以放射線學及超音波影像學觀察雌性斑龜生殖週期之變化

Abstract

台灣原生種淡水龜中，除了中華鱉、斑龜外皆被列入保育類動物， 斑龜雖未被列入保育類動物，但近年來由於土地利用形式改變，淡水龜生 存之水塘及溪流，超過70%已經過河岸整治工程破壞，河岸、溪流周遭多 已水泥化，淡水龜賴以生存之棲地急速惡化及消失，因而造成淡水龜數量 銳減，棲息其中之斑龜也不例外。此外外來物種的侵入及人類因應龜板需 求的濫捕，更讓斑龜之處境雪上加霜。目前國內外極少有關於斑龜生殖生 理方面之研究，可藉由斑龜繁殖期之研究，了解其生殖週期，不但可提供 斑龜復育繁殖之運用，另外更可藉此了解河岸改變對生殖生理之衝擊，可 提供河岸施工單位進行河川整治時之參考。 2004 年3 月至2005 年8 月期間，11 隻斑龜及2004 年10 月增添之 11 隻新斑龜，每月進行非侵入性超音波監測，探測最大濾泡世系之變化， 並且輔以放射線學以了解生殖週期中濾泡之成長發育、排卵及萎縮，探測 輸卵管內卵至硬殼蛋的形成過程及產蛋之情形。 從研究結論得知，發育成熟雌斑龜9 月開始濾泡成長，濾泡於10-12 月增長成排卵前濾泡 (16.6 ± 0.4mm)，於每年溫度回升後之2 月及3 月 間排卵，排卵前後濾泡直徑分別為18.0 ± 0.9 mm 及17.5 ± 1.3 mm，並 於4 至6 月間完成產蛋，產蛋前後濾泡直徑分別為18.5 ± 1.1 mm 及17.2 ± 1.5 mm，濾泡於產蛋後的4-8 月份開始萎縮下降是為潛伏期，潛伏期濾 泡直徑最小值為9.4 ± 1.6 mm，之後再次生殖生理循環。在2004 年生殖 週期中，11 隻斑龜有7 隻斑龜懷蛋，出現7 個產蛋組，總共產下65 個蛋， 每產蛋組之蛋數目 (clutch size) 為9.3 ± 1.7 個 (N=7，範圍6-11 個)。 在2005 年的生殖週期中，22 隻斑龜共19 隻斑龜懷蛋，其中8 個體產下第二個產蛋組，總計有27 個產蛋組、共產下223 顆蛋，產蛋組之蛋數目 8.3 ± 2.3 個 (N=22，範圍1-13 個)，產蛋個體平均年產1.4 (27/ 19) 窩 蛋。根據超音波觀測得知，排卵前濾泡無顯著影像學變化，卵全數排出歷 時24-48 小時，排卵後第5 至6 天可由超音波觀測極淡之蛋殼影像，另外 放射線學上，發現兩組蛋殼厚度不ㄧ的蛋，是斑龜產出第二個產蛋組的直 接證據，族群平均體重在各種生殖週期中並無顯著差異。 就本身查詢論文資料中，甚少斑龜相關文獻，未曾發現以超音波對斑 龜進行詳細生殖週期之研究，故以超音波持續探測圈飼斑龜之最大世系濾 泡，除可建立正常產蛋斑龜之卵巢週期性變化，也可提供野生斑龜之生殖 研究依據；而第二個產蛋組的放射線學發現及超音波與放射線學的時程對 照，也可提供龜類生殖研究之參考。這些非侵入性且可靠的監測方式，兼 顧了便利性及實用性，將來更可運用於其他淡水龜之生殖生理建立，以作 為復育之用。 本論文對於淡水龜之生殖生理模式的建立及進行淡水龜類保育復育 及河川施工參考，具有重要之參考價值。

Except Ocadia sinensis, all of the freshwater turtles were listed as protected animals in Taiwan. Recently, utilization on land was changed and over 70% rivers and ponds where the freshwater turtles inhabit in was engineered. The bank of rivers and brooks were replaced with cement and it caused the habitats of freshwater turtles disappear rapidly. The disappearance of habitats cause the numbers of freshwater turtles decrease dramatically. Ocadia sinensis was also in the dangerous situation. The invasion of foreign species and the excess capture of wild turtles owing to the need of bone plate were also made Ocadia sinensis disappear rapidly. There were few researchs about reproductive cycle of Ocadia sinensis. To study the reproductive stage of Ocadia sinensis not only help realize the reproductive physiology but also could apply to the conservation. Realize the impaction on reproductive physiology under changing the river bank, and it could be refered to river engineering for conservation freshwater turtles. From March of 2004 to August of 2005, the experiment has detected 11 turtles and another 11 turtles which were added in October of 2004. The experiment methods were that detected the largest follicular follicles with noninvasive ultrasound and radiology was also involved. The detection methods could realize the the growth of follicles, ovulation and atrophic follicles. It also could find the process from the ovum to hard-shell egg and the situation of oviposition. According to the result, the follicles of gravid turtles grew on September, and became preovulatory follicles (16.6 ± 0.4mm) among November to December. Ovulation occured among February to March when the temperature rose again from minimum. Before and after ovulation, the follicular diameters were 18.0 ± 0.9 mm and 17.5 ± 1.3 mm respectively. Oviposition was completed among April to June. Before and after oviposition, the follicular diameters were 18.5 ± 1.1 mm and 17.2 ± 1.5 mm respectively. The latent period after ovipostion which follicles appeared atrophic among April to August. The minimum diameter of follicles was 9.4 ± 1.6 mm. After the latent period the reproductive cycle recycled. Seven out of eleven turtles were gravid and laid a total of 65 eggs in the reproductive cycle of 2004. The average clutch size was 9.3 ± 1.7 eggs (N=7. range 6-11 eggs). Nineteen out of twenty-two turtles were gravid and laid a total of 223 eggs in reproductive cycle of 2005. Eight out of nineteen turtles which were gravid laid second clutch. Clutch size was 8.3 ± 2.3 (N=22, range 1-13 eggs). The gravid turtles average laid 1.4 (27/19) clutches per year. According the result of daily detection with ultrasound, there was no change of the image of preovulatory follicles just before ovulation. It takes 24-48 hrs to complete ovulation. Fifth to sixth day after the ovulation, the light egg outline started to be found on radiology. In the radiology, there were two type of egg shell with different thickness. It was the direct evidence of gravid turtles laid second clutch. There was no difference in average body weight of group when turtles in different reproductive status. According my search for paper of Ocadia sinensis, there were few papers about Ocadia sinensis. And no research of reproductive cycles of Ocadia sinensis with ultrasound was found . Detection the change of the follicles of largest group, it not only could help to realize the ovarian cycle of Ocadia sinensis but also support the basis of reproductive physiology to study wild group. The finding of radiological image of second clutch and the timing contrast between radiology and ultrasound during the ovulation process could provide references to study reproductive cycle of chelonian. The detection methods were noninvasive and reliable, and it also gave consideration to convenience and practicality. These detection models with ultrasonography could be applied to set up the reproductive physiology of other freshwater turtles. The study was extremely valuable while studying the reproductive models of Ocadia sinensis, taking conservative concerns and engineering of river.