Observation on the formation and structural development of secretory cavities in integument of Ginkgo biloba L.

The development,accmulation of secretory products and the ultrastructure of secretory cells in integument of Ginkgo biloba L.were studied with light and electron microscopes.The results indicated that: ① The secretory structures in developmental prophase of integument,which were mainly distributing through several epidermal cells,consisted of secretory cavity and the initial cell cluster of secretory cavity;② The formation pattern of the secretory cavities was schizo-lysigeneous,with five developmental periods of the initial secretory cells,cells vacuolated,small spaces appeared between the cells,secretory cells dissolved,and secretory cells matured;③ The secretory cavities were formed in the external integument.The number and volume of secretory cavities increased gradually,and produced mass secreted substances in 10-30 days after pollination,Subsequently,the secretory cavity gradually lost secretion function with the development of episperm;④ The secretory cell walls showed in part ingrowth,and secreted substances produced by secretory cells seemed to be discharged from pit field to cavity.