Light Microscopic Observations on Pollen and Anther Development in Rice (Oryza sativa L.) : I. Stages from pollen mother cells to tetrads

Abstract

Development of pollen mother cells (PMCs) and the cells in anther wall tissues of rice plants was studied by the glycol methacrylate semithin method for light microscopy. During the early stage of PMC formation, four anther wall tissues-epidermis, endothecium, middle layer and tapetum were devoloped. By the release of PMC, hardenning and decrease in permeability were sugested to occur in the cell wall area between middle layer and tapetum. Tapetal cells often divided and became multinucleate. Microfibrillar substances, preserved well with aldehyde fixation, were observed in intracellular vesicles and the callose wall area of PMCs and in the anther sap. Nuclear structures of PMCs appeared rather more clearly by osmium postfixation. During the callose wall disorganization, the nuclear changes of PMCs in meiotic prophase were contirmed. After the release of PMCs, keeping the bordered position upon the tapetal layer, PMCs entered into the mataphase. Cellular contraction, occurred immediately before the first and second nuclear divisions, marked the initiation of karyokinesis. The directions of meiotic divisions to the long axis and to the tapetal inner surface were estimated and the close contact of the released PMCs and their daughter cells with the tapetal inner surface was comfirmed.