ANTERIOR PITUITARY NECROSIS. INFARCTION OF THE PARS DISTALIS PRODUCED EXPERIMENTALLY IN THE RAT

¹ The Nuffield Institute for Medical Research, University of Oxford, and the Departments of Neurology, Neurosurgery and Pathology, Radcliffe Infirmary, Oxford

1. Infarction of the anterior lobe (pars distalis) of the pituitary gland was produced in rats by arresting the blood flow in the hypophysial portal vessels in the pituitary stalk. These vessels were occluded by the application of a fine cautery. The necrosis was of variable extent and occurred in the central part of the anterior lobe; the lateral, dorsal and caudal regions of this lobe remained healthy, as did also the neural lobe (pars infundibularis).

2. A study was also made of the vascular anatomy of the pituitary gland in normal rats. This showed that the part of the anterior lobe which became infarcted is the territory supplied by hypophysial portal vessels which drain the median eminence and run down the ventral aspect of the stalk, i.e. the vessels which had been occluded by cauterization. The regions of the anterior lobe which remained healthy are territories supplied by hypophysial portal vessels which had not been interfered with, in particular the group of portal vessels which, in the rat, drain part of the neural lobe. As in man, the sinusoids of the rat's anterior lobe receive no arterial blood.

3. The experiments support the view that the lesion seen in the human condition of "post-partum necrosis of the anterior pituitary" is due to a severe impairment of the circulation in the vessels of the hypophysial stalk and lower infundibular stem, which in man provide the anterior lobe of the pituitary gland with its sole blood supply.

Note:

We should like to thank Mr. J. H. Charles for help with the experiments and for looking after the animals, and Miss P. A. Alderton for cutting and staining the sections.