THREE-DIMENSIONAL OBSERVATION OF THE PROLAMELLAR BODIES IN ETIOPLASTS OF SQUASH CUCURBITA MOSCHATA.

The three-dimensional structure of the prolamellar bodies (PLBs) in etioplasts of squash Cucurbita Moschata Durch var melonaeformis Makino cv. Tokyo was observed with a high resolution scanning electron microscope (SEM). The PLBs isolated from etioplasts were fixed with osmium tetroxide, conductively stained with uranyl acetate, rapidly frozen in liquid Freon, and accordingly fractured in liquid nitrogen. To enhance the SEM image contrast of PLBs, the image processing method of Laplacian operator was performed, and the electron micrographs were processed using a digital processing system equipped with a scanning densitometer linked to a microcomputer. From these results a model, a combination of zincblende and wurtzite types closely related to Wehrmeyer's 'centric' type, was presented for the three-dimensional structure of PLB in squash Cucurbita moschata.