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
289
Ranidae and Hylidae (anurans); 100% males are obtained (Gallien, 1937).
Genetic proof of sex reversal is furnished by the study of the offspring of a
crossing in Rana japonica (Kawamura and Yokota, 1959).
Neomale X normal female — ► 100% 9
( 9 - < f )
Genetic constitution: XX -► XX
XX
-> 100% XX ( 9 )
(it) Gynogenic steroids. Total feminization occurs in lower anurans
(Xenopus laevis) and urodeles (Ambystoma, Hynobius, Triturus helveticus,
Pleurodeles); 100% females are obtained (Fig. 17C). Genetic proof of sex
reversal is furnished by the study of the offspring of crossing:
Neofemale X normal male —* 100% cf
(cf-> 9)
Genetic constitution:
ZZ -» ZZ
ZZ
-> 100% ZZ ( Crosses have been verified in P. waltlii (Gallien, 1954), X. laevis (Gallien,
1955a, 1956; Chang and Witschi, 1955). They indicate that in these species
the male sex is homogametic. This conclusion confirms those of Humphrey
(1945, 1948, 1957) on Ambystoma and of Mikamo and Witschi (1963, 1964)
on Xenopus.
b. Group II: Partial Reversal (Temporary Intersexuality or No Effect).
(i) Androgenic steroids. Sexual differentiation of genetic males and females
is not perceptibly altered. The sex ratio remains 50% cfcf :50% Ç 9 \Pelobates cultripes, Pelodytes punctatus, Bufo bufo, Discoglossus pictus, Alytes
obstetricans, Bombina variegata (Gallien, 1958, 1959; Collenot, 1965). In
other words, the genetic determination in the female is such that the male
hormone can not superimpose its effect on the genetic control. Testes differentiate in genetic males (Fig. 18B).
(ii) Gynogenic steroids. They exert a varying degree of feminizing influence on genetic males. The effect is usually temporary. Ovaries differentiate in genetic females (Fig. 18). In decreasing order of positive
reaction (feminization) the species tested are arranged as follows:
Pelobates cultripes: feminization complete but temporary.
Pelodytes punctatus: partial feminization—intersexuality (Figs. 18E and
F).
Triturus alpestris: partial feminization—temporary intersexuality.
Discoglossus, Alytes, Bufo: partial feminization, weak and temporary.
Bombina variegata: no reaction—genetic males form testes (Figs. 18A and
B).
The species in group II are linked to those in group I by their type of
reaction; the effects of the steroids are qualitatively of the same nature in
the two groups, sometimes strong (Pelobates), but more often weak, and
ultimately absent (Bombina). Thus the sexualizing effects of the sex steroids
289
Ranidae and Hylidae (anurans); 100% males are obtained (Gallien, 1937).
Genetic proof of sex reversal is furnished by the study of the offspring of a
crossing in Rana japonica (Kawamura and Yokota, 1959).
Neomale X normal female — ► 100% 9
( 9 - < f )
Genetic constitution: XX -► XX
XX
-> 100% XX ( 9 )
(it) Gynogenic steroids. Total feminization occurs in lower anurans
(Xenopus laevis) and urodeles (Ambystoma, Hynobius, Triturus helveticus,
Pleurodeles); 100% females are obtained (Fig. 17C). Genetic proof of sex
reversal is furnished by the study of the offspring of crossing:
Neofemale X normal male —* 100% cf
(cf-> 9)
Genetic constitution:
ZZ -» ZZ
ZZ
-> 100% ZZ ( Crosses have been verified in P. waltlii (Gallien, 1954), X. laevis (Gallien,
1955a, 1956; Chang and Witschi, 1955). They indicate that in these species
the male sex is homogametic. This conclusion confirms those of Humphrey
(1945, 1948, 1957) on Ambystoma and of Mikamo and Witschi (1963, 1964)
on Xenopus.
b. Group II: Partial Reversal (Temporary Intersexuality or No Effect).
(i) Androgenic steroids. Sexual differentiation of genetic males and females
is not perceptibly altered. The sex ratio remains 50% cfcf :50% Ç 9 \Pelobates cultripes, Pelodytes punctatus, Bufo bufo, Discoglossus pictus, Alytes
obstetricans, Bombina variegata (Gallien, 1958, 1959; Collenot, 1965). In
other words, the genetic determination in the female is such that the male
hormone can not superimpose its effect on the genetic control. Testes differentiate in genetic males (Fig. 18B).
(ii) Gynogenic steroids. They exert a varying degree of feminizing influence on genetic males. The effect is usually temporary. Ovaries differentiate in genetic females (Fig. 18). In decreasing order of positive
reaction (feminization) the species tested are arranged as follows:
Pelobates cultripes: feminization complete but temporary.
Pelodytes punctatus: partial feminization—intersexuality (Figs. 18E and
F).
Triturus alpestris: partial feminization—temporary intersexuality.
Discoglossus, Alytes, Bufo: partial feminization, weak and temporary.
Bombina variegata: no reaction—genetic males form testes (Figs. 18A and
B).
The species in group II are linked to those in group I by their type of
reaction; the effects of the steroids are qualitatively of the same nature in
the two groups, sometimes strong (Pelobates), but more often weak, and
ultimately absent (Bombina). Thus the sexualizing effects of the sex steroids