DETERMINATION OF STEREOTAXIC COORDINATES FOR THE HIPPOCAMPUS IN THE DOMESTIC PIG

In this study a stereotaxic instrument and a stereotaxic procedure bas ed on external skull structures, to be used in prepubertal male Landra ce pigs weighing less than 30 kg, is described. The instrument represe nts an adaptation of the apparatus designed by Marcilloux et al., Brai n Res Bull 1989,22.591-597, but we have modified the instrument for st ereotaxic procedures based on external skull structures, instead of in tracerebral structures necessitating ventriculography (Marcilloux et a l., Brain Res Bull 1989;22:591-597). For this reason the U-shaped fram e and the ear-bar supports have been changed allowing the three-dimens ional placement of the ear-bars into the oblique auditory canals. Firm fixation of the skulls of pigs weighing less than 30 kg, was furtherm ore secured with modified infraorbital ridges and hard palate pieces. Measurements of distances between external skull structures in animals of the same sex, age and weight showed a negligible variation, thus e nabling definition of the horizontal, frontal and sagittal zero planes using external skull structures alone. Stereotaxic coordinates for th e hippocampal region of male Landrace pigs weighing 10 kg were then pr ovided and the coordinates from two different levels of the hippocampa l region are presented in the text. The reliability of the stereotaxic instrument was finally secured by intrahippocampal injections of ink at predetermined coordinates. (C) 1998 Elsevier Science B.V. All right s reserved.