THE STRUCTURE OF LEISHMANIA TROPICA AS REVEALED BY PHASE AND ELECTRON MICROSCOPY

Abstract

The structural details were studied by 3 methods: (1) Living, unstained cultures were observed with the phase microscope. (2) Films of the organisms were stained with both Giemsa and Wright stains and examined at a magnification of 1350X. (3) The organisms were suspended in distilled water, allowed to swell, and at suitable intervals samples were removed and studied with the electron microscope. In young cultures, the flagella of most of the organisms were little more than short protrusions of their axonemes. But after 7 days, many of the cells had long, laminated flagella that sometimes were fragmented longitudinally. The blepharoplast from which the flagellum arose was a spherical structure with a definite limiting membrane. The nucleus of the cell normally appeared opaque to the electron beam, but as a result of plasmoptysis it had increased 6-8 times in size, dispersing the nuclear material sufficiently to reveal the round karyosome typical of the resting nucleus. The cell wall of the leishmania appeared homogeneous when examined with the phase microscope; however, fine, longitudinal striations were seen with the electron microscope. Plasmoptysis of the cell caused the structures to spread apart; and in cells that had burst from the pressure, the longitudinal fibrils were seen to be connected by a thin, elastic membrane.