你可以用by换掉of. 但, of似乎更静态，尽管字典上一般没有这类例句。

made of
formed of

我去查了一下，个人感觉应该属于介词短语充当副词的修饰语，表示地点。
把of改为by个人感觉并不合适
”of the circumferential slots” 就介词短语 修饰前面的副词“proximally”，表示地点
这里的of并不是与form连用
介词短语充当副词的修饰语的类似用法还有如下例句：
Later in the day the situation had improved slightly.
Downstairs in the kitchen were several other guests

再举一个例句：
AKT activation occurs downstream of phosphoinositide 3-kinase。