Define Oxytocin Hormone - Posterior Pituitary

Oxytocin is a polypeptide containing 9 amino acids. An 'oxytoxic' agent is a substance that causes the gravid uterus (uterus of a pregnant female) to contract and this is one of the primary effects of oxytocin. Oxytocin is secreted in moderate quantities during the latter part of the pregnancy and at the time of parturition (delivery).

It promotes contraction of the uterine muscles and aids in the expulsion of the body (process of parturition or labor). Oxytocin also causes myoepithelial cells of the mammary gland to contract, therefore, squeezing the milk from the alveoli into the ducts so that the baby can suck it during breastfeeding.