Final answer:
The endometrium is the uterine wall layer that includes the basal layer, known as the stratum basalis, which is important for regenerating the endometrium after menstruation.
Step-by-step explanation:
The portion of the uterine wall that includes the basal layer is the Endometrium. The endometrium is the innermost layer of the uterine wall, which contains a connective tissue lining known as the lamina propria. This layer is further divided into two layers: the stratum basalis and the stratum functionalis. The stratum basalis, which lies adjacent to the myometrium, does not shed during menstruation and is responsible for regenerating the stratum functionalis after each menstrual cycle. Thus, it is the Endometrium that contains the basal layer.