Observations on the female reproductive cycles of captive Asian yellow pond turtles (Mauremys mutica) with radiography and ultrasonography.

The annual reproductive cycle of 27 female Mauremys mutica was observed by radiography and ultrasonography from April 2006 to August 2007. Radiography was used to monitor clutch size and ultrasonography was used to monitor changes in the ovarian follicles. The follicles started to enlarge in September and became preovulatory in January. The mean maximum follicle diameter of ovulation was 18.30+/-1.44 mm, and ovulation occurred from March through August. Eggs were laid between April and August. Turtles entered latent period in early August and the maximum follicular size was at a low of 13.22+/-2.36 mm in late September. The vitellogenesis of the next reproductive cycle began in October. The 24 adult females laid 56 clutches containing a total of 227 eggs. Average clutch size was 4.05 eggs (range 1-8) and there were 2.33 clutches (range 1-4) per female. Egg shell images were first observed on the sixth or seventh day after ovulation. The oviductal period averaged 6.9 weeks (range 2-16 weeks) on the first clutch, 3.4 weeks (range 2-8 weeks) on the second, and 2.75 weeks (range 2-6 weeks) for the third. Radiography and ultrasonography are non-invasive and convenient methods to evaluate the reproductive cycle of female M. mutica. They should be applicable to other turtles and should greatly enhance knowledge of reproductive physiology.