Embryology of insects and myriapods; Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching embryologyofinse00joha Year: 1941 TRICHOPTERA AND LEPIDOPTERA 345 set free opposite the point of the stomodaeal invagination (Fig. 301). By the time the embryo is 52 hours old, the anterior cell mass has been forced away anteriorly and laterally from the apex of the invagination, and caudad of it the subesophageal body (Fig. 303B,suhoesh) is devel- oped. In the more generalized Orthoptera this body originates as a paire
Embryology of insects and myriapods; Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching embryologyofinse00joha Year: 1941 TRICHOPTERA AND LEPIDOPTERA 345 set free opposite the point of the stomodaeal invagination (Fig. 301). By the time the embryo is 52 hours old, the anterior cell mass has been forced away anteriorly and laterally from the apex of the invagination, and caudad of it the subesophageal body (Fig. 303B,suhoesh) is devel- oped. In the more generalized Orthoptera this body originates as a paired structure, but in Diacrisia it is vaguely bilobed. A B Fig. 303.—Diacrisia. Median longitudinal section of 52-hour embryo. A, procto- daeum (proct). B, cephalic end. (am) Amnion, {coel) Coelomic cavity, {stom) Stomo- daeum. (suboesb) Subesophageal body. The preoral region is lined with a single layer of cells. The tip of the stomodaeal invagination at 57 hours has become quite thin (Fig. 3045); the labrum (Ir) is well developed; and the neuroblasts (neur), char- acterized by their larger size, lie below an irregular layer of mesoderm in the cephahc lobes. At 59 to 60 hours the coelomic sacs, though quite small, have reached their fullest development in head segments four to
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