Intercellular communication through gap junctions plays an important role in a variety of cellular processes including homeostasis, morphogenesis, cell differentiation and growth control. Interestingly, reduction or alteration in the levels or types of connexin expressed in a given cell type has been found to correlate with tumor progression and metastasis. The murine Cx36 gene encodes a protein of 321 amino acids most homologous to connexin 35. Based on the presence of an intron within its coding region the Cx36 gene is suggested to form a new delta subclass of murine connexin genes. Specific cell types in the brain express specific types of connexins; expression and expression patterns coincide with tissue compartmentalization and function. These compartments change during development. Cx36 is the first gap junction protein expressed predominantly in neuronal cells of the mammalian central nervous system. It is highly expressed in adult retina and is present in neurons of the inferior olive, the olfactory bulb, the CA3/CA4 hippocampal subfields and several brain-stem nuclei. Cx36 mRNA expression in the brain gradually increases during fetal development until day seven post-partum when it’s expression begins to decline. Biophysical measurements of gap junction channels formed by transfected and endogenous Cx36 indicate that they possess unique properties well-suited for mediating flexible electrical and biochemical interactions between neurons.