Perisomatic changes in the maturing hypoglossal nucleus after XXXX .

@entity128 @entity1897 @entity35 @entity21 @entity528 @entity130
The perisomatic retrograde reactions to @entity1897 during postnatal maturation were investigated by quantitative light and electron microscopy. The hypoglossal nerve was crushed, ligated or transected in 10 and 21 day postnatal (dpn) @entity35 . Only @entity130 was made in 7 dpn @entity35 . Survival periods ranged from 3 to 40 days postoperative (dpo). Normal and sham operated animals of corresponding ages served as controls. A remarkable, transient response of neuronal somata in the young (7-10 dpn) @entity35 , following all three types of @entity21 , was the formation of excrescences which engulfed neuronal processes: boutons, dendrites, small neurites and a few myelinated axons in adjacent neuropil. The somal engulfment was rarely evident after @entity128 to 21 dpn @entity35 . Bouton displacement from the somal surface, accompanied by glial incursion, followed each @entity128 but was less extensive and occurred later in the young @entity35 . There seemed to be no association in the amount of boutons displaced from neuronal somata with the @entity128 for any of the three experimental age groups. However, the rate and intensity of the perineuronal glial reaction were related to the severity of the @entity128 in the older (21 dpn) but not in the younger (7-10 dpn) @entity35 . Substantial loss of neurons occurred in the affected nucleus after each type of @entity130 to the young neurons. The degree of @entity528 was related to the age and the volume of axoplasm disrupted. Only nerve transection in 21 dpn @entity35 resulted in appreciable @entity528 . The responses of axotomized neurons, their afferent axon terminals and the surrounding glia are quantitatively and qualitatively different in the hypoglossal nucleus of @entity35 of increasing postnatal ages.
