How is the brood pouch formed in a female cockroach? Name the parts present in it.

In female cockroach the sterna of the 8th and 9th abdominal segments in folds, resulting in the formation of a brood pouch. Brood pouch is a sac like cavity in the female cockroach in which in eggs and the embryos are developed. 

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There are ten abdominal segments in the adult but in the embryo it is eleven segmented.The tenth abdominal segment has no sternum .There is a pair of triangular, platelike structures at the posterior side of cockroach below the 10th tergum. They are called paraprocts.Anus lies between them.

Abdomen also bears eight pairs of spiracles .

A pair of fifteen segmented appendages called anal cerci arises from the junction between the 9th and 10th segments on the dorsal side on each side. They occur in both male and female cockroaches .

These anal cerci are regarded as the appendages of the vestigial eleventh segment.In the male cockroach a pair of unsegmented anal styles is attached , one on either side , to the 9th abdomianal sternum.

In the female the sterna of the 8th and 9th abdominal segments are infolded to form the genital pouch or brood pouch. The anterior part of the genital pouch is called gynatrium and the posterior part is called oothecal chamber .

Female bears three pairs of chitinous plates called gonapophyses. The 8th sternum bears one pair and the 9th sternum bears two pairs of gonapophyses.Gonapophyses of female cockroach serve in copulation , formation of ootheca and oviposition.The gonapophyses of the male are called phallomeres.These are formed from the 9th sternum.The male has three phallomeres on the ventral side.These are ventral , left and right phallomeres. The male genital aperture is present at the base of the ventral phallomere.The left phallomere bears a psudopenis , a titillator and an aspirate lobe.The right phallomere bears a hook and a serrate lobe . The gonapophyses of the male and female interlock with one another during copulation.

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