幼龄红嘴相思鸟小脑皮质组织学结构

Histological Observation on the Development of Cerebellar Cortex in Red-billed Leiothrix(Leiothrix lutea) after Early Hatching

为了探讨不同日龄幼龄红嘴相思鸟(Leiothrix lutea)小脑皮质的组织学结构变化,分别以1、5、9日龄红嘴相思鸟为研究对象,通过H.E和甲苯胺蓝法进行染色,光镜下观察红嘴相思鸟小脑冠状切面的显微结构。结果显示,1日龄时,小脑皮层由外颗粒层(EGL)、浦肯野细胞层(PCL)和内颗粒层(IGL)3层构成,外颗粒层较厚且清晰,而浦肯野细胞层和内颗粒层界限不清楚;5日龄和9日龄时,小脑皮质均可见外颗粒层、分子层(ML)、浦肯野细胞层和内颗粒层4层结构。对3个日龄红嘴相思鸟小脑皮质各层厚度进行单因素方差分析,随日龄增长,小脑皮质、分子层和内颗粒层厚度极显著增厚(P<0.01),浦肯野细胞体积也极显著增加(P<0.01);外颗粒层厚度变化不明显(P>0.05),呈现先增厚后变薄的趋势,与皮质厚度的比例逐渐减小。研究表明,幼龄红嘴相思鸟在出生后,随日龄增长,小脑皮质层逐渐发育成熟。内颗粒层与外颗粒层的相对变化规律表明,内颗粒层细胞是由外颗粒层迁移而来的。

To study the histological changes of cerebellar cortex of immature red-billed leiothrix （Leiothrix lutea） at different days of age, brains were sampled from red-billed leiothrixs at 1, 5 and 9 days of age. By using H.E and toluidine blue staining as well as microscopy, the coronal section of the cerebellum was observed to analyze the changes of cellular and postnatal structural patterns, and all the data were analyzed with one-way ANCOVA. The H.E staining showed that the eerebellar cortex of red-billed leiothrix at 1 day of age consisted of three layers, namely external granular layer （EGL）, unclear Purkinje cell layer （PCL） and internal granular layer （IGL）; the external granular layer was obvious, but the margin of Purkinje cell layer and internal granular layer was not distinct （Fig. la, d）. At 5 and 9 days of age, a clear four-layer structure was observed, including external granular layer, molecular layer （ML）, Purkinje cell layer and internal granular layer （IGL） （Fig. lb - c, e - f）. With the increase of the age, the thicknesses of cortex, molecular layer and internal granular layer were significantly increased （P 〈 0.01）. Toluidine blue staining showed clearly that the size of Purkinje cells was significantly increased with the increase of age. At 1 day of age, the Purkinje cell was small with pyriform and the Nissl body was dark-colored （Fig. 2a, b）; at 5 days of age, the Purkinje cells were enlarged （Fig. 2c, d）. At 9 days of age, the size of the Purkinje cells was increased and the boundary between Purkinje cell layer and internal granular layer was apparent （Fig. 2e, f）. Although the thickness of external granular layer became thinner after a slight increase, there was no significant change （P 〉 0.05） （Table 1）. There was a reduced proportion of the external granular layer to the cortex （Table 2）. Also the index of internal granular layer to the cortex was increased （Table 2）. The results showed that the histological structure of cerebellar cortex was gradually matured in red-billed leiothrixs after early hatching. The changes of external granular layer and internal granular layer suggested that the granular cells in internal granular layer might migrate from external granular layer.