Uterus endometrium. Coloured Scanning Electron Micrograph (SEM) of a section through the inner wall (endometrium) of the human uterus. At top is the surface of the endometrium containing openings to tubular uterine glands. Beneath the epithelium are seen the tubular bodies of uterine glands.The glands are embedded in abundant collagen and reticular fibres of stroma connective tissue. After ovulation the glands become active and secrete substances to nourish the fertilised egg. Magnification: x400 when printed at 10 cm wide.