Hormonal regulation of the shape of identified motoneurons in the moth XXXX .

@entity4079 @entity2338 @entity527 @entity8827 @entity134
Motoneurons MN-1 and MN-3 in the moth @entity4079 go through 3 distinct phases during postembryonic life. During larval life their neuritic fields show allometric growth in concert with larval growth. @entity527 are then lost during the larval-pupal transition, which is followed by the outgrowth of adult-specific neurites during adult development. In MN-1, the adult-specific arbor typically results from the outgrowth of neurites ipsilateral to the cell body. However, in a small percentage of cells, ipsilateral branches are not present and contralateral branches extend across the midline to fill the vacant space. This altered form of MN-1 is thought to result from the early failure of ipsilateral neurite extension. The @entity134 hormones, the @entity8827 , are responsible for the outgrowth of adult neurites. The onset of the latter is correlated with the @entity8827 increase that promotes adult differentiation and does not occur under conditions such as diapause, in which the normal @entity134 rise is absent. Artificial replacement of @entity8827 , however, induces the adult-specific growth. This action of @entity8827 to cause a change in neuronal form requires the absence of @entity2338 ( @entity2338 ). Application of @entity2338 mimics prior to the onset of the program of adult outgrowth blocks this outgrowth. MN-1 and MN-3 show different times of @entity2338 sensitivity, which appear to be correlated with different times of neurite outgrowth. It is concluded that the role of @entity2338 is to maintain the status quo of central neurons and prevent changes in form in response to @entity8827 . In the absence of @entity2338 , the @entity8827 can then exert morphogenetic changes, but the nature of these actions, neurite outgrowth or regression, is likely a function of the developmental history of the cell.
