[Free-from-Nuts]

The lovely Japanese newhalf, Miran, is one of my all time favourites. she is both very beautiful and an excellent actress and model.
I have often wondered about her scrotum, she appears to have an unusual feature running all the middle all the way from the base of her pretty cock to her behind. The jpeg shows clearly the feature that I would describe as a ridge.
Does anyone know what this ridge is. My thoughts are that this is some kind of scar tissue. From the copious quantities of milky cum she invariably produces, if it is a scar, it is not from an orchiectomy.
Any ideas on this?