الفهرس 
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Abstract
present study was undertaken to provide a comprehensive description prenatal development of the albino rat cochlea and the cochlear nuclei are the first synaptic interruption in the central auditory system. It was erformed to cover the hortage in the literature concerning the cellular tiation of the cochlear nuclei.
A total of 32 female albino rats were used in this study. The duration of egnancies were estimated and embryos were taken from the 10th day anon till full term. The prenatal development of the cochlea and nuclei were studied in sections stained with Hx.& E, cresyl fast
ajal silver stain and acetyl cholinesterase.
e 11th prenatal day, the otocyst had closed and became separated surface ectoderm. The cochlear duct appeared by the 12th prenatal n extension of the ventral aspect of the otocyst. It increased from a
In the 13th day to 2 and half coils by the 18th day.
udal wall of the cochlear duct was formed at first of undifferentiated of 5-6 layers of nuclei at the 12th day till the 16th day.
Ion of the hair cells appeared at the 17th prenatal day in the basal nded to the apical turn at full term. A small cavity appeared at the tunnel of Corti in the basal turn at the 19th day.