D E V E L O P M E N T S I N SEXUAL O R G A N O G E N E S I S
287
in the course of sexual differentiation, and on the other hand, the detection
of these same hormones in the embryonic gonads. The effects of steroids
were initially tested in the chick, to be considered later (Dantchakoff,
1935; Willier et al, 1935, 1937; Wolff and Ginglinger, 1935). However, it
is in the amphibians that the most striking analysis of these problems has
been possible.
The mass of results obtained at first appears to be very complex. As a
matter of fact, after a comparative study they may be understood if the
following factors are kept in mind :
(A) The variable degree of the effect of genetic factors controlling sexual
differentiation according to species; a species with labile determination in
which the factors for maleness (M) and femaleness (F) are near equilibrium
will react readily to interference from the outside.
(B) The permanence of the genetic system throughout life. It can be
temporarily dominated by exogenous interference during a specific phase of
development, usually during differentiation. Later, however, the deviation
that was obtained is terminated because the genie system, always active,
finally imposes its control, if the reactive areas (cortex or medulla) had not
been completely destroyed at the time of the original change.
(C) The interference by an external factor must be considered as that of a
teratogenic agent. Actually, the doses of steroid hormones used are often
above physiological levels. This is shown by the reaction of the primordia
themselves before their differentiation. They affect various somatic organs
not directly related to sex, the skeleton, for example (Collenot, 1965).
(D) The gonadal primordium in vertebrates is composed of two regions,
a cortex with gynogenic prospective potency and a medulla which is androgenic. The effect seen after treatment is the result of competition between
these two areas. Thus any interference affecting one of these areas in
particular results in stimulating the development of the opposite area.
Consequently, differential inhibitory effects are produced that can lead to
intersexuality or even to a reversal of sexual differentiation. This mechanism has been designated as a "paradoxical effect" (Padoa, 1936; Gallien,
1940, 1941, 1944, 1954, 1955b, 1956).
In order to elucidate the results already obtained, those will be considered first that have been analyzed after the administration of the two
groups of steroid hormones studied most extensively: estrone-estradiol
(gynogenic) and testosterone-methyl testosterone (androgenic). These
results are set forth in Table II (reviewed in Gallien, 1959, 1960, 1962a;
Collenot, 1965).
From all of these results, the following three groups can be set up relative
to the sexual differentiation of the gonads (Gallien, 1960, 1962a).
a. Group I: Total, Permanent, and in the Best Cases, Functional Reversal
of the Gonads. (i) Androgenic steroids. Total masculinization occurs in
287
in the course of sexual differentiation, and on the other hand, the detection
of these same hormones in the embryonic gonads. The effects of steroids
were initially tested in the chick, to be considered later (Dantchakoff,
1935; Willier et al, 1935, 1937; Wolff and Ginglinger, 1935). However, it
is in the amphibians that the most striking analysis of these problems has
been possible.
The mass of results obtained at first appears to be very complex. As a
matter of fact, after a comparative study they may be understood if the
following factors are kept in mind :
(A) The variable degree of the effect of genetic factors controlling sexual
differentiation according to species; a species with labile determination in
which the factors for maleness (M) and femaleness (F) are near equilibrium
will react readily to interference from the outside.
(B) The permanence of the genetic system throughout life. It can be
temporarily dominated by exogenous interference during a specific phase of
development, usually during differentiation. Later, however, the deviation
that was obtained is terminated because the genie system, always active,
finally imposes its control, if the reactive areas (cortex or medulla) had not
been completely destroyed at the time of the original change.
(C) The interference by an external factor must be considered as that of a
teratogenic agent. Actually, the doses of steroid hormones used are often
above physiological levels. This is shown by the reaction of the primordia
themselves before their differentiation. They affect various somatic organs
not directly related to sex, the skeleton, for example (Collenot, 1965).
(D) The gonadal primordium in vertebrates is composed of two regions,
a cortex with gynogenic prospective potency and a medulla which is androgenic. The effect seen after treatment is the result of competition between
these two areas. Thus any interference affecting one of these areas in
particular results in stimulating the development of the opposite area.
Consequently, differential inhibitory effects are produced that can lead to
intersexuality or even to a reversal of sexual differentiation. This mechanism has been designated as a "paradoxical effect" (Padoa, 1936; Gallien,
1940, 1941, 1944, 1954, 1955b, 1956).
In order to elucidate the results already obtained, those will be considered first that have been analyzed after the administration of the two
groups of steroid hormones studied most extensively: estrone-estradiol
(gynogenic) and testosterone-methyl testosterone (androgenic). These
results are set forth in Table II (reviewed in Gallien, 1959, 1960, 1962a;
Collenot, 1965).
From all of these results, the following three groups can be set up relative
to the sexual differentiation of the gonads (Gallien, 1960, 1962a).
a. Group I: Total, Permanent, and in the Best Cases, Functional Reversal
of the Gonads. (i) Androgenic steroids. Total masculinization occurs in