Glycine-immunoreactive synapses in the central nucleus of the inferior colliculus. An electron microscopic study in the cat.

It has been known that the inferior colliculus contains many glycinergic fibers of both intrinsic and extrinsic nature. In the present study, glycine-immunoreactive (Gly-ir) synapses were examined in the central nucleus of the inferior colliculus in the cat. About half of 891 axondendritic synapses that were identified in the present study were Gly-ir. In 75% of these Gly-ir synapses, synaptic axon terminals contained pleomorphic or flattened synaptic vesicles and made symmetric synapses, while in 25% of Gly-ir synapses, synaptic axon terminals were filled with spherical synaptic vesicles and formed asymmetric synapses. Thus, Gly-immunoreactivity was detected in axodendritic synapses that formed both Gray's type I and Gray's type II synapses.