Dynamic of polysaccharide and lipid in the developing microsporangiums of Chinese fir (Cunninghamia lanceolata)

Microsporongium development in Chinese fir (Cunninghamia lanceolata) was investigated using cytochemical methods with a special attention to the fluctuations (in amount and distribution) of polysaccharide and lipid reserves along the development of the microsporangium. Semi-thin sections of microsporangia at different developmental stages were stained with periodic acid–Schiff (PAS) reagent and Sudan Black B to detect insoluble polysaccharides and neutral lipids, respectively. In young microsporangia, microspore mother cells began to accumulate starch grains and lipids, which disappeared during microspore development. Following microspore division, the starch grains present in bicellular pollen disappeared and abundant lipid deposits were accumulated. In mature pollen, only abundant lipids accumulated as storage material. The pollen wall of C. lanceolata is predominantly composed of polysaccharidic intine, and the sporopollenin-containing exine is weakly developed and only forms a thin layer covering the intine.