298
L. G A L L I E N
male intersexual gonad does not develop primary follicles, and regresses
rapidly, while the ovarian cortex of the genetic female differentiates normally. If the cortex of an intersexual gonad (ZZ) is associated with the
medulla from a female embryo (ZW), the presence of this medulla does not
prevent regression of the cortex.
Finally, if the cortex of a genetic female (ZW), removed at the age of
5-10 days (the period of sexual differentiation), is grafted into the coelom
and grown for 35-60 days by several transfers into a series of hosts, the
cortical tissue develops into a normal ovary. Under the same experimental
conditions, a cortex of ZZ constitution taken from an intersexual gonad
behaves differently. After the first transfer the oogonia do not continue to
differentiate. They degenerate in the course of the second and third transfers. Thus formation of primary follicles seems to be an intrinsic expression
of the genetic nature of the ovarian cortex.
Altogether, the facts presented concerning amphibians and birds demonstrate that the genetic control of sexual differentiation of the gonads is
permanent. It continues to be able to exercise its effects during the life of
the individual, although for a time epigenetic effects may be able to dominate, partially or completely, the genetic reactions that control sexual
differentiation.
These facts are important to consider, since they pose the problem of
hormonal effects, even at the genie level.
C. Sexual Organogenesis in Birds
In 1935, three groups of authors demonstrated the ability of steroid
hormones to induce a considerable degree of intersexuality in the sexual
differentiation of the gonads of the chick (Willier et al., 1935; Dantchakoff,
1935; Wolff and Ginglinger, 1935). Estrogens in particular feminize male
gonads. Recently, Haffen (1965) has stimulated marked feminization of
the gonads of genetic males of the quail (Coturnix coturnix) by treating
the embryos on the fourth day of incubation with the feminizing hormone,
diethylstilbestrol. The gonia become oocytes and commence yolk formation.
Certain ova are shed and pass into the oviduct. In the course of the studies
carried out since the initial research, two principal methods have been
employed: the culture of gonads and reproductive tracts in vitro, and
attempts to identify the steroid hormones from the embryonic gonads.
Before considering an analysis of these studies, it is appropriate to review
a few of the results obtained previously. Wolff (1946), grafting testes and
ovaries of 6-11-day-old chick embryos to young embryos of both sexes,
has shown that these gonads produce the same effect as androgenic and
estrogenic hormones. In particular, a young ovary has marked feminizing
effect on a male embryo, resulting in gonads with the appearance of ovotestes. Later Wolff and Wolff (1951), after destruction by x-rays of the
L. G A L L I E N
male intersexual gonad does not develop primary follicles, and regresses
rapidly, while the ovarian cortex of the genetic female differentiates normally. If the cortex of an intersexual gonad (ZZ) is associated with the
medulla from a female embryo (ZW), the presence of this medulla does not
prevent regression of the cortex.
Finally, if the cortex of a genetic female (ZW), removed at the age of
5-10 days (the period of sexual differentiation), is grafted into the coelom
and grown for 35-60 days by several transfers into a series of hosts, the
cortical tissue develops into a normal ovary. Under the same experimental
conditions, a cortex of ZZ constitution taken from an intersexual gonad
behaves differently. After the first transfer the oogonia do not continue to
differentiate. They degenerate in the course of the second and third transfers. Thus formation of primary follicles seems to be an intrinsic expression
of the genetic nature of the ovarian cortex.
Altogether, the facts presented concerning amphibians and birds demonstrate that the genetic control of sexual differentiation of the gonads is
permanent. It continues to be able to exercise its effects during the life of
the individual, although for a time epigenetic effects may be able to dominate, partially or completely, the genetic reactions that control sexual
differentiation.
These facts are important to consider, since they pose the problem of
hormonal effects, even at the genie level.
C. Sexual Organogenesis in Birds
In 1935, three groups of authors demonstrated the ability of steroid
hormones to induce a considerable degree of intersexuality in the sexual
differentiation of the gonads of the chick (Willier et al., 1935; Dantchakoff,
1935; Wolff and Ginglinger, 1935). Estrogens in particular feminize male
gonads. Recently, Haffen (1965) has stimulated marked feminization of
the gonads of genetic males of the quail (Coturnix coturnix) by treating
the embryos on the fourth day of incubation with the feminizing hormone,
diethylstilbestrol. The gonia become oocytes and commence yolk formation.
Certain ova are shed and pass into the oviduct. In the course of the studies
carried out since the initial research, two principal methods have been
employed: the culture of gonads and reproductive tracts in vitro, and
attempts to identify the steroid hormones from the embryonic gonads.
Before considering an analysis of these studies, it is appropriate to review
a few of the results obtained previously. Wolff (1946), grafting testes and
ovaries of 6-11-day-old chick embryos to young embryos of both sexes,
has shown that these gonads produce the same effect as androgenic and
estrogenic hormones. In particular, a young ovary has marked feminizing
effect on a male embryo, resulting in gonads with the appearance of ovotestes. Later Wolff and Wolff (1951), after destruction by x-rays of the