Abstract
Summary
The effects of deafferenting the hypophysiotrophic area were studied in lac-tating Sprague-Dawley rats to trace the pathway or pathways by which the suckling stimulus affects hypophyseal function. Postero-bilateral and antero-bilateral deafferentation was carried out in 10 rats by the procedure described by Halász and Pupp. In 2 rats deafferented postero-bilaterally, bilateral deafferentation was started 0.5 mm posteriorly, so that the lateral deafferentation was incomplete. The operated animals (with the exception of these 2 rats deafferented incompletely) failed to rear their pups. This failure is ascribed to the blockade of milk ejection since pups could obtain milk when the mother was injected with exogenous oxytocin. Severe diabetes insipidus was observed in 2 out of 3 animals deafferented antero-bilat-erally. Since only one of the 4 rats deafferented postero-bilaterally showed any diabetes insipidus, yet all showed loss of reflex discharge of oxytocin, the pathways of the latter mechanism to the hypophysiotrophic area must enter laterally, and they cannot be identical to the supra-optico-hypophyseal tract.
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