Observations on the intracranial carotid rete and the hypophysis in the mature female pig and sheep.

It is accepted that in the pig the intracranial carotid retia are connected across the midline by numerous arteries lying within the intercavernous sinus. The present study has demonstrated that these vascular elements fill the greater part of the very deep sella turcica, the cranial hypophysis occupying an almost suprasellar position. In the sheep the anastomosis between the carotid retia is limited to a few arteries crossing the midline posterior to the hypophysis, and the gland lies wholly within the sella turcica. It is suggested that the position of the cranial hypophysis in the mature female pig results from the inward and upward pressures exerted on the hypophysis by the carotid retia and their extensive interconnexions in this species.