THE UNIVERSITY OF MANITOBA STUDIES ON OVINE PLACINTAL ...

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(iv¡ Other .Sêcretêd ptacentäI protêins:
There are reports of other peptide hormones made in
the human placenta. A nu͡be r of authors have described
melanocyte-stimulating activity, and others report the
presence of oxytocin, vasopressin, relaxin and renin. None
of these has reached the poínt of purification and rigorous
identification. A ner,ù hormonal activity, uterotropic
placental hormone (UTPH) has been reported (Beas et al,
1975) in which a partially purified placental protein has
been found to cause grorrth of mouse uteri " This protein
has been detected in the blood of pregnant, but not of
nonpregnant, fromen.
A number of plasma proteíns of no known function
have also been identfied in serum of pregnant women and
have been especial-ly studied by Bohn (I974a, b) anil by
Lin et aL (L974, 1976a, b). The latter correlate their
nomenclature for these pregnancy-associated proteins
(PAPPS) with some of the pregnancy proteins of Bohn and
other investigators : PApp-A, pApp-B, and pApp-C (siniLar
to Bohnrs SP1) appear to be synthesized by the placenta,
s ince they are absent f rom the plasma of nonpregnant ,¿ql'';iriT 1:'=:*., .
¡Ld: 'r:- ": : j'r'ì':
women and increase in amount during the second fraff od ...-...-.- t\,
-- -q ' ': '.- t
gestation, though at díf ferent rates (Iin et al, 19 74 )\:._..- . - '.'".--'. .:d'
--. . . . i. r ; { .:
; . . : ... -
The PAPPs also disappear from the plasma '*:å:eo'4t''r: after delivery,
$rith hal-f-Life varying from I-4 days. Finally, fluorescent
antibodies to PAPP-A and pApp-C reveal that these proteins
are present in abundance in term placentas, notably in the