Describe the structure of oothecae in cockroach.

It is part of male cockroach

Figure given below shows reproductive system of female cockroach. The correct labellings indicated by alphabets $(A, B \& C)$ are respectively

Which of the following is the correct statement about the circulatory system of cockroach

....... is function of nephrocytes and urecose gland.

Tegmina in cockroach, arises from :