Timing of neuronal intermediate filament proteins expression in the mouse vomeronasal organ during pre- and postnatal...

Several types of intermediate filament proteins are expressed in developing and mature neurons; they cooperate with other cytoskeletal components to sustain neuronal function from early neurogenesis onward. In this work the timing of expression of nestin, peripherin, internexin, and the neuronal intermediate filament triplet [polypeptide subunits of low (NF-L), medium (NF-M), and high (NF-H) molecular weight] was investigated in the developing fetal and postnatal mouse vomeronasal organ (VNO) by means of immunohistochemistry. The results show that the sequence of expression of intermediate filament proteins is internexin, nestin, and NF-M in the developing vomeronasal sensory epithelium; internexin, peripherin, and NF-M in the developing vomeronasal nerve; and nestin, internexin and peripherin, NF-L, and NF-M in the nerve supply to accessory structures of the VNO. At sexual maturity (2 months) NF-M is only expressed in vomeronasal neurons and NF-M, NF-L and peripherin are expressed in extrinsic nerves supplying VNO structures. The differential distribution of intermediate filament proteins in the vomeronasal sensory epithelium and nerve is discussed in terms of the cell types present therein. It is concluded that several intermediate filament proteins are sequentially expressed during intrauterine development of the VNO neural structures in a different pattern according to the different components of the VNO.