Regional distribution and ultrastructural characteristics of growth hormone - Secreting (GH) cells in the Adenohypophysis of Tokara goat

The adenohypophysial GH cells in Tokara goats were examined by light and electron microscopic immunocytochemistry. The immunoreactive GH cells distributed throughout the Pars distalis except for Zona tuberalis (ZT) and were recognized on a half of all secretory cells in the region in both sexes. The percentage area of GH immunopositive granules were 19.2% in male and 22.7% in female in that region. GH cell had a spherical, oval or irregular shaped nucleus, round or rod-like mitochondria, a lot of secretory granules, jaxtanuclear Golgi apparatus and rough endoplasmic reticulum running among granules. The secretory granules varied in size from cell to cell. Their average diameters were 329±15nm in male and 350± 15nm in female. More than 90% of GH cells had the granules of 250 to 400nm in the mean diameter in both sexes. Sex differences in the morphological features of GH cells were not recognized. By the comparison of the granule size with those of the other reports, it was clarified that Tokara goats showed rather small size in domestic ruminants.