“…It has been confirmed that the inactivation is enzymic in nature. Various lines of evidence indicate that the syncytiotrophoblast is the site of placental oxytocinase (Page, 1946;Semm & Waidl, 1962;James, 1966;Seelig & Roemheld, 1969;Small & Watkins, 1975). Oxytocinase hydrolyses the peptide bond between N-terminal cystine and adjacent tyrosine, resulting in the loss of the biological effect of oxytocin.…”