Question

what is the fenestration in nephron?​

Answer 1

This is a fenestrated endothelium, meaning that there are pores (fenestrae or fenestrations) that penetrate through the endothelial cells. The next layer is the glomerular basement membrane, a shared basement membrane between the two epithelia (endothelium and podocytes).

Answer 2

This is a fenestrated endothelium meaning that there are pores that penetrate through the endothelial cells