Heterogeneity of pituitary gonadotrope cells in male rats.
Mammalian gonadotrope (Gn-) cells producing FSH and LH show great variability in their cytological characteristics. To gain a closer view of the corresponding phenotypes, Gn-cells of male rats were investigated by various methods including immunocytochemistry on serial semithin sections, quantitative immunocytochemistry, three-dimensional reconstructions, sequential semithin-/thin-section technique, routine electron microscopy, and immuno-electron microscopy. Gn-cells were immunostained with FSH and LH antisera and with antibodies raised against synthetic N- and C-terminal sequences of chromogranin A (CgA) and secretogranin II (SgII), and four phenotypes of Gn-cells could be identified. The great majority of Gn-cells were densely immunoreactive for both gonadotropins and both chromogranins and accordingly classified as "typical" gonadotropes; a second type was less immunoreactive for LH and therefore was termed "LH-poor". The two remaining phenotypes showed ultrastructures suggesting an increased synthetic activity. One of them was characterized as a "FSH/CgA-poor" gonadotrope. The other, also poor in CgA, morphologically corresponded to "signet-ring" cells previously known only in gonadectomized animals. The two types of secretory granules present in male rat Gn-cells showed a strict segregation of chromogranin immunoreactivities: CgA was confined to the large, less opaque granules, whereas SgII, to the small, electron-dense granules. Consequently the two "CgA-poor" Gn-cell subtypes exhibited only a very few large-sized secretory granules. A correlation was suggested between high cellular activity and a decrease in CgA in Gn-cells. The reasons for the morphological and functional heterogeneity of Gn-cells remain enigmatic. Presumably, they either differ in the susceptibility for GnRH and testosterone or are differently regulated by paracrine factors.
Jeziorowski
T
T
Department of Anatomy I, Hannover Medical School, Germany.
Watanabe
T
T
Bargsten
G
G
Grube
D
D
D000818:Animals; D053379:Chromogranin A; D002864:Chromogranins / Q000032:analysis*; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D003720:Densitometry; D005640:Follicle Stimulating Hormone / Q000032:analysis*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D007986:Luteinizing Hormone / Q000032:analysis*; D008297:Male; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D010903:Pituitary Gland, Anterior / Q000737:chemistry / Q000166:cytology* / Q000648:ultrastructure; D011506:Proteins / Q000032:analysis*; D051381:Rats; D011917:Rats, Inbred Lew
D053379:Chromogranin A; D002864:Chromogranins; D011506:Proteins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone