An experimental study and review of the literature on the oriented crystallization of high polymers was made to develop an understanding of how ``row‐nucleated'' or shishkebab microstructures and the fibrillar links between lamellar crystals may be formed. A new mechanism is proposed for the formation of the fiber nuclei in flowing melts, based on the mechanical alignment and extension of molecules that are entangled with, and extend between, two or more rotating clusters in the melt. Similar alignment of molecules can occur when entangled clusters are pulled to different lamellar crystals during crystallization, producing intercrystallic links.