Ultrastructure of lipid-containing cells of the anterior pituitary gland of the domestic chicken, Gallus domesticus.

A combination of light and electron microscopy techniques was applied to characterize a luteinizing hormone (LH)-gonadotroph-like cell in the anterior pituitary gland of the adult domestic chicken. This cell type (mean +/- sem, 91 +/- 8 microns2) was larger than typical LH-gonadotrophs (71 +/- 5 microns2, p < 0.01) and seen in pituitary glands from adult males but not those from adult females of the same age. The ultrastructural features of these cells were similar to typical LH-gonadotrophs in the same section, except for the presence of large (1,126 +/- 77 nm diameter), round, or polymorphic electron-dense inclusions (14 +/- 3 per cell) in the cisternae of the endoplasmic reticulum. When resin sections of anterior pituitary gland were stained with the vapours from the fixative osmium tetroxide and a solution of potassium ferricyanide, inclusions were found that appeared to be lipid in nature and were circumscribed by the cisternal membranes of the endoplasmic reticulum. These lipid inclusions were associated occasionally with acid phosphatase and lysosome-like bodies. The cellular pigment, lipofuscin, considered to be a marker of aging, was absent from the anterior pituitary glands from these adult chickens. These observations suggest that the appearance of lipid in LH-gonadotrophs is unlikely to be age-related and an alternative explanation is discussed in relation to a sex difference in the LH response of adult chickens to gonadotrophin-releasing hormone (GnRH).