Significance of Vacuolated Neurones in the Medulla of Sheep affected with Scrapie

Abstract

VACUOLATED neurones in the medulla have been considered for quite a long time by several workers as the only constant microscopic lesion in sheep affected with scrapie. On the other hand, Holman and Pattison¹, although finding vacuoles in all their clinical cases of scrapie, reported vacuoles in the medulla in a small proportion of non-scrapie sheep (in 5 out of 98 animals). Zlotnik and Rennie² examined material from 57 healthy sheep of various ages using serial sections from three levels of the medulla, and demonstrated vacuoles in about 73 per cent of sheep, mainly of the Cheviot breed. Bosan-quet, Daniel and Parry³ found only occasional vacuoles in the large neurones of the medulla of scrapied animals, but have seen similar vacuoles in normal sheep. Pattison⁴ has discovered the incidence of vacuolated neurones in goats in which scrapie had been induced experimentally. According to him, 2,279 vacuoles were present in ninety-four sections, from medullas of 16 scrapie goats, whereas only 8 vacuoles could be found in 592 sections from medullas of 16 healthy goats.