中文摘要：

墨龙是一种由红鲫进化来的龙睛种金鱼（Carassius auratus）。随机取体长10—12 cm,重约35 g的墨龙和红鲫各4尾,解剖取出整个眼球及脑,并常规石蜡切片,HE染色。在光学显微镜下观察墨龙和红鲫的视网膜、视盖系统的显微结构变化并比较各层厚度,发现与红鲫相比,墨龙视网膜的总厚度下降29.9%,其中外网状层厚度增加2.5%、内网状层厚度增加11.8%;而内核层厚度下降21.6%、外核层厚度降低35.6%,神经节细胞层、杆锥层也变薄,且后两者分层不规则;墨龙视盖壁整体厚度增加28.9%,其中除围脑室层厚度减少22.6%外,中央纤维层厚度增加12.8%,中央细胞层厚度增加30.6%,表面纤维层厚度增加21.9%,且纤维远较红鲫密集,视神经层厚度增加91.7%,边缘层厚度增加35.6%。结果表明长期的人工选择不但改变了墨龙的外形,而且使其中枢神经组织结构也发生了较大变化,并推测墨龙的眼球直径及视网膜面积较大,从而导致自视网膜传入视盖的纤维增多,是视网膜和视盖中的传递神经冲动的神经元、神经纤维所在层段增厚的主要原因;同时墨龙视网膜中色素上皮层向杆锥层交错对插,富含神经元的视网膜外核层、内核层以及视盖中的围脑室层厚度也降低,可以减少因视网膜面积大而造成的强光伤害;此外由于墨龙的围脑室层厚度降低,导致其游动及平衡能力较红鲫差。

英文摘要：

The black dragoneye,a kind of dragoneye goldfish（Carassius auratus）,has evolved from the red crucian.Four black dragoneyes and four red crucians,each being 10—12 cm long and weighing 35 g,were taken randomly and dissected.Their brains and eye-balls were observed using routine paraffin section and HE staining.The microscopic structures of the retinas and optic tectums of black dragoneye and the red crucian were studied under an optical microscope.We found that,compared with the red crucian,the retina of black dragoneye was 29.9% thinner,of which the outer plexiform layer increased 2.5%,and the inner plexiform layer increased 11.8%,while the inner nuclear layer decreased 21.6%,and the outer nuclear layer decreased 35.6%.Besides,the ganglion cell layer and the photoreceptor layer were thinner and irregular.However,optic tectum in black dragoneye was 28.9% thicker than that of the red crucian,except that the stratum periventriculare layer decreased 22.6%,all layers were incrassate,with the stratum album central layer increased 12.8%,the stratum griseum central layer increased 30.6%,the stratum fibrosum et griseum superficiale layer whose fibers were 21.9% denser than that of the red crusian,the stratum opticum layer was 91.7% thicker and the stratum marginal layer was 35.6% thicker.The results showed that the central nervous system of black dragoneye varied widely due to artificial selection and breeding.It can be inferred that the larger eyeball diameter and retina area of the black dragoneye resulted in an increase of fibers transmitted from the retina to the optic tectum,which probably was the main cause for the thicker layers of neurons and nerve fibers that transmit nervous impulse.To reduce the damage caused by strong light,the pigment epithelium layer moved to the photoreceptor layer interlacedly,and the inner nuclear layer of and outer nuclear layer the retina as well as the stratum periventriculare layer in its optic tectum became thinner.In addition,the thickness of the stratum periventriculare layer