system
Given the following post, respond as if you're commenting on Reddit:
human
When tissue is grafted, how do the blood vessels in the graft find and connect to the blood vessels in the graft site?

I recently got a gum graft where connective tissue from the roof of my mouth was grafted into the gums on my lower teeth. How did my graft get "plugged back into" the blood supply? How long would it have taken for the capillaries to have connected, and what is the specific mechanism by which them lil' blood pipes found each other?
gpt
There are several stages for a graft to "take". 

The first stage is fibrin adhesion, in which fibrin acts as a kind of glue for the graft. Fibrin is whats in blood clots and it makes a mesh to stop bleeding.

Then there is plasma imbibition and it means that the grafted tissue is "absorbing" what it needs from the underlying area, and it is something temporary that happens in the first couple days until the graft is more established.

After this is the phase of inosculation and revascularization, and in this phase there is the growth of new blood vessels (neoangiogenesis is a big topic, but know that tissues that are devoid of a blood supply, ischemic tissues, stimulate the production of new vessels in order to remedy the situation). These new vessels enter the graft or connect to vascular channels in the graft (the graft tissue has its own vessels that were cut off when it was taken), and this process happens from day 2 to up to around a week.

Finally there is the remodelling phase, which is what it sounds like. There are some processes that continue happening over a week after the graft, like continued revascularization and fibrogenesis, which means that some special cells make connective fibers and some other materials that contribute to the extracellular environment which is very important for cells' normal function. This helps the graft to properly fit in to its new environment.