Abstract: The contractiaction of the protoplasts during the early development of the microsporangium os observed and the callose wall is fprmed at the same time.The microspor mother cells are separated from each other and were surrounded by callose wall before meiosis.The small pore about 0.2 to 0.3micron in diameter wihin the callose wall was observed.After the tetrad was formed,the nuclear evelope and the golgi bodies show a particular activity which is provably related to the exine depositing.

Key words: Pinus yunnansis