We consider multicell multiuser MIMO systems with a very large numberof antennas at the base station. We assume that the channel is estimated by using uplink training sequences, and we consider a physical channel model where the angular domain is separated into a finite number of directions. We analyze the so-called pilot contamination effect discovered in previous work, and show that this effect persists under the finite-dimensional channel model that we consider.  We further derive closed-form bounds on the achievable rate of uplink data transmission with maximum-ratio combining, for a finite and an infinite number of base station antennas.