A New Tissue-Slicing Method for the Study of Function and Position of Somatotrophs Contained within the Male Rat Pituitary Gland*

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Abstract
A tissue-slicing method has been developed for obtaining quantitative information relative to the function and distribution of somatotrophs in the individual pituitary of the male rat. The adenohypophysis was cut along midtransverse, coronal, and sagittal planes, dividing the gland into eight distinct slices. Basal (unstimulated) GH release was measured from sections placed in gyrotory incubation for three consecutive periods (20 min each). Response to rat hypothalamic GH-releasing hormone (rhGHRH) was studied in slices placed in perifusion and in dispersed cells placed in static incubation. Tissues and cells were analyzed by light and electron microscopy and flow cytometry. Cells retained good morphological integrity and viability (>85%) after incubation (1 h) or perifusion (5 h). Somatotrophs were evenly distributed dorsoventrally; mean values for dorsal and ventral sections were 45.3 .+-. 2.5% and 38.9 .+-. 1.9%, respectively. Differential basal GH release was observed after the first gyrotory incubation period; values differed by as much as 3-fold. These differences became less apparent with subsequent incubations. Pituitary slices in perifusion showed a differential response to rhGHRH. For some sections GH release increased up to 2-fold; in other sections the response was either negligible or absent. Dissociated cells from sections also showed differential response to rhGHRH; increases ranged from 160-250% above unstimulated values. These studies demonstrate that tissue slicing is a useful method for investigating pituitary cell function in vitro. The correlation between function and position suggests that heterogeneity of somatotrophs is related in part to their location in the gland.