Uterus lining. Light micrograph of a cross section through the uterus lining (endometrium) at late secretory phase of a woman's menstrual cycle. The stratum basalis layer (bottom, pink) undergoes little change during the cycle. Above this layer is the stratum spongiosum (purple). This layer is characterized by the saw-tooth appearance of glands containing thick, glycogen-rich secretions. Above this layer (top, light purple) is the stratum compactum. The spongiosum and compactum layers are shed during menstruation. Menstruation marks the end of the cycle's secretory phase which began at ovulation. Haematoxylin and eosin stained. Magnification x6 at 35mm size.