In both types of feather, the barbules that extend from the barb ramus grow from a single layer of cells, called the barbule plate, on the periphery of the barb ridge. 而不论是何种羽毛，从羽枝主枝延伸出来的羽小枝，都从羽枝脊表面叫做「羽小枝板」的单层细胞长出来。
Each barb branches into barbules, which link to one another by hooks.
每根羽支分拨成小羽，小羽通过钩子相互连接。
Space – Verge Science
And lots of times, there are little feather barbules in there that we can look at the microscopic characters
很多时候， 里面有小羽毛，我们可以看到微观特征。
PBS地球-动物趣闻
The central part of the feather became a hardened structure called a rachis, with lots of little barbs and barbules, creating the vanes of the feather.