Effects of prevention of afferentation of the development of the chick optic lobe

Abstract

[411][412][413] 19711.-The effects of unilateral extirpation of the right optic cup of the three-day incubated chick embryo upon the rate of synthesis and the stability of DNA in the non-innervated optic lobe, have been studied. This surgical procedure prevents innervation of the optic lobe contralateral to the removed eye, while the other optic lobe is normally innervated by retinal ganglion cells of the remaining eye. At the 20th day of incubation, the DNA content of the non-innervated lobe was below that of the paired lobe receiving normal innervation. This deficiency of cell number was caused by two events; death of an excess number of neurons formed early in embryogenesis and a reduced rate of glial proliferation in the later stages of incubation. Non-innervationEnucleation Chick embryo

Rapid onset of neuronal death induced by blockade of either axoplasmic transport or action potentials in afferent fibers during brain development

“…Although it is well known that deafferentation causes developing neurons to die, there was little previous evidence to suggest that the induction of cell death would be rapid. In most cases, the earliest effects of deafferentation have simply not been investigated (for review, see Oppenheim,199 l), or an arbitrary delay has been introduced by eliminating the afferents several days before their time of synapse formation (e.g., Bondy et al, 1978;Okado and Oppenheim, 1984;Clarke, 1985). The minority of experiments that did address the timing mostly indicated that cell death would occur several days after deafferentation (for review, see Cowan, 1970).…”

Effects of Enucleation on High‐Affinity Binding Sites in Chick Optic Tecta

“…Characterizations of the morphological consequences of this procedure in this system have been made for both early noninnervation, where normal growth and cytoarchitecture is interrupted (Kelly and Cowan, 1972;Mathers and Ostrach, 1979), and for later deafferentation, where effects similar but quantitatively less severe than noninnervation were observed (Kelly and Cowan, 1972). Biochemical changes resulting from enucleation have also been described for both noninnervation (Bondy et al, 1977(Bondy et al, , 1978 and for deafferentation (Marchisio, 1969;Carton and Appel, 1974;Bondy et al, 1977).…”