membranes may not have a thickness compatible with these dimensions and can be skived planed slit or microtomed to meet a desired dimension this process also offers the surgeon the control options for the type of tissue to be used to form the aty in most cases the membrane and tissues that can be harvested have a multi layer structure it may be desirable to use only some of these layers and not use others in the formation of aty other cutting or fiber formation methods such a straight line slitting laser cutting water jet cutting or helical slitting are all candidate methods for formation of aty the aty need not be monofilament in nature it can be multifilament or it can be multifilament with twist as in a staple fiber formation which will be readily understood by those in the textile arts yarn sizes and vessel wall thickness must be related for very small structures such as 1 or 2 mm diameter veins the wall thickness must be equally thin in this case the available autologous tissue membrane may require not only thin sectioning into tapes or strips but also reduction in thickness this processing can be done both before and after the initial sectioning has been done and can include both mechanical rolling or drawing and cutting or skiving techniques the imperfections in the aty in very thin.