Abstract Using monoclonal antibodies (mAbs) JIM13, JIM15 and MAC207, we investigated the temporal and spatial dis-tribution of some arabinogalactan protein (AGP) epitopes in cells of the Bellis perennis L. anther at different developmental stages. AGP epitopes recognized by JIM13 were detected in the protoplasts of tapetal cells, dividing microsporocytes, and microspores; AGP epitopes recognized by JIM15 were present in the cytoplasm of tapetal cells only at the stage with tetrads of microspores in the anther loculus. AGP epitopes recognized by MAC207 were present in the cells of different somatic tissues of the flower bud, but after asymmetric mitosis in the microspore they appeared abundantly in the protoplasts of immature pollen and were still present in mature pollen grains. Callose, revealed by mAb, appeared at the same stage of microsporocyte division as AGPs labelled with JIM13 and JIM15. We discuss the differences in callose and AGP localization and the possible role of the latter during anther development.

The development of megasporocytes and the functional megaspore formation in Deschampsia antarctica were analyzed with the use of microscopic methods. A single archesporial cell was formed directly under the epidermis in the micropylar region of the ovule without producing a parietal cell. In successive stages of development, the meiocyte was transformed into a megaspore tetrad after meiosis. Most megaspores were arranged in a linear fashion, but some tetrads were T-shaped. Only one of the 60 analyzed ovules contained a cell in the direct proximity of the megasporocyte, which could be an aposporous initial. Most of the evaluated D. antarctica ovules featured monosporic embryo sacs of the Polygonum type. Approximately 30% of ovules contained numerous megaspores that were enlarged. The megaspores were located at chalazal and micropylar poles, and some ovules featured two megaspores - terminal and medial - in the chalazal region, or even three megaspores at the chalazal pole. In those cases, the micropylar megaspore was significantly smaller than the remaining megaspores, and it did not have the characteristic features of functional megaspores. Meiocytes and megaspores of D. antarctica contained polysaccharides that were detectable by PAS-reaction and aniline blue staining. Starch granules and cell walls of megasporocytes, megaspores and nucellar cells were PAS-positive. Fluorescent callose deposits were identified in the micropylar end of the megasporocytes. During meiosis and after its completion, thick callose deposits were also visible in the periclinal walls and in a small amount in the anticlinal walls of megaspores forming linear and T-shaped tetrads. Callose deposits fluorescence was not observed in the walls of the nucellar cells.