Neural projections of the preoptic-suprachiasmatic region to the median eminence in the rat: a quantitative autoradiographic study.
The possibility of a preferential distribution of projections from the preoptic-suprachiasmatic region (POA-Sch) to the median eminence in the male rat was studied using autoradiographic and computer procedures. A cocktail of [3H]leucine-[3H]proline was injected into the POA-Sch. Animals were killed after either 1, 4, or 24 h of incorporation time (IT). The number of silver grains per 25-micron square was counted throughout the median eminence. Squares with silver grain densities at or above the 75 percentile of the population for any given IT group were labeled as "concentrating areas." The distribution of these concentrating areas in median eminence tissue was analyzed utilizing univariate procedures. Visual inspection of the distribution of silver grain densities in a rostrocaudal fashion indicated the likelihood of uneven distribution; however, these differences were not statistically significant. In the dorsoventral plane, results indicated that the highest silver grain density was at 50 to 75 micron from the floor of the 3rd ventricle. Such distribution was apparent both ipsi- and contralateral to the injection site, but was greater on the ipsilateral side.
D000818:Animals; D007032:Hypothalamus, Anterior / Q000033:anatomy & histology*; D008297:Male; D008473:Median Eminence / Q000033:anatomy & histology*; D009434:Neural Pathways / Q000033:anatomy & histology; D011301:Preoptic Area / Q000033:anatomy & histology*; D051381:Rats; D011919:Rats, Inbred Strains