青蛙(黑斑蛙)视网膜存在离心纤维吗?

ARE THERE CENTRIFUGAL FIBERS TO THE RETINA IN THE FROG(RANA NIGROMACULATA)?

将一组黑斑蛙(Rana nigromacizlata)一侧视顶盖的一部或大部切除,另一组青蛙从口腔内切断一侧视神经,手术后前者存活12~26天,后者存活11~22天。将两侧视网膜(连带一小段视神经)均做冰冻切片,厚25微米,用染溃变纤维和末梢的Ebbesson-Heimer方法染色,以正常动物的视网膜和视神经做为对照。在光学显微镜下观察并进行比较,未发现任何显示溃变的证据。据此推断青蛙视网膜不存在来自中枢的离心纤维。

Parts of the left tecta of the frogs were removed in one group.In another group,the left optic nerves of the frogs were cut through the mouth.The first group of animals survived for 12~26days and the second group 11~22 days.Both right and left retinas(with a small piece of optic nerve attached)were sectioned radially at 25μm on a freezing microtome and stained by Ebbesson-Heimer’s method which allow degenerating fibers and terminals stained specially.We did not find any evidences showing degeneration.We concluded that centrifugal fibers coming from the centers to the retinas were absent in the frog.