“…Lesions have been produced effectively either by long single freezes of up to 15 minutes, or many more rapid cycles of five minutes (Giffin et al 1965, Grossart 1972, Rand 1967). The adenohypophysis is resistant to many physical insults, requiring for example 300 000 rads to achieve ablation, and this is reflected in the profound refrigeration required to destroy it.…”