This thesis presents research that aims at improving the understanding of spin-related transport in InAs nanodevices. The decisive components of rather complex spin-filter cascades, namely quantum point contacts and quantum wires, have been studied. All integer and spin-resolved half-integer plateaus of the conductance quantization up to the highest occupied transport mode have been resolved in side- and top-gated devices. Also some indication of the anomalies, that are known from GaAs and SiGe quantum point contacts, have been observed in InAs. In addition, out-of-plane magnetic fields enhance the pronunciation of the conductance plateaus. By the application of a single top-gate electrode, measurements on spin-filter cascades are easier and the device can be downscaled to reach the ballistic transport regime more reliably. Clear evidence for conductance quantization has been found in top-gated spin-filter cascades in good agreement with the results obtained from quantum point contacts. In in-plane magnetic fields even some evidence for the so-called zitterbewegung has been found.