SUBUNITS OF FORMING POLLEN EXINE AND UBISCH BODIES AS SEEN IN FREEZE-SUBSTITUTED LEDEBOURIA-SOCIALIS ROTH (HYACINTHACEAE)

High-pressure freezing/freeze substitution/TEM was employed to investi gate anthers of the monocotyledonous angiosperm Ledebouria socialis Ro th (Hyacinthaceae) during early tetrad stage. The initials of the oute r sporopollenous pollen wall stratum (= sexine) and of the homologous tapetal products (= Ubisch bodies) are composed of highly regular subu nits: clustered globules with a constant diameter of approximately 28 nm. The clusters develop within diffuse accumulations of electron-dens e material. This process, interpreted as sporopollenin polymerization, does not necessarily depend on the presence of membrane-bound enzymes . Immunogold labeling with JIM 5 and JIM 7 antibodies revealed that th e primexine as well as the dissolving tapetal cell walls, the sites of sexine and Ubisch body formation, respectively, contain un-esterified and methyl-esterified pectins.