The formation of zona radiata in Pseudosciaena crocea revealed by light and transmission electron microscopy

► In this study, we investigate the formation of zona radiata, theca cell and granulosa cell in the teleost Pseudosctaena crocea. ► Four layers exist outside the oocyte plasamallea, i.e., theca cell layer, basal membrane, granulosa cell layer and zona radiata. ► Microvilli fully participates in the formation of zona radiata and granulosa cells. ► Three layers, Z1, Z2, and Z3 in the zona radiata are formed. The electron density is Z1 > Z2 > Z3. ► We conclude that the egg envelope of vertebrate eggs is homologous among teleosts.