PARS-DISTALIS CELL QUANTIFICATION IN NORMAL ADULT MALE AND FEMALE RATS

Cell types in the pars distalis of normal young adult male and female rats were analyzed with respect to their percentages and the relative volumes they occupy. In male rats the percentages of the cell types were prolactin 49.80, GH [growth hormone] 22.67, LH [luteinizing hormone] 5.04, FSH 4.22, ACTH 2.93 and TSH 2.09. The volume densities were prolactin 20.48, GH 20.95, LH 7.34, FSH 6.73, ACTH 3.75 and TSH 3.19. In female rats the percentages of the cell types were prolactin 52.40, GH 20.30, LH 5.89, FSH 4.06, ACTH 2.53, TSH 2.40 and the volume densities were prolactin 28.09, GH 20.86, LH 8.11, FSH 5.46, ACTH 3.49 and TSH 2.91. The percentages of pars distalis cells which did not stain with the antisera to the 6 classical hormones were 17.47 in male and 16.48 in female rats. The results suggest that in both sexes the number (N) of prolactin cells > N of GH cells > N of gonadotrophs > N of TSH or ACTH cells; the percentage of each cell type was similar in both sexes; the volume density (Vv)of prolactin cells was greater than the Vv of GH cells in female but not in male rats and in both sexes the Vv of GH cells > the Vv of gonadotrophs > the Vv of TSH or ACTH cells; in both sexes the volume (V) of prolactin cells < the V of GH cells < the V of gonadotrophs, the V of TSH cells or the V of ACTH cells; the V of prolactin cells was greater in female than in male rats; and approximately 17% of the cells in the pars distalis of both sexes did not contain immunoreactive prolactin, GH, LH, FSH, TSH or ACTH.