The sporal external shape and ultrastructure of eight kinds of microsporidias collected from different sources which are pathogenic to silkworm were observed and compared under light microscope and electronic microscope.The results are (1) No specific characterestics were found on the sporal external shape among these microsporidias.(2)There are resemblances among these microsporidias in ultrastructure,such as layers of sporal wall,structure of pola...