Abstract
To investigate the mechanisms causing male sterility of four Cryptomeria japonica D.Don individuals (Fukushima-1, Fukushima-2, Shindai-11, and Shindai-12), histological information was collected using light, fluorescence, scanning electron and transmission electron microscopes. In the four sterile males, the tetrads developed just as for fertile individuals in the microspore formation process. However, they did not release any microspores after callose dissolution because the microspores adhered to each other, and showed no pollen dispersal. In these sterile males, each microspore adhered partially since proendexine of the exine was not developed, though it generally develops during the period when microspores are enclosed by the callose wall. The release of the Ubisch bodies from the tapetum was not observed after callose dissolution, and the amount of translucent amorphous substances gradually increased. Our results suggested that the male sterility of these C. japonica individuals was caused by abnormal behaviors of microspore cytoplasm and tapetum without normal supply of the substances that compose the exine of the pollen wall.
