Early morphological changes following gamma irradiation. A comparison of human pituitary tumours and human acoustic neurinomas (schwannomas).

The in vitro system was used to study early ultrastructural effects following gamma irradiation of human pituitary adenomas and neurinomas with 30 and 70 Gy single doses, respectively. The acoustic neurinoma cells showed a large number of intracellular myelin figures and vesiculation of cytoplasm. The pituitary tumour cells showed vacuolization of cytoplasm and cell organelles. Occasionally, electron-dense cytoplasmic inclusion bodies with a fibrillar substructure occurred. The differences between the two types of tumours in irradiation-induced morphological changes may indicate differences in their biochemical structure and metabolic activities. The morphological findings after irradiation of specimens from all four neurinomas were rather similar after the same length of time but the structural alterations of pituitary cells differed considerably between individual tumours. The 70 Gy dose caused more rapidly-occurring morphological alterations than the 30 Gy single dose.