Usa n mature sex
Although this trial was conducted more than three times for each fish, no fertilized egg was obtained.The tissues in the control and experimental groups were then subjected to histochemical examination (Supplementary Fig. The morphology of ovarian tissues in the control fish showed no significant change compared to the ovaries from untreated females (Figure 3).To allow us to monitor the changes in the ovaries of living fish during fadrozole administration, we used ovarian fluorescent and transparent transgenic zebrafish lines.The transparent strain of zebrafish, roy, is deficient in the production of iridescent color by iridophores, and the viscera and reproductive organs are thus visible from the outside of the fish body (Figure 1A).Female-to-male sex change is associated with a decrease in estrogen levels, followed by an increase in androgen levels.Estrogens are produced by the conversion of aromatizable androgens by cytochrome P450 aromatase (P450arom), and the actions of P450arom are essential for sex differentiation and ovarian development in fish and other vertebrates.(C) Follicle-enclosed oocytes in various stages (1 to 4) and after germinal vesicle breakdown (GVBD) were separated from the ovary. Although ovary size was reduced within several months, even in fish under the control conditions in a group of females alone (27%, n = 11), the ovaries underwent oscillatory changes in size during the treatment.The oscillatory intervals were approximately two weeks but were not constant among individuals.
Recently, it has been reported that the massive, male-specific disappearance of oocytes from the gonad during the transition from ovary-like tissue to testis tissue is caused by apoptosis.
In Japanese flounder (Paralichthys olivaceus) and tilapia (Oreochromis niloticus), brief treatment with AI during sex differentiation causes a sex reversal in which genetic females develop into phenotypically normal males.
In contrast, oocytes in the female ovaries continue to grow to maturation.
Artificial fertilization using sperm from the sex-changed females was successful.
These results demonstrated that sex plasticity remains in the mature ovaries of this species.A 5-month AI treatment caused retraction of the ovaries after which testes-like organs appeared, and cyst structures filled with spermatozoa-like cells were observed in sections of these tissues.