Formation of the peripheral-central transitional zone in the postnatal mouse cochlear nerve.

Abstract

OBJECTIVES: Determine the formation of peripheral and central nervous system (CNS and PNS) transitional zone (PCTZ) along the postnatal mouse cochlear nerve. STUDY DESIGN: Prospective, basic science. SETTING: Research laboratory. SUBJECTS AND METHODS: A novel cryosection model of cochlea-cochlear nerve-brainstem was used in this study. The sections were harvested from a total of 45 mice in 9 groups of postnatal-day-0 to postnatal-day-60 mice (n = 5). Differential interference contrast microscopy and immunofluorescence were used to study the formation of PCTZ along the cochlear nerve of the postnatal mouse. RESULTS: The CNS tissue extended peripherally along the cochlear nerve from postnatal-day-0 to postnatal-day-7 and then stably located at the level of the spiral lamina of the basal cochlear turn. The PCTZ reached a mature pattern along the cochlear nerve after postnatal-day-7. A long segment of the CNS tissue extended along the cochlear nerve in the postnatal mouse. CONCLUSION: In the early postnatal days, the PCTZ extended peripherally toward the cochlea and obtains a mature pattern along the neonatal mouse cochlear nerve.