异常型窄脊江豚的体型参数及肝脏组织学分析

Analysis of somatotype parameters and liver histology of an abnormal finless porpoise at the Yangtze River Estuary

摘要:

对2016年2月在上海崇明岛水域发现的1头超重雌性窄脊江豚东亚亚种遗骸作了年龄鉴定，并将体型参数、腹壁脂肪层及肝脏组织等与同龄的正常个体作了比较。分析显示，该江豚为2龄，体长115.0 cm、体质量29.9 kg、最大体围86.2 cm、体质指数（BMI）22.6 kg/m²、体围指数（BGI）75.0%和腹部脂肪层厚度3.5~4.3 cm，均明显大于同一水域的其他8头同龄个体。参照人类体质指数（BMI）等判断肥胖的方法和标准，发现该江豚已达到肥胖程度。实验样本的肝脏质量占体质量3.3%，肝脂肪含量高达9.27%±1.67%，脂肪占肝脏切面的体积也达40.81%±2.09%，分别是正常或对照样本的1.4、2.63和1.75倍。肉眼观察发现，实验江豚的肝脏表面凹凸粗糙，内部出现了短肌纤维束脂肪样的病变。石蜡切片显示，低倍镜下有大量的嗜酸性粒细胞浸润；高倍镜下轻度病变部位的肝细胞已发生了明显的空泡状病变，高度病变部位仅可见完全坏死的肝细胞。研究表明，该肥胖江豚已发生了严重的脂肪肝病变，并与体型参数、腹壁脂肪厚度存在着相关性，这些发现对江豚的人工驯养和迁地保护具有积极的指导意义。

Abstract:

In this paper, we determined the age of an overweight female narrow-ridged finless porpoise Neophocaena asiaeorientalis sunameri remains which was found in February 2016 in Shanghai Chongming Island, then compared its somatotype parameters, thickness of the abdomen fat and liver tissue with normal individuals of the same age. The analysis shows that the N. asiaeorientalis sunameri is two years old, its body length is 115.0 cm, body weight is 29.9 kg, the largest body girth is 86.2 cm, body mass index (BMI) is 22.6 kg/m², body girth index (BGI) is 75.0%, thickness of the abdomen fat is 3.5-4.3 cm, all of these parameters are significantly higher than other eight remains in the same estuary. Based on the methodologies and criteria of judging obesity in humans, such as the BMI, a common measure of obesity, we found that this N. asiaeorientalis sunameri is obese. The liver weight of the experimental sample is about 3.3% of the body weight, fat fraction in liver reaches up to 9.27%±1.67%, fat accounts for the liver section also reaches 40.81%±2.09%. Separately, each percentage is significantly higher than normal or control individuals, the multiples are 1.4 times, 2.63 times and 1.75 times in sequence. In our ocular inspection, the liver surface of experimental sample is rough, it reveals intenal lesions with short myofiber and hepatic steatosis. Paraffin sections show that the mass eosinophil infiltration in the tissue in low-power scan; At high magnification, the hepatocyte in mild lesion area occurs to obvious pathological cavitation, only completely necrotic hepatocyte can be seen in highly pathological change area. Research indicated that this obesity N. asiaeorientalis sunameri has evolved serious adiposis hepatica which was correlated to its somatotype parameters and thickness of the abdomen fat. These findings have a certain guiding significance for finless porpoise's domestication and ex situ conservation.