THE UNIVERSITY OF MANITOBA STUDIES ON OVINE PLACINTAL ...

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(Mason et a1 , L973i Menon ¡ L974¡ Koch et al, 1974), in
agreenent r¡rith the generaL action of peptide hormones at the
cellular Ievel. The format.íon of cAMp is folJ-owed by
activat.ion of ovarian protein kinase (Vaf tukaiti s et al I LgTS)
and by phosphorylation of chromosmaL proteins in the immature
ovary (ilungmann et aL, !974).
ïn the case of the placenta, accelerat.ion of steroid
hydroxyration by hcc formed in the same celLs has been attributed
by Villee and Gabbe (1971) to an increase in NADpH availability
caused by the hormone.
B. HUMAN PI.ACENTAL LACTOGEN
i) Discovery of Human placêntal tactogen:
At the time that Íprolan,r or hCG came to
the attention of reproductive physiologists in 1930rs"
Madruzza in 1927 reported that vrhen placental homografts rrùere
implanted into virgin guinea pigs, lactation ensued.
These results suggested that the placenta contai.ns substances
other than gonadotropins. Subsequently, studies notabJ_y by
Ehrhart (1936), Fukushima (1961), Kurosaki (1961), described
the presence of a prolactin-Like and a gro$¡th hormone_like
substance in placental extracts. ft rdas not until 1962, when
,fosimovich and MacLaren published their paper on human
placental lactogen, also known as human chorionic sornmato-
mammotropin (hCS), that there was renewed interest in the
placenta as an endocrine organ. The discovery of hpl, by
Josimovich et a1 was based on the finding that hurnan