Oesophageal striated muscle arrangement and histochemical fibre types in guinea-pig, marmoset, macaque and man.

The muscularis externa of the oesophagus was examined histologically and histochemically in the guinea-pig, marmoset, and man. It was found that the transition from striated muscle to smooth occurred more gradually and at a more proximal level in the primates than in the guinea-pig. In addition, minor differences in fibre lay-out were observed between the four species examined. Guinea-pig oesophageal striated muscle was all found to be of one type, 'fast twitch' oxidative and glycolytic. The marmoset oesophageal muscle, also unitypical, was 'slow twitch' and oxidative. Both the macaque and man each revealed two types: 'slow twitch' oxidative glycolytic and 'fast twitch' oxidative glycolytic, and concluded that these differences represent species variation.