Question

if there is hymen in the vaginal passage then how the menstrual flow is possible

Answer 1

Hymen is actually not a whole membrane but a ring of mucosal tissue which guards the vaginal entry which only partially covers it. It is very thin and elastic in some women and thick in others , however it get perforated during the fetus stage. If it would  be covered , vaginal blood obviously would't get out and this case is known as Imperforate Hymen and can be treated by surgery.

Hope this helps you. This is an original answer.

Please mark as the brainliest:)