BUTYRYLCHOLINESTERASE ACTIVITY IN THE DEVELOPING AUDITORY BRAIN-STEM,THE CHOROID-PLEXUS AND THE PITUITARY OF THE PERINATAL RAT

The butyrylcholinesterase activity in the vasculature of the brain, ch oroid plexus, and pituitary, was studied histochemically in rats durin g postnatal days 1, 7, 14,21 and 28. The brainstem auditory nuclei wer e used for comparison of vessels at different ages. We found intense b utyrylcholinesterase activity in all intraparenchymal blood vessels, e specially capillaries, in all ages. In the meningeal vessels, activity was especially prominent in 1 and 7 day old animals when the perineur al meninges was relatively thick. In the pituitary, reaction for the e nzyme was found in nonvascular elements, especially in the intermediat e and posterior lobes. Vessels of the choroid plexus were associated w ith punctate regions of butyrylcholinesterase activity. These results do not support the suggestion of a major role for butyrylcholinesteras e in the blood-brain barrier.