Some organelles of watermelon microspores were observed by using transmission electron microscope.Ribosome density was high in tetrad microspores, very low in vacuoli zing ones,and high again after vacuolization came to an end.Mitochondria showed a cycle of dedifferentiation and redifferentiation.Disappearance of mitochondrial cristae and decrease of such organelle number during vacuolization stage were implications of the dedifferentiation,and reappearance of cristae and a variety of variations in sha...