Development of microsporangia and microspores in Azolla filiculoides [China]
1987
He Guo-Fan | Lin Yue-Chan (Zhongshan Univ., Guangzhou (China). Dept. of Biology)
This paper presents a detailed report on the developmental processes of the microsporangium and its microspores in Azolla filiculoides Lam. Scanning electron photographs show the morphological structures of the respective developmental stages. The entire developmental process may be divided into six stages: (1) microspore mother cell initiating stage: the microsporangium initial on the placenta of the sporocarp gives rise to a sporogenous cell, and then divides 4 times to form 16 microspore mother cells; (2) Meiotic stage: meiosis takes place inside the callose walls of the microspore mother cells; (3) Microspores shrinking 1: after the callose walls of tetrads are dissolved, microspores released from the callose walls shrink intensely and then become spherical. (4) Microspore shrinking 2: the microspores give rise to the second contraction. (5) Massulae forming stage: the sporoplasmodium successively dissolves and the microsporangium divides into several large vesicles, each of which will form a massulae; and (6) Microspore germinating stage: each matured microspore inside the massulae gives rise to an androgonal initial, which divides twice to form four anthrerozoid mother cells. The relationship between the various morphological structures and their functions in the microsporangium developmental process are briefly discussed.
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