Further observations on the in vitro development of the gametocytes of Plasmodium gallinaceum

Abstract

1. Gametocytes of Plasmodium gallinaceum emerged from the erythrocytes and the male gametocytes exflagellated normally in vitro, in normal or inactivated horse serum, or in rabbit plasma.2. Gametocytes, washed and suspended in normal horse serum, completed their sexual development and produced oocysts in mosquitoes.3. Hyperimmune chick plasma, as compared with normal chick plasma, did not significantly affect the time of onset or the frequency of exflagellation.4. In a solution, isotonic to bird blood and adjusted to approximately pH 8, containing NaCl, KC1, CaCl2, Na2HPO4, MgSO4, NaHCO3 and Tris buffer, the in vitro development of the gametocytes was normal, and the numbers developing were comparable to those in horse serum, or in plasma or serum from the normal host. The development of the gametocytes was inhibited by the omission of Na or HCO3 ions, but the omission of Mg, K, Ca, SO4 or HPO4 ions had no effect.5. Further experiments showed that the gametocytes emerged from the corpuscles and the males exflagellated normally in a solution containing only Na, C1 and HCO3 ions. Other combinations of ions were tested, but although gametocytes emerged from the corpuscles in some of these solutions, exflagellation either did not take place or did so infrequently, and the gametes produced were feeble in their movements. Within the range of inorganic salts tested, Na, HCO3 and C1 ions constituted the minimal requirement for the normal in vitro development of the male gametocytes.