33 REPRODUCTIVE CHARACTERISTICS OF CLONED DOGS DERIVED FROM SOMATIC CELL NUCLEAR TRANSFER

Abstract

Several cloned dogs have been successfully produced by somatic cell nuclear transfer. However, there is no investigation of its reproductive characteristics including changes of hormone and ovarian follicles in cloned dogs. Thus, this study was to examine the onset of puberty, follicular dynamics, and reproductive hormone profiles in cloned beagle dogs. Two female cloned beagles, derived from fetal fibroblasts, were compared to 2 individual age- and weight-matched female beagles produced by natural breeding. All dogs were examined twice weekly from 6 months for the presence of swelling of the vulva and serosanguineous vaginal discharge, which were used as markers of the onset of proestrus. From the first day of proestrus, jugular venous blood samples were collected twice a day for hormonal analysis. Also, from the day when progesterone concentration was >1 ng mL^–1 until 5 days after ovulation, blood sampling was carried out 3 times a day. Ultrasound examination of ovaries and uterus was performed daily from the onset of proestrous until 5th day post-ovulation. Cloned female dogs (332.5 ± 1.5 days) reached puberty later than controls (300 ± 8 days). The mean number of ovarian follicles was 4.5 ± 0.5 v. 6.5 ± 0.5 for clones and controls, respectively. The largest size of ovarian follicles in clones and controls detected by ultrasound were 0.6 ± 0.03 v. 0.69 ± 0.07 cm, respectively. It took 8 days from the initiation of vulvar bleeding to the LH peak in all beagles. Moreover, there were no differences in the profile of hormonal changes (LH, FSH, estradiol, and progesterone) in cloned and control beagles. These results demonstrate that cloned dogs have normal development of reproduction.

This study was financially supported by the Korean MEST, through KOSEF (grant # M10625030005-08N250300510) and the BK21 program for Veterinary Science.