Extreme points in the space of ucp maps

Question

Suppose $M$ and $N$ are $\mathrm{II}_1$ factors. Let $\tau\mathrm{UCP}(M,N)$ be the convex space of trace-preserving UCP maps from $M$ to $N$, equipped with the topology of pointwise weak* convergence. One sees that the space is compact, so by Krein-Milman, it is the closed convex hall of its extreme points. What are these extreme points? Is the set of extreme points closed? It is clear that it contains *-homomorphisms, so in particular what are pointwise weak* limits of *-homomorphisms?