Observation of reproductive cycles of female Asian yellow pond turtle（Mauremys mutica）in captivity with radiology and ultrasonography

• Main Authors: Yuan-Yu Cheng, 鄭元毓
• Other Authors: Chau-Hwu chi
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/65517851179951575901

碩士 === 臺灣大學 === 獸醫學研究所 === 95 === There were reasons that make Mauremys mutica endangered but only few researches about reproductive physiology of them were cited. We combined non-invasive ultrasound and radiology together to monitor reproductive cycle of Mauremys mutica. This study is very important for us to understand reproductive physiology of Mauremys mutica and provide great help in conservation of them. The reproductive cycle of 27 female Mauremys mutica was studied from April 2006 to June 2007. We monitored the change of largest follicle by ultrasonography twice a month to collect a series of images and also used radiology to monitor clutch size. The study comprised the annualised observation of reproductive cycle by radiology and ultrasonography. Radiology is used to monitor clutch size; while ultrasonography is utilized to monitor the change of ovaries and follicles. It reaches a conclusion that the follicles start to enlarge from September to January. Preovulatory follicles are averaged in diameter of 18.30 ± 1.44 mm. Then the ovulation occurred continually between March and August with eggs laid successfully between April and August. After oviposition, female turtles came into latent period in early August with follicles decreased to minimum of 13.22 ± 2.36 mm in late September. Later on, the vitelloginesis of next reproductive cycle proceeded since October. In breeding season of 2006, 24 of 27 adult female turtles were gravid. There were 227 eggs found in 56 clutches, therefore, every turtle had 2.33 clutches (range 1-4) and 4.05 eggs (range 1-8) per clutch in average. In 2007, 25 of 27 adult female turtles were gravid. There were 214 eggs found in 50 clutches, therefore, every turtle had 2 clutches (range 1-4) and 4.26 eggs (range 1-8) per clutch in average By intensive monitoring of radiology after ovulation, we can find egg shell image of the 6th - 7th day after the ovulation, but we accurate know the clutch size until the 7th - 9th day after ovulation. Afterward, shell would get much denser and the images of egg shell under Radiology would get much clear too. According to the intensive observation during ovulation process by ultrasonography, the follicles have ovulated within 24-48 hours. The day that we found ova secret by follicle in ultrasound was defined as Day 1. Ova were not surrounded by rich albumin and shell membrane on Day 1, and it was surrounded by anechoic albumin on Day 2, then covered with shell membrane on Day 3. On Day 3, shell images were found by ultrasonography, and calcification was processing since then. As the deposition of calcium on the shell membrane, inner content of the eggs can’t be seen clearly after 2 weeks of ovulation, and yolk and albumin can’t be observed after 3 weeks of ovulation. Therefore, it is about 17-18 days that it is in vain to observe egg’s inner content since calcium began to deposit on the shell membrane. The average of oviductal period in the first clutch is 6.9 weeks (range 2-16 weeks), 3.4 weeks (range 2-8 weeks) in the second clutch, 2.75 weeks (range 2-6 weeks) in the third clutch and 4 weeks (2 and 6 weeks) in the fourth clutch. It comes to a conclusion that longer clutch retention time was needed in first clutch, and shorter time was needed with the following clutches. The period between two ovulation time was defined as gravid interval, and the interval between the first and the second clutch is 6.6 weeks (range 2-12 weeks), 4 weeks (range 2-6 weeks) between the second and the third clutch and 3 weeks (2 and 4 weeks) between the third and the fourth clutch. As the result it revealed that the gravid interval seemed to be shorter while clutches increasing.