THE UNIVERSITY OF MANITOBA STUDIES ON OVINE PLACINTAL ...

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brith 13 minutes for hpl,. The second half-life of mpl,
is 36 hours as compared vrith 40 minutes for hpL (Friesen et
41, 1971). The estimated production rate of mpl, is 0.36
g/day, whlch is in contrast to 1.09 g,/day reported for
hPL. The placental concentration of mpt, (lrg,/g) 1\ret
weight) is 108 that of hpl, (Kaplan and crunbach, 1974).
SxperÍmen¡g of foetoectomy performed by Friesen
et a1 (197L) denonstrated that the foetus did not exert
any âcute control over mpL production, but, may influence
the rate of pl-acental growth and indirectly the productíon
of mPL. Like hPL, there is Virtuäl,ly no information on
the factors which reguJ.ate the synthesis and secretion
o f riPL.
(iv) ,
There is no information on the roles played
by mPL in the monkey during pregnancy. In limited
studies on the somatotropic activity of npl, (Shome and
Friesen. 1971) demonstrated that mpl. appears to have
a greater somatotropic activity than hpr. others (Josimovichet al ,
1964 ) found that mpl, has a bioLogic potency of the same
order of nagnitude as hpl, in the mouse vaginal mucification
luteotropic assay.