Abstract
The surface feature on the initiation and development of callus, derived from coffee (Coffea arabica L. var. typica) leaf explants, was examined by scanning electron microscope (SENI). After about two weeks of culture, callus emerged mainly from cut leaf edges. After about 45 days, these callus masses turned into soft and translucent tissues which were like an assembly of numerous threads at a stereomicroscopical view. Ultrastructural observations by SENI revealed that callus proliferation mainly occurred from mesophyll cells near vascular bundles of cut leaf explants. A membranous layer covering the callus surface was broken by some ruptures at several places, and superficial cells appeared underneath the fragmented membrane. Furthermore, interesting morphology of the callus surface was revealed: spherical cells, elongated cells, and cylindrically elongated or curled cells were present.
