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Male green anole lizards court females using a red throat fan (dewlap) and copulate by intromitting one of two penises (hemipenes). These structures begin sexually monomorphic, but by adulthood males have larger dewlaps, only males have hemipenes, and many of the neuromuscular components of both systems show male-biased dimorphisms. We hypothesized that testosterone (T), which increases in juvenile males but not females about a month after hatching, facilitates masculinization. To test this idea, on post-hatching day 30, gonadally intact females received either a blank or T implant, and males were either castrated or sham-castrated. At day 90, juveniles were euthanized and the length of the cartilage and cross-sectional areas of the muscle fibers and motoneurons required for dewlap extension were examined. We also measured the cross-sectional areas of the hemipenes and associated muscle fibers and motoneurons, and counted the motoneurons. T-treated females had longer cartilages and larger dewlap muscle fibers compared to those with blank implants. No effects on motoneurons were detected, and no females possessed hemipenes or associated musculature. In males, castration produced shorter dewlap cartilages and smaller hemipenes; other measures were not affected by treatment. These data indicate that components of the dewlap system differentiate relatively late in development, that T likely mediates the process, and that although components of the copulatory system are plastic in juvenile males, sexual differentiation of peripheral features is complete before day 30. The data also suggest that target structures (dewlap cartilage and hemipenes), compared to their neuromuscular effectors, are particularly sensitive to developmental T exposure. 相似文献
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Two new species of Fabaeformiscandona and collections of Fabaeformiscandona japonica (Okubo, 1990. Bulletin Biogeography Society of Japan 45: 39–50) from Japan have provided an opportunity to study the copulatory
behaviour and sexual morphology of these species. The male uses the large fifth limb palps to force open the female carapace
for copulation. However, the female has an enlarged overlapping flap over the posterior of the carapace which appears to hinder
the male from opening the carapace, thus the female retains some control over potential mates. During copulation, the males’
fifth limbs, caudal ramus and m process of the hemipenes and the females’ protrusion of the female reproductive organ play a crucial role in providing a
secure interface between the sexual organs to allow for the transfer of the giant spermatozoa. Development of the sexual organs
in both sexes begins during the A-2 instar, and the protrusion of the female genital lobe begins to form during the A-1 instar. 相似文献
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