I've weighed in on this topic more than once and I am here to tell you that with time and dedication you CAN increase PERMANENTLY stretch, lengthen, and increase ANY portion of the human body tissues. I know some will argue this, and I welcome this, and considering my background (yes it is in medicine) I’m prepared.
There is a process in which prior to surgery for some patients saline filled pouches are placed under the skin and slowly over the course of weeks to months filled with saline in an effort to stretch tissue. This process can be duplicated with the penis via mechanical pumping. Hold your arguments! The increased pumped feeling and look will over time (hours) decrease however the skin (tissues) will have been expanded and WILL increase. Direct your attention to the small tribes of Africa where the increasing number of rings are placed around the neck of a woman to elongate the neck, which obviously includes muscle, tissue, and BONE. These bones DO NOT separate but instead increase in thickness to continue ‘contact’.
Further, consider modern day earlobes of those who use spacers or the lips of tribes of Africa. This stretching of tissues has been around for years and will never end but like the lips and earlobes where there isn’t any boney structure when the mechanical stretching device is removed it will go “limp”, pardon the pun. BUT the tissues will expand and when you, speaking of the penis, become erect yes overtime there will be an increase in length and size.