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- Volume 13 (1994)
- Number 1 - Proceedings of the sixth European congr...
- Morphometry of the pituitary gland of growth hormone-transgenic mice
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Morphometry of the pituitary gland of growth hormone-transgenic mice
Abstract
The pituitary glands of 30 transgenic mice (TM) expressing the bovine growth hormone (bGH) gene under the transcriptional control of the rat phosphoenol-pyruvate-carboxy-kinase promoter (PEPCK) as well as of 30 controls were investigated with stereological methods. The volume of the total pituitary, the adenohypophysis, and the neurohypophysis were estimated in paraffin sections using Cavalieri’s principle. The numerical density of the growth hormone- (GH), prolactin- (PRL) and somatomammotropic (SOMA) cells as well as the size of the GH-cells were investigated on immunohistochemically stained sections. The volume fraction of all cell types was estimated using the point counting method. Mean volume, numerical density, and total number of the immunostained cells were measured by model-based stereological techniques following the method of Weibel and Gomez (1962). In comparing TM with age- and sex-matched controls, significant changes were detected: Both the weight and the volume of the pituitary glands were increased in female TM, whereas they were decreased in male TM. No differences were noted in the volume of the intermediate lobe or of the neurohypophysis. The volume fraction of GH- and SOMA-cells was reduced, both in male and in female TM, whereas the volume fraction of the PRL-cells was reduced in male TM and increased in female TM. The decrease of GH-immunopositive cells in TM was due both to a reduction in the number and in the size of somatotropic cells in GH-TM. These morphological data support the negative feedback mechanism caused by the protracted oversecretion of GH in various organs.