THE UNIVERSITY OF MANITOBA STUDIES ON OVINE PLACINTAL ...

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(ii) Chenistry and CeLl;oTigin of -¡n!lc:
At Èhe present, the amino acid composition and
primary amino acid sequence of nCG are not. kno!ùn.
uslng immunofluorescent staining techniques,
the mCc was locaLized in the syncytiotrophoblast (pierce
et al-, 1964; Luckett, 1970).
(iii) Inununological Properties of rnCG:
Antibodies generated against. hCG in rabbits have
been used to examine ant,igenic similarit.ies among primate
chorionic gonadotropins from serum or urine (Tuller et al,
1969; Nixon et al, I97I) . Recent studies by Chen et al
(1976) demonstrated that vrhen choríonic gonadotropitis
from human (hCG), chimpanzee (chCG) , goril-la (gCG),
organgutan (orCG), baboon (bCG), macaque (mcc) and
marmoset (nacc) lvere invesÈigated in a radioimmunoassay
system using an antíserum with antigenic determinants known
to reside in the terminal 15 amino acid residues of the
unique carboxyl-terminal peptide of hcc-beta lrithout
cross-reactivity to htH, there is cLosê antigenic sirnilarity
anong hCG, chCG and gCG but minimal similarity with other
simian CG's.
(iv) Physiological Role of mCG During pregnancy!
In a series of experiments in which hCG was
ad¡ninistered inËo the rhesus monkeys during the luteal
phase, the length of, the menstrual cycle was significantly
prolonged ( Hisaw, 1944') . l¡'lhen he compared the period