RT Journal Article SR Electronic T1 Visual cortex development in the ferret. I. Genesis and migration of visual cortical neurons JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 1242 OP 1253 DO 10.1523/JNEUROSCI.09-04-01242.1989 VO 9 IS 4 A1 Jackson, CA A1 Peduzzi, JD A1 Hickey, TL YR 1989 UL http://www.jneurosci.org/content/9/4/1242.abstract AB The production of ferret visual cortical neurons was studied using 3H- thymidine autoradiography. The genesis of cortical neurons begins on or slightly before embryonic day 20 (E20) of the 41 d gestational period, continues postnatally until 2 weeks after birth (P14), and follows an inside-out radial gradient with neurons for the deeper cortical layers being generated before those for the superficial layers. Layer I neurons are generated both early (E20-E30) and late (P1-P14) in the period of cortical neurogenesis and, thus, provide at least a partial exception to the inside-out gradient of cortical neurogenesis. Tangential gradients of cortical neurogenesis extend across areas 17 and 18 in both the anterior-to-posterior and lateral-to-medial directions. Neither of these gradients bears a meaningful relationship to the cortical representation of the visual field. Most infragranular and granular layer neurons are generated prenatally, while most supragranular layer neurons are produced postnatally. Neurons destined for a given layer are produced over a period of several days, and the neurons generated on any given day contribute to the formation of 2 or more cortical layers. In general, prenatally generated neurons complete their migration in 1 week or less, while most postnatally generated neurons require approximately 2 weeks to complete their migration.