Singh Namram S, Dixit Anand S, Khanikar Debashish
Department of Zoology, Cotton University, Guwahati, 781001, Assam, India.
Department of Zoology, North-Eastern Hill University, Shillong, 793022, Meghalaya, India.
Microsc Microanal. 2021 Oct 18:1-9. doi: 10.1017/S1431927621012885.
We studied the fine histological structures of pecten oculi of the Eurasian tree sparrow using various microscopy techniques. The pecten of the tree sparrow was found to be of a pleated type comprising of pleats, bridges, and base. The light microscopic study revealed further that the pleats consist of capillaries of varying sizes, blood vessels, and numerous pigmented cells that give them a black color. Histochemical studies of pecten showed a large deposition of lipid droplets, which were more abundant in the basal area. The transmission electron microscopy displayed capillaries and blood vessels that remain surrounded by a thick fibrous basal membrane. They are formed of endothelial cells having a large lumen and abluminal area with microfolds. Interstitial spaces were found filled with rounded melanocytes, electron-dense pigment granules, and mitochondria. Observations under the scanning electron microscope revealed the presence of a dense vascular network of capillaries and vessels. In addition, large hyalocytes were also observed on the surface of the pleats. The above observations suggest that the histological structure of the pecten of the tree sparrow resembles those present in the pecten of other diurnal birds. However, further investigation is required to ascertain its functional role in birds.
我们使用各种显微镜技术研究了欧亚树麻雀眼梳膜的精细组织学结构。发现树麻雀的眼梳膜为褶皱型，由褶皱、桥和基部组成。光学显微镜研究进一步显示，褶皱由大小各异的毛细血管、血管和大量使其呈现黑色的色素细胞组成。眼梳膜的组织化学研究显示有大量脂滴沉积，在基部区域更为丰富。透射电子显微镜显示毛细血管和血管被一层厚厚的纤维基膜包围。它们由具有大管腔和无腔区域且带有微褶皱的内皮细胞形成。发现间质空间充满圆形黑素细胞、电子致密色素颗粒和线粒体。扫描电子显微镜下的观察显示存在密集的毛细血管和血管网络。此外，在褶皱表面还观察到大型透明细胞。上述观察结果表明，树麻雀眼梳膜的组织结构与其他昼行性鸟类眼梳膜中的结构相似。然而，需要进一步研究以确定其在鸟类中的功能作用。
