Cytophysiological and ultrastructural modifications induced by cold in the microsporocytes and tapetum of Rhoeo discolor Hance

Abstract

The exposition of Rhoeo discolor to cold induces an alteration of the microsporocytes (PMC) and tapetum ultrastructure. In the young cooled PMC, the mitochondria present short and vesiculate cristae, the stroma of proplasts is clearer and the polyrilbasomes are deteriorated. During the phase tetrads-microspores, the alterations are more important: the chromatin coagulates, the nucleus swells while the nuclear membrane is modified; some large vesicules appear outside of the plasmalemma. In the cooled periplasmodium we can observe many groups of vesicules, mitochondria with dilated cristae, rough endoplasmic reticulum without their ribosomes and a breaking up of inueleoli. Our observations are in correlation with the previous results obtained by autoradiography and photometry, and are discussed with the bibliographical results.