Cervical lining. Coloured scanning electron micrograph SEM of a fold in a cervical mucous membrane. The cervix is the canal that links the uterus womb to the vagina. The mucous membrane consists of mucus_secreting cells. Folds, known as plicae palmatae, in the mucous membrane increase the surface area for the secretion of mucus. Mucus is secreted in response to the female sex hormone oestrogen. Maximal secretion is during ovulation, when the mucus is most hydrated, to ease the movement of sperm.