Microspore Mother Cell Stage Research Articles

Sporogenesis and Gametogenesis in Scyphiphora hydrophyllacea Gaertn. f. (Rubiaceae)

The sporogenesis and gametogenesis of Scyphiphora hydrophyllacea are described. The anther wall at the microspore mother cell stage consists of a persistent epidermis, ephemeral endothecium, a middle-layer and a glandular tapetum which remains uninucleate throughout. The pollen grain is binucleate when shed. The ovule is anatropous, unitegmic and tenuinucellar with a poorly developed nucellus consisting of a single layer of cells. The primary archesporial cell (occasionally two) divides once to form the megaspore and a micropylar cell which degenerates. The megaspore divides three times to form the eight-nucleate embryo sac of the Allium type.

Viral particles in developing pollen grains of Olea europaea

Double-walled tubules containing rows of isodiametric virus particles were observed in developing pollen grains of Olea europaea L. cultivar Correggiolo. Sometimes the tubules are contained in another double-walled tubular structure or in a tubular endoplasmic reticulum cistern. The viruses are present in the cytoplasm from the microspore mother cell stage up to the microspore stage but just before the first haploid mitosis they are to be found only in the pores, inside the evaginations formed by the plasmalemma. During the last phase of pollen grain development, after the germinative pores are completed, the viruses disappear.