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 OBTHOPTEROIDEA {PANORTHOPTERA) 233 medially, the median extension forming the ventral diaphragm. In the 94-hour stage a deep furrow develops in the lateral coelomic wall at the junction of the dorsorostral with the ventral pouch (Fig. 156), which deepens and eventually separates the dorsal from the ventral coelom. The ventral coelom gives rise to the leg musculature. At the same time, t
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 OBTHOPTEROIDEA {PANORTHOPTERA) 233 medially, the median extension forming the ventral diaphragm. In the 94-hour stage a deep furrow develops in the lateral coelomic wall at the junction of the dorsorostral with the ventral pouch (Fig. 156), which deepens and eventually separates the dorsal from the ventral coelom. The ventral coelom gives rise to the leg musculature. At the same time, the dorsal coelomic portion (both rostral and anal) is divided by a horizontal partition into upper (dorsal) and lower (ventral) halves. Soon the intersegmental partitions between the upper portions of the dorsal pouches of the coelomic sacs disappear, with the result that there are formed two continuous lateral tubes extending from the first thoracic to the ninth abdominal segment. The somatic mesoderm thickens and forms the so-called 'myoblast plate' whose dorsal edge contains cardioblasts (compare Fig. 160). The central part becomes fatty tissue except the uppermost end which forms for a time the wall Fig. 156.—LocMsia. Cross section of distal and of second thoracic segment showing ventrolateral furrow in coelomic wall, {am) Amnion, {coel) (1) Dorsorostral, (3) ventral pouch of coelomic sac. {dc) Provisional dorsal closure, {eel) Ectoderm, {mes) Median mesoderm, {sin) First lateral blood sinus. of the middorsal blood sinus. After completion of the heart it gives out cells that form the pericardial cells. The upper portion of the myoblast plate forms the dorsal suspensory muscles of the heart; the inner layer, the pericardial septum. The median walls of the upper portion of the dorsal pouch form fatty tissue in the thorax and in the first, eighth, and ninth abdominal segments. In the second to tenth abdominal segments it forms the gonads as well. As for the lower p
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