Oxytocin

**Definition:** A nonapeptide hormone released from the neurohypophysis (PITUITARY GLAND, POSTERIOR). It differs from VASOPRESSIN by two amino acids at residues 3 and 8. Oxytocin acts on SMOOTH MUSCLE CELLS, such as causing UTERINE CONTRACTIONS and MILK EJECTION.

**Tree numbers:** - D06.472.699.631.692.433 - D12.644.548.691.692.433

**Synonyms:** - Ocytocin