300
L. GALLIEN
ovotestis. Ovarian cortex develops, but the medulla persists. Thus the
medullary cords do not regress as they normally do. This form of intersexuality, which is not obtained by injection of steroid hormones, probably
expresses a hormonal disequilibrium linked to the conditions of the culture.
Culture in vitro makes possible in birds at the organ level the parabiosis
performed in amphibians between two embryos (Wolff and Haffen, 1952b).
Two undifferentiated left gonads taken from two different duck embryos
are placed together in culture. When the combination involves a gonad from
a genetic female and one from a genetic male, the latter is feminized,
transformed into an ovary or an ovotestis. This experiment confirms the
results obtained by grafting. Also, left gonads from genetic males may be
grown on a culture medium supplemented with estradiol. With droplets
of the oil solution of the hormone in contact with the explant, a cortical
fringe develops, and the gonad differentiates as an ovotestis.
Organ culture methods have been used to analyze the interactions between embryonic gonads when the two gonads are taken from different
classes of vertebrates. Weniger (1961) showed that in culture embryonic
testes of 12-17-day-old mice have a strong feminizing effect on the male
gonads of 5-day-old chick embryos with which they were associated.
Salzgeber (1963) removed the embryonic ovaries of mice between the
twelfth and twenty-first day of gestation and associated them in culture
with 6-10-day-old chick embryonic gonads. After 2-6 days in culture,
the expiants were grafted into the coelom of a young chick embryo where
they developed until autopsy, at the twelfth to nineteenth day. In the
association of mouse ovary and chick testis, the development of the mouse
ovary is inhibited. The effect is primarily on cortical structures; oocytes
degenerate or do not develop. Certain medullary structures persist, notably
the rete ovarii. Thus the male hormone secreted by the testis of the chick
has an inhibitory action on the ovary of the mouse. According to the author,
in the most striking cases this can be interpreted as masculinization.
This group of experiments, however interesting it may be, must be
interpreted with care, since a variety of factors are involved. Under conditions of culture and grafting, the participation of certain nutritive factors
that are difficult to analyze cannot be excluded. These facts appear to be
related, more or less, to the effects of intersexuality obtained by the action
of epigenetic factors that are traumatizing or teratogenic.
The culture technique makes it possible to analyze the physiological
conditions that control the disappearance of the Mullerian ducts in the male
(Wolff, 1953). The Mullerian ducts are present in both sexes before the
differentiation of the gonads. The left duct becomes the oviduct in the
female. In the male, after the ninth day of incubation, the epithelium of
the ducts begins to be necrotic, and by the thirteenth day, the ducts disappear. Mullerian ducts taken from female embryos at any stage survive
L. GALLIEN
ovotestis. Ovarian cortex develops, but the medulla persists. Thus the
medullary cords do not regress as they normally do. This form of intersexuality, which is not obtained by injection of steroid hormones, probably
expresses a hormonal disequilibrium linked to the conditions of the culture.
Culture in vitro makes possible in birds at the organ level the parabiosis
performed in amphibians between two embryos (Wolff and Haffen, 1952b).
Two undifferentiated left gonads taken from two different duck embryos
are placed together in culture. When the combination involves a gonad from
a genetic female and one from a genetic male, the latter is feminized,
transformed into an ovary or an ovotestis. This experiment confirms the
results obtained by grafting. Also, left gonads from genetic males may be
grown on a culture medium supplemented with estradiol. With droplets
of the oil solution of the hormone in contact with the explant, a cortical
fringe develops, and the gonad differentiates as an ovotestis.
Organ culture methods have been used to analyze the interactions between embryonic gonads when the two gonads are taken from different
classes of vertebrates. Weniger (1961) showed that in culture embryonic
testes of 12-17-day-old mice have a strong feminizing effect on the male
gonads of 5-day-old chick embryos with which they were associated.
Salzgeber (1963) removed the embryonic ovaries of mice between the
twelfth and twenty-first day of gestation and associated them in culture
with 6-10-day-old chick embryonic gonads. After 2-6 days in culture,
the expiants were grafted into the coelom of a young chick embryo where
they developed until autopsy, at the twelfth to nineteenth day. In the
association of mouse ovary and chick testis, the development of the mouse
ovary is inhibited. The effect is primarily on cortical structures; oocytes
degenerate or do not develop. Certain medullary structures persist, notably
the rete ovarii. Thus the male hormone secreted by the testis of the chick
has an inhibitory action on the ovary of the mouse. According to the author,
in the most striking cases this can be interpreted as masculinization.
This group of experiments, however interesting it may be, must be
interpreted with care, since a variety of factors are involved. Under conditions of culture and grafting, the participation of certain nutritive factors
that are difficult to analyze cannot be excluded. These facts appear to be
related, more or less, to the effects of intersexuality obtained by the action
of epigenetic factors that are traumatizing or teratogenic.
The culture technique makes it possible to analyze the physiological
conditions that control the disappearance of the Mullerian ducts in the male
(Wolff, 1953). The Mullerian ducts are present in both sexes before the
differentiation of the gonads. The left duct becomes the oviduct in the
female. In the male, after the ninth day of incubation, the epithelium of
the ducts begins to be necrotic, and by the thirteenth day, the ducts disappear. Mullerian ducts taken from female embryos at any stage survive