Cytoarchitecture of chicken Wulst: a Golgi study on cell types and their maturation after hatching.

In the Golgi preparation of visual Wulst of chicken four types of projection neurons were found: type 1a, 1b, 1c, and 1d neurons, which are distinguished on the basis of their dendritic ramification pattern and especially on the density of the dendritic spines. Type 1a has large dendritic tree with moderately dense spiny dendrites. Type 1b has very dense spiny dendrites. Type 1c is a small neuron with moderately dense spiny dendrites. Type 1d is a star-pyramid-like neuron with a short, bifurcating apical dendrite. The final dendritic pattern and spine density of projection neurons was found to develop at the end of the first month. In the Wulst short axon cells (interneurons-INs) of different types occur: large, medium-sized and small INs can be observed. Their axon-arborizations are significantly different from each other. Some of them are GABA-immuno-positive neurons, which are very probably inhibitory interneurons. Stellate-like neurons also occur in IHA and HIS. These neurons have sparsely spiny dendrites and locally arborizing axons.