268
L. GALLIEN
ferentiation. These facts are in close approximation to those shown in
Bonellia, Crepidula, Ostrea, and Teredo. They lead in the direction of those
established in crustaceans, insects (lampyrids), and finally with certain
teleosts (Smaridae and Sparidae) and amphibians.
B. Endocrine Controls in Sexual Differentiation in Insects:
Apical Androgenic Tissue
For some time sexual differentiation in insects has seemed to be an
exception to the rule of endocrine control, of either gonadal or extragonadal
origin. Castration experiments, implantation of gonads of the opposite
sex, sometimes combined with experiments on regeneration of organs that
are sexually dimorphic—none of these have demonstrated an active role
for the gonads, nor control of somatic sexual characteristics by them
(reviewed in Naisse, 1965).
One exception can be pointed out, however. In the butterfly, Orgya
antiqua, sexual dimorphism is conspicuous; the female has only wing
stumps, although the wings are normal in the male. Paul (1937) conducted
an interesting experiment in this species. An imaginai disc of a male wing,
transplanted after the third larval molt into a female larva, develops into
a normal male wing, although transplantation into a male larva of a
imaginai wing disc taken from a female in the fourth stadium results in
formation of a male wing. This indicates that the male must produce a
hormonal substance capable of masculinizing the female somatic sexual
characteristics.
1. Sex Reversal in Lampyris noctiluca
The question has been resolved in a decisive manner in favor of endocrine
effects on sexual differentiation in insects by Naisse (1963, 1965) who was
able to show endocrine control of sexual differentiation in the coleopteran,
Lampyris noctiluca.
The adult form of L. noctiluca has a very clear-cut sexual dimorphism.
The female is wingless, slightly larger than the male, with a smaller head
and eyes of a reduced size. She possesses important luminescent organs
located on the last three sternites. The wings of the male are characteristic
of coleopterans, the eyes are well developed, and the light-producing
organs, less conspicuous, are situated on the side of the last visible sternite.
There is a summer cycle and a winter cycle. That which develops from
July to November will be considered. Males undergo four larval molts,
one pupal molt, and one imaginai molt. Females have one extra larval
molt. At the third molting, sexual differentiation is seen. In the male,
testicular cysts develop, and shortly before the pupal molt, spermatogenesis
begins. Maturation of gametes takes place at the time of molting to the
L. GALLIEN
ferentiation. These facts are in close approximation to those shown in
Bonellia, Crepidula, Ostrea, and Teredo. They lead in the direction of those
established in crustaceans, insects (lampyrids), and finally with certain
teleosts (Smaridae and Sparidae) and amphibians.
B. Endocrine Controls in Sexual Differentiation in Insects:
Apical Androgenic Tissue
For some time sexual differentiation in insects has seemed to be an
exception to the rule of endocrine control, of either gonadal or extragonadal
origin. Castration experiments, implantation of gonads of the opposite
sex, sometimes combined with experiments on regeneration of organs that
are sexually dimorphic—none of these have demonstrated an active role
for the gonads, nor control of somatic sexual characteristics by them
(reviewed in Naisse, 1965).
One exception can be pointed out, however. In the butterfly, Orgya
antiqua, sexual dimorphism is conspicuous; the female has only wing
stumps, although the wings are normal in the male. Paul (1937) conducted
an interesting experiment in this species. An imaginai disc of a male wing,
transplanted after the third larval molt into a female larva, develops into
a normal male wing, although transplantation into a male larva of a
imaginai wing disc taken from a female in the fourth stadium results in
formation of a male wing. This indicates that the male must produce a
hormonal substance capable of masculinizing the female somatic sexual
characteristics.
1. Sex Reversal in Lampyris noctiluca
The question has been resolved in a decisive manner in favor of endocrine
effects on sexual differentiation in insects by Naisse (1963, 1965) who was
able to show endocrine control of sexual differentiation in the coleopteran,
Lampyris noctiluca.
The adult form of L. noctiluca has a very clear-cut sexual dimorphism.
The female is wingless, slightly larger than the male, with a smaller head
and eyes of a reduced size. She possesses important luminescent organs
located on the last three sternites. The wings of the male are characteristic
of coleopterans, the eyes are well developed, and the light-producing
organs, less conspicuous, are situated on the side of the last visible sternite.
There is a summer cycle and a winter cycle. That which develops from
July to November will be considered. Males undergo four larval molts,
one pupal molt, and one imaginai molt. Females have one extra larval
molt. At the third molting, sexual differentiation is seen. In the male,
testicular cysts develop, and shortly before the pupal molt, spermatogenesis
begins. Maturation of gametes takes place at the time of molting to the