D E V E L O P M E N T S IN S E X U A L O R G A N O G E N E S I S
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differentiation of a male gonad. This fact recalls that observed in urodeles
during heterospecific, heterosexual parabiosis of diploid individuals, when
the male partner is of a small, slowly developing species.
On the whole, the haploid condition of a male limits its freemartin effect
of masculinization on a diploid female partner.
b. Diploid-Triploid Combinations. In heterosexual pairs (Fig. 16), the
male, whether Sn or 2n, always inhibits ovarian development in a 2n or
3n female (Gallien, unpublished).
FIG. 16. Pleurodeles adults (20 months) in parabiosis, d"3n X 9 2n combination. The
male completely inhibits the differentiation of the gonads of the female parabiont (arrows). This situation, in which the effect of the male predominates, occurs likewise in
d
71 2n X 9 3n combinations. Note the nuptial pads in the two parabionts.
4. Effects of Steroid Hormones on Sexual Differentiation and
Organogenesis in Amphibians
The parabiosis experiments in amphibians, which reproduced essentially
the freemartin effect in cattle, indicated that the chemical mediator responsible emanated from the embryonic gonads. Since in the adult the sex
hormones from the gonads are steroids, it was advisable to investigate, on
the one hand, the results when steroid hormones of the adult are introduced
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differentiation of a male gonad. This fact recalls that observed in urodeles
during heterospecific, heterosexual parabiosis of diploid individuals, when
the male partner is of a small, slowly developing species.
On the whole, the haploid condition of a male limits its freemartin effect
of masculinization on a diploid female partner.
b. Diploid-Triploid Combinations. In heterosexual pairs (Fig. 16), the
male, whether Sn or 2n, always inhibits ovarian development in a 2n or
3n female (Gallien, unpublished).
FIG. 16. Pleurodeles adults (20 months) in parabiosis, d"3n X 9 2n combination. The
male completely inhibits the differentiation of the gonads of the female parabiont (arrows). This situation, in which the effect of the male predominates, occurs likewise in
d
71 2n X 9 3n combinations. Note the nuptial pads in the two parabionts.
4. Effects of Steroid Hormones on Sexual Differentiation and
Organogenesis in Amphibians
The parabiosis experiments in amphibians, which reproduced essentially
the freemartin effect in cattle, indicated that the chemical mediator responsible emanated from the embryonic gonads. Since in the adult the sex
hormones from the gonads are steroids, it was advisable to investigate, on
the one hand, the results when steroid hormones of the adult are introduced