Cytology of a chromophobe pituitary adenoma. A case report

A pituitary tumor with suprasellar and extrasellar extension was investigated by means of the squash-smear cytologic technique. The dominant cell type was large, round to oval cells, with pale-staining, finely granular cytoplasm. The nuclei of these cells often contained single or multiple inclusions of uncertain nature. There also were cells with eosinophilic cytoplasm, usually collected in small nests. Hyperchromatic "naked" nuclei, in various shapes, were immersed in a homogeneous, faintly staining ground substance. Mitotic figures were detected easily. Cytology of these combined cell types allowed the intraoperative diagnosis of a rather pleomorphic pituitary adenoma.     

Regulation of gonadotropin secretion in the anterior pituitary

Studies on the regulation of gonadotropin secretion in dissociated pituitary cell cultures are described. Initial studies employing a ferritin-labelled analogue of gonadotropin hormone releasing hormone (GnRH) to localize its receptor sites on the gonadotropin cell surface that while these receptor sites initially have a random monodisperse distribution, binding of the ligand causes coarse aggregation and internalization of the GnRH receptor. These events are not due to the multivalency of the ligand and probably reflect redistributive events in vivo. By using an octapeptide analogue GnRH that binds to the GnRH receptor but lacks gonadotropin releasing activity in conjunction with sequence-specific antisera it is shown that antibodies that bind the octapeptide can induce the octapeptide to release gonadotropin. These data suggest that receptor aggregation is important in GnRH stimulation. Finally immunocytochemical studies are described in which golg-protein-A-antibody complexes are used to identify gonadotropins on ultrathin frozen sections of porcine pituitary cells. These studies indicate that in porcine gonadotropin cells the majority of the secretory granules contain both luteinizing hormone and follicle-stimulating hormone.     

Transformation of arachidonic acid in the rat anterior pituitary

Rat anterior pituitaries were incubated with [1-¹⁴C]-arachidonic acid. The metabolites were purified by reversed-phase high pressure liquid chromatography. Conclusive identification of the compounds was performed by gas chromatography-mass spectrometry. The major metabolite of arachidonic acid was the 12-hydroxy-5,8,10,14-icosatetraenoic acid (0.1% of added radioactivity). Smaller amounts of 12-hydroxy-5,8,10-heptadecatrienoic acid and of 15-hydroxy-5,8,11,13-icosatetraenoic acid (0.01% of added radio-activity) were also isolated. Trace amounts of prostaglandins E₂, D₂ and F₂α were detected.     

The prolactin and growth-hormone producing cells of the guinea-pig pituitary

Summary Different immunohistochemical techniques were used to identify the prolactin and growth hormone producing cells (STH cells) in the pituitary of normal guinea pigs at the ultrastructural level.Prolactin cells revealed two main aspects: 1. Cells with granules from 2500 to 3500 Å in diameter some of which are irregularly shaped. These granulations are scattered throughout the whole cytoplasm. The rough endoplasmic reticulum is well developed and organized in parallel lamellae. 2. In cells of the second type the granules are less numerous and smaller in diameter (1800 to 2500 Å) and the rough endoplasmic reticulum is less well developed.The cytoplasm of the STH cells contains many more round granules (generally grouped) which also range from 2500 to 3500 Å in diameter.The prolactin molecules and the STH molecules are essentially confined to the granules but with the immunocytochemical technique before embedding a slightly diffuse reaction appeared in the entire cytoplasm. These results are discussed.This work was supported by a grant from U.E.R. III LilleChercheur I.N.S.E.R.M.     

Cell differentiation of the fetal rat anterior pituitary in vitro

Summary Adenohypophysial primordia of rat embryos at 13 to 15 days gestation were cultured in Parker 199 synthetic medium for 2 to 11 days. At the end of the culture period their fine structure and the presence of immunoreactive trophic hormones using the peroxidase-labeled antibody technique were investigated. The degree of differentiation in the glands depends largely on the age of the embryos furnishing the explants. Cultured pituitaries explanted on the 13th day of gestation contain only ACTH-positive cells and about 15% of the cells are granular. The granules are 50–100 nm in diameter in some cells, while in other cells they range from 50 to 200 nm. In cultivated adenohypophysial primordia of embryos on the 15th day of intrauterine life ACTH, prolactin, LH and TSH cells are evident, but only the same two kinds of granular cells can be observed with the electron microscope. The extent of cytodifferentiation in the glands explanted on the 14th day of gestation is intermediate between the two other groups. The data suggest that the fetal rat pituitary has the capacity of self-differentiation but to a lesser extent than that of the in situ hypophysis.Dedicated to Professor W. Bargmann on the occasion of his 70th birthday     

Immunocytochemical distribution of somatotrophs in porcine anterior pituitary

The objective of this immunohistochemical study was to identify the spatial distribution patterns of growth hormone (GH) secreting cells (somatotrophs) in the newborn and prepubertal porcine pituitary. No differences were observed among the total somatotrophs per unit area across the three ages. There were, however, changes in spatial distribution of somatotrophs in porcine pituitary with developmental age. Distinctive characteristics of the pattern included a high population of somatotrophs (44±1.2; mean ± standard error of the mean per 30,495 m²) in regions 1 and 5 and a low population (22±1.4) in regions 2 and 4 at each level (P<0.05). Somatotrophs increased 55% in region 3 from proximal to distal levels at all ages. With increasing age, however, somatotrophs in region 3 at the proximal level decreased 33%. From these results, we suggest that there may be regional specificity of cellular differentiation and transformation to facilitate GH secretion to meet the need for endocrine regulation as the animal ages.     

Cellular localization of orexins in human anterior pituitary

Orexins A and B are hypothalamic peptides derived from a precursor called prepro-orexin and are associated with the stimulation of food intake and arousal. There is evidence that orexins act on some pituitary functions. Since no studies have been done concerning the presence of orexins in human pituitary, it is unclear whether the local effect of these peptides is due to orexins synthesized in the pituitary or to circulating-derived orexins. To define a possible paracrine regulatory role of orexins on pituitary cell function, we have sought to characterize the expression of orexins in the human adenohypophysis as well as to identify the cell types that express these proteins. In the present study, we used immunohistochemistry and double labeling to detect the presence of orexin A and orexin B in human pituitary. Orexin A was localized in 33% of pituitary cells. With double immunofluorescence techniques we demonstrated that orexin A is present in PRL (82±5.3%), TSH (18±2.3%), GH (10±2.3%), FSH (8±2.6%), and LH (7±3.2%) cells, but not in corticotroph cells. Orexin B was found in virtually all corticotrophs cells of the anterior pituitary. These results demonstrate that lactotroph cells are the main source of orexin A and corticotroph cells of orexin B. In summary the present findings provide the first evidence that orexins A and B are expressed in specific human pituitary cell types. Our data provide the cellular basis for a paracrine role of orexins in human pituitary cell function and further our understanding regarding the mechanisms by which orexins influence neuroendocrine function.