Here are some nice round structures and were they always near the nuclear membrane i would count them as tangentially sectioned nuclear pores since they are sized so similarly (though i have not seen any central densities like i see in nuclear pores where actual proteins are being imported or exported. There are also some profiles of membrane (with contents) that are pretty linear for golgi seen as well, and don’t quite fit that golgi iconic morphology. This is a fetal hepatocyte. Arrows point to pore and to similarly sized rounded structures that are not likely to be tangentially section pores from the nucleus shown.
Might be a section of a clathrin coated vesicle…. when i google it, this wonderful model came up.  Sure looks (at 100nm) like it could work.  What a marvelous amount of research has provided the molecular structure (triskelion) shown by them (on wikipedia) in blue.