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 stom eci—. A B C Fig. 166.—Locusta. Sagittal sections. A, stomodaeum of 52-hour embryo. 5, stomodaeum of 56-hour embryo. C, proctodaeum of 70-hour embryo, {am) Amnion. (ec<) Ectoderm, {lb) Labium. {Ir) Labrum. {md) Mandible, (mes) Mesoderm, {mx) Maxilla, {prod) Proctodaeum. {stom) Stomodaeum. then by the splanchnic mesoderm which grows around the yolk outside the provisional dorsa
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 stom eci—. A B C Fig. 166.—Locusta. Sagittal sections. A, stomodaeum of 52-hour embryo. 5, stomodaeum of 56-hour embryo. C, proctodaeum of 70-hour embryo, {am) Amnion. (ec<) Ectoderm, {lb) Labium. {Ir) Labrum. {md) Mandible, (mes) Mesoderm, {mx) Maxilla, {prod) Proctodaeum. {stom) Stomodaeum. then by the splanchnic mesoderm which grows around the yolk outside the provisional dorsal closure, thus cutting off the little that remains of the extraembryonic yolk. The provisional dorsal closure then degener- ates, leaving the thin splanchnic mesoderm as the second provisional mid-gut cover until four days after blastokinesis. One day later (two days before hatching) the cell masses at the blind ends of the stomo- daeum and proctodaeum quickly spread over the entire yolk to form the definitive mid-gut epithelium. At the same time, the stomodaeal and proctodaeal membranes rupture, thus connecting the lumen of the mid- gut with those of the fore- and hind-guts. In the 56-hour-old embryo the dorsal walls of the mandibular coelom (Fig. 153) give out large, rounded, loosely arranged cells which spread mediodorsally and soon form an arched structure, the subesophageal body. It ultimately comes to lie beneath the stomodaeum, losing its connections with the coelomic walls. The cells of the subesophageal body reach a
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