Abstract
In an electron microscopic study of the stigma of the unpollinated satsuma man darin flowers, it was revealed that the top surface of the stigma consisted histologically of papillary cells of various sizes and the underlying parenchymatous tissues. The surface of these papillary cells was covered with mucilaginous excretions. Cell walls of papillae were coated with cuticular layers which stretched inwards to a site just before the junction of the papillary and underlying parenchymatous cells.
Excretion of mucilaginous substances was effected by sporadic destruction and extinction of cuticular layers where some electron dense granules were formed. In these zones, a gradual transition was observed from degenerated electron dense granules to the frothy structure of mucilaginous excretions. This fact indicates that some substances deriving from decomposed membranous material were fused to granular bodies and further released into the ambient spaces through each breakage of cuticular layers.
In the papillary cells, marked swelling occurred on the sporadically rough-surfaced inner cell wall where the Golgi apparatus and several Golgi complex-derived vesicles seemed to function as active producers of cellulosic substances. Juvenile papillary cells were uninuclear and the nucleus was surrounded by chromoplasts containing several starch grains each. Some other organelles such as Golgi apparatus, mitochondria, ribosomes, vesicles, vacuoles, osmiophilic granules, rough-surfaced endoplasmic reticula, etc., were observed in the protoplast of papillary cells. Protoplasts of adjacent cells were connected with each other at their basal portions by the plasmodesmal strands.
