Pregnant uterus wall. Light micrograph of a section through the middle layer (myometrium) of the uterine wall of a healthy pregnant woman, showing the myometrial fibres. These fibres are greatly enlarged (hypertrohpy) compared to those of a non-pregnant woman. During pregnancy the number of cells within the uterus as a whole is increased by hyperplasia. See image BQ2607 for a similar image from a non-pregnant woman.