Even men have this nipple chakra, they spin. It can be seen in prana vision. It is more subtle than nano cells.

Here is the link to the old article written sometime ago:

https://inselfyoga.com/view-discussion/dance-of-kundalini-22-nipple-burst

Attached the nadi or subtle vein layout of nipple chakra to navel and sex bulb or kanda in the above post.