[Effect of histological technics on the volume and weight of various brain structures of rats at the early stages of life].

The aim of the studies was to elaborate technical procedure of material preparation for quantitative studies and determination of correction coefficients of morphometric parameters in dependence on histological procedures. Moreover, volume changes of the rat substantia nigra and striatum (structures degenerating in Parkinson's disease) during the first half year of life were estimated. As fixatives 4 and 8% formaldehyde in 4 and 20 degrees C were used. Irrespective of applied variant of fixation formaldehyde produced during first 48 hrs rapid increase of the brain weight and volume up to 52% of that of the fresh brain, which was followed by slow decrease of brain weight of about 1-3%/24 hrs. The most pronounced changes caused 4% formaldehyde in 20 degrees C. The best conditions for morphometric studies were obtained with the use of 8% formaldehyde in 20 degrees C. Dehydration in ethyl alcohol produced violent decrease of brain volume and weight (from 32% up to 39% of the fresh brain weight). Clearing in methyl bensoesane increases again the brain weight by a few percentage. The obtained results make possible to estimate error size in morphometric studies conducted on the formaldehyde-fixed material. It was stated also that the above histological procedure causes more pronounced changes in fetal rat brain and in brain of 1-2-day-old rats. Stabilization of changes caused by histological procedure is achieved between first and sixth months of rat life.