenesis. The male gametocyte differentiates into a microgamete whereas the female gametocyte differentiates into a macrogamete.
Word origin: Greek gametēs ("partner") + kytos ("cell")