Development and regression of cochlear blood vessels in fetal and newborn mice

Various strains of mice have been used for hearing research, but there have been few reports regarding the cochlear vasculature in mice. In this study , the development of the cochlear vasculature was investigated in C57BL/6 m ice from day 15 of gestation to day 15 after birth, and mature vessels were also observed in 3-month-old mice. Both India ink injection and the resin casting method were used. On gestational day 17, spiral vessels of the basi lar membrane were developing and were elaborating communicating branches th at ran toward the external wall and the spiral lamina. On day 18, the spira l vessels showed the largest diameter of all vessels in the cochlea, but th ese vessels subsequently regressed and finally disappeared by day 14 after birth. The external wall vessels formed a single-layer capillary network at birth and subsequently divided into two layers, which became the vessels o f the stria vascularis and the spiral ligament vessels. This process occurr ed progressively from the basal turn toward the apical turn between days 5 and 8 after birth. A general tendency for the cochlear vasculature to matur e from the basal turn towards the apex was observed. (C) 2000 Elsevier Scie nce B.V. All rights reserved.