Which layer of uterine tissue reacts to hormonal changes during the menstrual cycle?

The endometrium is the layer of the uterine tissue that responds to hormonal changes during the menstrual cycle. This inner lining thickens in preparation for a potential implantation of a fertilized egg, influenced predominantly by estrogen and progesterone. If fertilization does not occur, the hormone levels drop, leading to the shedding of the endometrium during menstruation. This cyclical response is essential for reproduction, as it creates the optimal environment for embryo implantation if conception takes place.

In contrast, the perimetrium serves as a protective outer coating of the uterus and does not engage in the hormonal responses related to the menstrual cycle. The myometrium, consisting of smooth muscle, is responsible for uterine contractions but also does not directly respond to hormonal changes. The exometrium is not a recognized layer of uterine tissue in this context. Thus, the endometrium's unique role in reacting to hormonal fluctuations makes it the correct answer.