Contractile responses of the myoepithelial cells of the mouse mammary gland in situ

In experiments on laboratory mice in situ, a contractile response of the mammary gland's myoepithelial cells was electromechanically studied. A gradual response to oxytocin application, with a relatively fast front of contraction and a prolonged relaxation period, was recorded. The contraction time up to the maximum was 8.5 s, the relaxation period--31 s. In many experiments (73%), following a single oxytocin application, a few successive contractions of the alveola were registered. The high velocity of the myoepithelium contraction maintains a necessary pressure for fast transport of the secret within the ducts. The contraction low velocity as well as appearance of new myoepithelium contraction waves creates conditions for keeping the secret within the ducts, extending the time when the litter can receive the feeding.