Histochemistry and Ultrastructure of Suspensor Cells in Alyssum maritimum

Abstract

In Alyssum maritimum the zygote divides to form two cells namely the terminal cell and the basal cell. The basal cell, of the two-celled proembryo, stains less for proteins and RNA than the terminal cell. The derivatives of the basal cell form the suspensor cells of the proembryo and differ histochemically from the organogenetic part of the embryo derived from the terminal cell. The uppermost cell of the suspenson, towards the micropylar end, has been designated as `vesicular cell'. Electron microscopic investigations reveal the presence of wall ingrowths in the vesicular cell which acts as a transfer cell. All the suspensor cells of the embryo are interconnected through plasmodesmata. It is envisaged that the uppermost suspensor cell-vesicular cell-is responsible for the absorption and translocation of the metabolites in micropylar region of the embryo sac. The cell's position in the embryo sac and the peculiar morphology as revealed by EM studies are important adjuncts which enable this cell to mobilise the solutes towards the developing embryo.