Uterine gland. Coloured scanning electron micrograph (SEM) of a secretion (white/grey) coming from a uterine gland. This tubular gland is in the mucosa or endometrium (purple) that lines the uterus. The uterus is the organ in which the foetus develops. During the secretory phase of the menstrual cycle, following ovulation, the gland secretes glycogen. This provides the fertilized egg (ovum) with energy until it has developed a vascular link with its mother. Magnification unknown.