Terminal phase males stimulate ovarian
function and inhibit sex change in the protogynous wrasse Thalassoma
duperrey.
Morrey CE, Nagahama Y, Grau EG.
Laboratory of Reproductive Biology, National Institute for Basic
Biology, Okazaki 444-8585, Japan. morrey@nibb.ac.jp
Under experimental conditions, the probability of sex change
in the protogynous wrasse Thalassoma duperrey is determined largely
by an individual's relative size within a social group. Natural
populations, however, contain two distinct male phenotypes that
may also play a role in regulating sex change. To investigate
potential effects of male phenotype, the ability to change sex,
ovarian histology and serum estradiol-17 beta levels were examined
in females maintained under controlled social settings. Large
females housed with smaller or larger terminal phase males had
significantly larger gonadosomatic indices than females housed
singly, with other females or with smaller initial phase males.
Similarly, ovaries of females housed with terminal phase males
showed no histological evidence of sex change, whereas large females
from other social groupings were in advanced stages of sex change.
These results demonstrate terminal phase males inhibit sex change
regardless of their size relative to the female. Furthermore,
gonadosomatic indices, ovarian histology, and serum estradiol-17
beta levels of females housed with terminal phase males indicate
normal ovarian function whereas ovaries of other treatment groups
appear quiescent or are undergoing sex change. Consequently, terminal
phase males may be required for normal ovarian development which
may, in turn, inhibit sex change in T. duperrey.
Sex Change Publications
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