Question

A: Stratum basalis lines the uterine cavity and sloughs off during menstruation.
R: Straight arterioles supply blood to the stratum functionalis.

• A. Both A and R are correct and R is the correct explanation of A.
• B. Both A and R are correct but R is not the correct explanation of A.
• C. A is correct but R is incorrect.
• D. Both A and R are incorrect.

Answer 1

The correct option is D Both A and R are incorrect.

The endometrium is the innermost layer of the uterus where the developing zygote embeds itself for further growth and development. It has 2 layers- stratum functionalis and stratum basalis.

Stratum functionalis is the temporary layer. It lines the cavity of the uterus and is shed during menstruation. A new layer of stratum functionalis is made by the stratum basalis, which is a permanent layer.

The uterus is supplied blood by the uterine arteries which are branches of the internal iliac arteries. They branch off repeatedly while entering into the layers of the uterus. Just before the branches enter into the endometrium, they divide into 2 kinds of arterioles-
i. Straight arterioles- These supply the stratum basalis with the materials required for the regeneration of stratum functionalis.
ii. Spiral arterioles- These supply blood to the stratum functionalis.