270
L. G A L L I E N
respond remain throughout the entire life of the individual. This situation
is probably associated with the nature of development of insects, which
becomes stabilized in the imaginai stage, while in crustaceans growth and
molting continue. Finally, note that in insects the androgenic endocrine
tissue is incorporated into the testis, rather than into the interstitial tissue
as in vertebrates. Among crustaceans the androgenic tissue is outside of the
gonad.
Naisse extended these experiments by implanting testes of different ages
into ovariectomized female larvae after the third, fourth, or fifth molt. The
adults obtained are masculinized by the active larval testes. The reproductive tract and the secondary sex characteristics are of the male type. But
these animals are sterile; the reproductive tract terminates in a blind sac
in the abdomen.
Naisse's experiments show that by itself the testis can masculinize a
female larva by an endocrine route. In all probability, this sex reversal results from the androgenic action of the testicular apical tissue functioning
during a specific stage in the life of the organism, namely, the second part
of larval life.
Similarly, the endocrine capacity of the ovary has been tested. Ovaries
of young female larvae after the fourth or fifth molt have been implanted
into males of various ages. The male host never changes sex. This indicates
that the ovary exerts no effect on the host. However, the transplanted
ovaries are transformed into testes. They are masculinized by the androgenic secretions of the male host. If ovaries are implanted into male pupae,
rather than larvae, they retain their ovarian structure. However, their
development is retarded. This confirms that at the pupal stage the androgenic hormone of the male has disappeared. Finally, ovaries of young differentiated female larvae, implanted into castrated males at the end of the
fourth or beginning of the fifth stadium, are transformed into testes. This
result seems to indicate that the androgenic hormone had already been
transmitted into the organism before castration.
2. Neurosecretory and Endocrine Systems in the Development of Sex in
Lampyris noctiluca
Some very interesting observations have been made in this regard on the
neurosecretory cells of the endocrine system: corpora cardiaca, corpora
allata, molting gland. The preliminary results (Naisse, 1965) tend to show a
difference between female and male activity of the neurosecretory cells in
these organs. In the male, certain neurosecretory cells become active during
the third and fourth molts, and secretion is abundant all the way up to the
adult stage. In females, on the other hand, the neurosecretory cells are less
numerous, and their activity, which is less important, does not begin until
the fifth stadium. Removal of the corpora cardiaca of young female larvae
L. G A L L I E N
respond remain throughout the entire life of the individual. This situation
is probably associated with the nature of development of insects, which
becomes stabilized in the imaginai stage, while in crustaceans growth and
molting continue. Finally, note that in insects the androgenic endocrine
tissue is incorporated into the testis, rather than into the interstitial tissue
as in vertebrates. Among crustaceans the androgenic tissue is outside of the
gonad.
Naisse extended these experiments by implanting testes of different ages
into ovariectomized female larvae after the third, fourth, or fifth molt. The
adults obtained are masculinized by the active larval testes. The reproductive tract and the secondary sex characteristics are of the male type. But
these animals are sterile; the reproductive tract terminates in a blind sac
in the abdomen.
Naisse's experiments show that by itself the testis can masculinize a
female larva by an endocrine route. In all probability, this sex reversal results from the androgenic action of the testicular apical tissue functioning
during a specific stage in the life of the organism, namely, the second part
of larval life.
Similarly, the endocrine capacity of the ovary has been tested. Ovaries
of young female larvae after the fourth or fifth molt have been implanted
into males of various ages. The male host never changes sex. This indicates
that the ovary exerts no effect on the host. However, the transplanted
ovaries are transformed into testes. They are masculinized by the androgenic secretions of the male host. If ovaries are implanted into male pupae,
rather than larvae, they retain their ovarian structure. However, their
development is retarded. This confirms that at the pupal stage the androgenic hormone of the male has disappeared. Finally, ovaries of young differentiated female larvae, implanted into castrated males at the end of the
fourth or beginning of the fifth stadium, are transformed into testes. This
result seems to indicate that the androgenic hormone had already been
transmitted into the organism before castration.
2. Neurosecretory and Endocrine Systems in the Development of Sex in
Lampyris noctiluca
Some very interesting observations have been made in this regard on the
neurosecretory cells of the endocrine system: corpora cardiaca, corpora
allata, molting gland. The preliminary results (Naisse, 1965) tend to show a
difference between female and male activity of the neurosecretory cells in
these organs. In the male, certain neurosecretory cells become active during
the third and fourth molts, and secretion is abundant all the way up to the
adult stage. In females, on the other hand, the neurosecretory cells are less
numerous, and their activity, which is less important, does not begin until
the fifth stadium. Removal of the corpora cardiaca of young female larvae