The placenta, which produces many hormones,
is not known to produce oxytocin. This
hormone is produced in the posterior pituitary
and primarily responsible for uterine contraction claimed that she uses powdered dried sheep placenta,
administered orally, to facilitate delivery in
patients with uterine inertia.
Sisson et al. (1961) have shown that dialysates
from homogenates of rabbit placenta contain a
hypotensive-inducing, smooth muscle contracting
principle, which was later shown by Sisson (1963)
to be a polypeptide which was not oxytocin or
bradykinin. The substance, however, did not contract
the gravid rabbit uterus.