STRUCTURE OF TAPETAL CELLS OF BARLEY (HORDEUM VULGARE L.)

Tapetal cells, like other parietal layer cells were small and oblong in the beginning. Shortly afterwards they incvcased in size and became binucleate, their cytoplasm being densely staincd with haematoxylin. Not a fow cells of the tapetum showed chromatin qranules in their nuclei. At the pollen tetrad stage, the tapetal cells had attained their maximum growth. The submicroscopic structure of the tapetal cells of the barley anthers has been investigated at the stages of a late tetrad and uninucleate pollen qrain before and after vacuolization. The tapetal cells of the barley as regards their structure and functions at these stages of development may be characterized as secretary ones. Their cytoplasm is abundant with cell organells. Numerous mitochondria and a Golgi apparatus are in close vicinity with the cisterns of an endoplasmic reticulum. The presence of ribosomes on the onter cisternae of the stack relates the entire structure to the endoplasmic reticulum. Ocmiophilic substances apper in several places with respect to the tapetal cells. At the stage of an uninucleate pollen grain instead of the degenerated primary walls, surrounding every tapetal cell, a new wall is formed, which consists mainly of sporopollenin.