Morphological development of the brain stem reticular core in prenatally undernourished rats.

The development of brain stem reticular core neurons in prenatally undernourished rats was investigated using the Golgi technique to determine the effect of immediate postnatal nutritional rehabilitation. Quantitative measurements of dendritic extent of branching and of cell size were compared in experimental and control neurons. An assessment of developmental dendritic status was achieved by counting numbers of dendritic protospines and varicosities on proximal and distal segments of dendrite. The protein and DNA content of the brain stem was also examined. The deficit of brain stem cell number at birth was rapidly restored by 11 days of age as was the delay of dendritic development. The number of dendritic protospines was comparable to control levels by 20 days but dendritic varicosities were more numerous on proximal segments. The dendritic extent increased during this period with rehabilitation though not as greatly as in control cells. The pattern of dendritic branching and size of somata were restored. Cell replication with rehabilitation probably represents a return of glial numbers which may impede distal dendritic growth of reticular core dendrites. Proximal growth is enhanced and the afferent supply to the reticular core may be increased during this time.