Effects of exogenous estrogen on the differentiation and development of the right oviduct in female chickens
Masuda, S. (Kyushu Tokai Univ., Kumamoto (Japan)) | Koyanagi, F.
On day 5 of incubation, 0.64 mg of estradiol benzoate (EB) was administered to fertilized eggs to investigate its effects on the differentiation and development of the oviduct in female chickens. The increases of body and ovary weights of treated females in 0 to 366 days old were similar to those of females not treated with EB (control). However, thirty one % of the mature treated females did not produce any eggs. The egg production rate of the treated females that produced eggs was low, and the first egg production was delayed, although there were large individual variations among the treated females. A right oviduct at various developmental stages was seen in every treated female; there was a significant negative correlation between egg production rate and the weight of the right oviduct (p< 0.01), and a significant positive correlation between egg production rate and the weight of the left oviduct (p< 0.01). The number of yellow follicles in the ovary of the treated females was similar to those of the control, but intraperitoneal ovulations were observed in most of the treated females. These findings suggest that suppression of anti-Muellerian hormone by estrogen in embryogenesis allows the development of the right Muellerian duct, which differentiates and develops into an oviduct. One of the causes of the reduced egg production in the mature treated females could be inhibition of the normal differentiation and development of the left Muellerian duct by exogenous estrogen, thus resulting in a functionally immature left oviduct
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