How many abdominal sclerites would be there in a cockroach? Every tegmina of a cockroach has sclerites which are analogous to the bones of humans. Every abdominal segment of cockroach consists of two lateral sclerite plates called pleura along with a dorsal terga and a ventral sterna. But what will be the case with the last body segment where 10th sternum is absent? I mean will, there be any pleuron in the tenth segment because, following our textbook, pleura serve for articulation among sterna and terga and also spiracles are present in the first eight abdominal segments but the 10th sternum is absent in _Periplaneta americana_. Actually there is no evidence of the presence of any pleurons in the last segment in our text book. Moreover, there are no abdominal spiracles in the 9th and 10th segments so there is no particular reason to say that pleura are present in the 9th and 10th segments as well.

## Tergal plates:

There are ten tergal plates. The $8^{th}$ tergum in the male and both $8^{th}$ and $9^{th}$ terga in the female are not visible as they are overlapped by the $7^{th}$ tergum.

**The $10^{th}$ tergum extends beyond the posterior end of the body and has a deep groove in the middle of its free end.**

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## Sternal plates:

Only nine sterna are present as the $10^{th}$ sternum is absent. In the male, nine sterna are visible whereas in the female, only seven sterna are visible.

In females, the $7^{th}$, $8^{th}$ and $9^{th}$ sterna together forma brood pouch. The brood pouch has two parts: the anterior – genital chamber or gynatrium and the posterior – gothecal chamber.

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(source: lander.edu)

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(source: lander.edu)

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(source: biologydiscussion.com)

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Sources:

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## Update:

Youtube links for Cockroach dissection:

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