The changes of enzymatic activity in blood vessel walls of rat brain during extrauterine development. Histophotometric studies.

The investigations of acylohydrolase acylocholine (cholinesterase) enzymatic activity in the brain vessels walls were performed during extrauterine ontogenic development on 3rd, 7th, 14th, 21st, 28th, 40th and 60th days of life and in the 18 months old rats using Koelle method. Objective evaluation of histoenzymatic reaction intensity is rather difficult because of subjective factors and technical problems. Therefore, our estimations were performed by the use of microscopic unit "Morphoquant" produced by CARL ZEISS Jena factory and coupled with a KSR 4100 ROBOTRON computer. The measurements on 50 fields from parietal cortex or callosal corpus were executed using white light. The area of a single measuring field was 4,200 micron2. The results of measurements were expressed as the percentage of the measured field area occupated by blood vessels with positive ChE reaction in their walls. The results indicate that the amount of blood vessels with positive ChE reaction during the whole postnatal development is increasing. In particular, a very intense increase in the amount of vessels with ChE reaction take place between 7th to 14th days of extrauterine life. In the white matter of callosal corpus a very strong increase in the blood vessels amount with positive ChE reaction is visible between 21st and 28th days of life. In the brains of 18 months old rats a decrease in the positive blood vessels amount was noted. When compared to the parietal cortex, this decrease was higher in corpus callosum. From 40th day of life the amount of blood vessels with positive histoenzymatic reaction for ChE was higher in the grey matter than in the white matter.