In V2 of many species, it is impossible to recognize two classes of CO stripes: thick and thin. In other species (e.g. squirrel monkeys), they can always be differentiated clearly. Remarkably, even within a species, expression of V2 stripes can be whimsical. In some macaques, thick and thin stripes are obvious, whereas in other macaques, they cannot be distinguished. Failure to visualize thin and thick stripes in some macaques is not an artefact of poor histology. This section shows an example of abysmal histology with uneven section thickness, chatter and tissue cracking, yet a tripartite pattern of CO stripes is still obvious in V2. After flatmounting and staining for CO in area V2 of more than 20 macaques, we have concluded that the variation in stripe expression is real.