Abstract: 【Aim】 The aim of this study is to optimize the paraffin section technology and to examine the developmental pattern of serosal cuticle in the early embryonic stage of Locusta migratoria. 【Methods】 The paraffin section technology for L. migratoria embryo was modified on the steps of fixation, washing, dehydration and clearing. The developmental process of serosal cuticle was analyzed with hematoxylin-eosin staining (HE staining) and fluorescent staining following paraffin section of day 3-10 embryos of L. migratoria. The katatrepsis of embryo from micropyle to tail was observed by HE staining of the paraffin sections of L. migratoria from day 6-8 embryos, which were cut longitudinally. 【Results】 The optimized paraffin section steps for L. migratoria embryo included: pretreating the egg with NaClO and punching it before fixation, then washing, dehydrating and clearing the fixed egg for 30 min, respectively. Integrative and clear sections of the whole epidermis structure of the embryonic stage were obtained by using our optimized paraffin section technology. The serosal cuticle formation and chitin deposition were completed on day 5 and began to degrade on day 8 during the embryonic stages at 30℃. The katatrepsis occurred from day 6 to day 7 in the embryonic stages, accompanied by the morphological change of serosa and serosal cuticle. 【Conclusion】 We optimized the paraffin section technology for L. migratoria embryo, and revealed the developmental pattern of serosal cuticle and katatrepsis. This study lays a foundation for studying the metabolisms of embryonic development in L. migratoria.

Key words: Locusta migratoria, paraffin section modification, HE staining, embryo, serosal cuticle, katatrepsis