A micro-suture was a microscopic suture used to connect two separate things. The Borg used similarly designated microconnectors on their drones to connect exo-plating to their bodies. (VOY: "The Gift")
As evident in the script for "The Gift", the term "microconnectors" was originally described as "microsutures".
In 2374, when Seven of Nine's Human immune system began to assert itself on the recently disconnected drone, The Doctor noted that head armor plating was attached to her skull with over 3 million microconnectors. Due to her rapidly deteriorating condition he explained that he did not have time to remove them one by one, so he opted to surgically removed it by extracting a few layers of cranial tissue along with the armor. (VOY: "The Gift")
Around the same time that year, after Doctor Julian Bashir repaired the injured Keevan, he warned the Vorta to be careful because "Most of your insides are being held together with cellular micro-sutures and a lot of hope." (DS9: "Rocks and Shoals")
The following year, The Doctor discovered, among a number of salvaged Borg components, a servo-armature from a medical repair drone, which he described as "a laser scalpel, biomolecular scanner, micro-suture, all rolled into one instrument." (VOY: "Dark Frontier")