The development of mammotroph adenomas in pituitaries of aging female C57BL/6J mice

The development of pituitary adenomas in female C57BL/6J mice was studied over the lifespan. Mammotrophs and somatotrophs, identified by immunocytochemical staining, appeared normal in 3-4 month old animals, with the exception of an occasional hypertrophic mammotroph and, in one gland, a nest of such cells. At 15 months, hypertrophic mammotrophs, somatotrophs and unstained cells occurred singly or in areas of hyperplasia; a mammotrophic adenoma was present in one gland. At 22 months, pituitaries contained mammotroph adenomas or adenomalike mammotroph clusters within hypertrophic, hyperplastic areas as seen in 15 month old glands. Pituitaries from all 28-30 month old mice contained mammotroph adenomas; nests of hypertrophic cells were present in 5 of 8 glands studied. These results suggest that mammotrophic adenomas may arise from hypertrophic mammotrophs, which are often found in nests with other hypertrophic pituitary cell types. However, this study does not exclude the possibility that mammotroph adenomas and hypertrophic mammotrophs occur independently.

Comparison of gonadotroph, thyrotroph and mammotroph development in situ, in transplants and in organ culture

This study was conducted to examine the role of the hypothalamus in development of gonadotrophs, thyrotrophs, and mammotrophs up to the time of birth in the rat. The development of the in situ newborn pituitary (22 days post-coitus; dpc) was compared with the development of 12 and 15 dpc pituitary anlagen grown under the kidney capsule of an adult host or in organ culture for a time period equivalent to 22 days of gestation. Morphological development was evaluated by light microscopic histology and gonadotrophin immunocytochemistry. Functional development was analyzed by radioimmunoassay determination of luteinizing hormone, thyrotrophin, and prolactin content of the in situ, kidney capsule grafted, and organ-cultured pituitary. The results provide evidence that factors, perhaps blood-borne, play a significant role in pituitary development but that direct hypothalamic influences are of minimal importance in the development of gonadotrophs and mammotrophs. The fetal hypothalamus may play a significant role in stimulating high storage levels of thyrotrophin in the prenatal pituitary.

Calcium and the secretory cycle of prolactin cells: a cytochemical and ultrastructural study of dopamine inhibition and monobutyryl cyclic AMP-stimulation of prolactin secretion

To identify intracellular calcium pools that may be involved in the secretory process in prolactin (PRL) cells, hemi pituitaries were incubated in medium containing 10(-6) M dopamine, 5 mM cyclic cAMP (experimentals), or in medium alone (controls) and then processed for electron microscopy using potassium pyroantimonate to localize intracellular calcium. PRL in the medium was measured by radioimmunoassay. The concentration of antimonate associated with mitochondria, Golgi saccules, and secretory granules was estimated. Dopamine inhibition of PRL secretion (> 80% at 1, 2, 3 h) resulted in accumulation of secretory granules in all stages of maturation and dilation of Golgi saccules at 2 and 3 h, accompanied by increased mitochondria antimonate and increased Golgi-associated antimonate. Cyclic AMP stimulation of secretion (635% at 5 min., declining to 34% at 1 h) resulted in marked exocytosis at 5 and 15 min., declining after 30 min. Mitochondrial antimonate decreased after 30 min. Stimulated cells exhibited numerous coated membrane structures at or near exocytotic pits and an amassing of microvesicles at the margin of the Golgi apparatus. Although some secretory granules consistently exhibited reactivity to antimonate (unchanged by inhibition or stimulation), plasma membrane, and granule membrane translocated to the plasma membrane during exocytosis, were not reactive.

Urolithiasis associated with hypercalciuria

Fifty male patients with urolithiasis (UL), associated with idiopathic hypercalciuria (IH), were studied in comparison to a group of 18 male normocalcemic patients with inactive calcium stone disease of unknown etiology. In the group of IH-UL, in addition to hypercaliuria, statistically significant hyperphosphaturia with decreased tubular reabsorption of phosphate and hyperuricemia were observed; there was a tendency to hypophosphatemia although non-significant. In 36% of the IH-UL patients the first episode of renal colic appeared at age 40 to 50. Thirty-eight per cent of the IH-UL patients had recurrent stone formation. Twenty per cent of the IH-UL patients had a family history of urolithiasis. Forty-six per cent of all stones contained oxalate in addition to calcium, and 25% of the stones contained oxalate and phosphate.

Response of tanycytes of rat median eminence to intraventricular administration of colchicine and vinblastine

The effects of colchicine and vinblastine on tanycytes of the rat median eminence have been studied using the electron microscope. Colchicine and vinblastine were administered by intraventricular cannulation into the third ventricle and demonstrated distinct morphological effects on tanycyte microtubules. Highest drug doses administered were 50.0 mug in 5.0 mul of saline initially, followed by an additional 50.0 mug of these agents infused in a volume of 13.0 mul saline over an hour. Colchicine treatment resulted in the formation of large crystalloids within tanycytes, coincident with the disappearance of microtubules, all along the ventricular surface. Nonetheless the tanycytes appeared able to maintain a continuous, tight lining, as in controls, although some crystalloids were observed beneath the ventricular surface, either within tanycyte processes or within neuronal processes. Vinblastine treatment also resulted in the formation of identical crystalloids but at highest doses thoroughly destroyed the tanycyte lining of the median eminence and exposed cellular elements below the surface to the drug. Portal capillaries approaching the ventricular surface were generally free of any signs of drug response to either colchicine or vinblastine.

Ultrastructural changes in the capillary bed of human pituitary tumors

The fine structure of the capillary bed of the anterior pituitary has been studied in 19 cases of pituitary tumor and 1 autopsy specimen. Tumor specimens were less well vascularized than the autopsy specimen. Endothelial cells within tumor specimens were often observed with swollen portions of cytoplasm, or cytoplasmic blebs, projecting into the capillary lumen. Blebbing, in many cases, nearly obstructed the capillary lumen and was most often associated with endothelial cells that had an electron-lucent cytoplasm, in contrast to endothelial cells that had an electron-dense cytoplasm, even within the same capillary profile. Compared with electron-lucent cells, electron-dense cells contained more endothelial filaments. Also observed were capillaries that had apparently broken apart releasing their contents into the pericapillary space and shrunken remnants of capillaries. A number of abnormal features were observed in the pericapillary spaces-ie, disruption of the parenchymal-pericapillary interface, disorganization of basal laminae, increased amounts of plasma proteins and cellular debris within the space and, ultimately, complete loss of the normal limits and characteristics of the space. Similar, though less pronounced, changes were observed in the autopsy specimen. The hypothesis is advanced that changes observed in the capillary bed are, in large part, a result of tumor growth, which increasingly disrupts tissue organization at the parenchymal-pericapillary interface and, because the tumor mass in the sella turcica can only enlarge upwards, compresses the pituitary stalk and portal veins. The result is ischemia and eventual necrosis. The observations are then in good agreement with recent reports on changes in capillary fine structure associated with ischemia.