“…Following a series of studies characterizing PNs in various mammals including man (Brü ckner et al, 1993(Brü ckner et al, , 1996a(Brü ckner et al, ,b, 1998Ohyama and Ojima, 1997;Lander et al, 2002;Matthews et al, 2002;Szigeti et al, 2006), recent advances demonstrated the presence and described the distribution of PNs in chicken brain and showed a very fast matrix maturation after hatching (Morawski et al, 2009). The early appearance of perineuronal nets in the precocial birds brain was supposed to be due to the rapid establishment of neuronal morphology (Tö mbö l, 1988(Tö mbö l, ,1995 and function which is required for the immediate functional and behavioural performance of chicks (Corner and Bakhuis, 1969;Lippe, 1995;Rogers, 1993).…”