CUTICLE FORMATION DURING THE EMBRYONIC-DEVELOPMENT OF THE DIPTERAN CERATITIS-CAPITATA WIED

Two cuticles are secreted at different times over the epidermal cells during the embryonic development of Ceratitis capitata. The first cuticle, 12-14 nm thick, appears in 12-13 hr old embryos at the beginning of gastrulation when the posterior midgut invagination occurs. This cuticle corresponds to the embryonic envelope or atypical cuticle of previous authors. The second cuticle, which becomes the first larval cuticle, appears 38-40 hr after egg deposition. The first phase of larval cuticle secretion occurs when morphogenetic movements cease. This cuticle consists of three layers: cuticulin, epicuticle and endocuticle. Freeze-fracture replicas show intramembrane clusters of particle associated with the P-face of the membrane in correspondence with the short protuberances of the epidermal cell apex.