Vascularity in Nontumorous Human Pituitaries and Incidental Microadenomas: A Morphometric Study

Abstract

The aim of the present study was to determine the microvascular angioarchitecture in the lateral and central portions of the anterior lobe as well as of the posterior lobe. The possible association between vascularity and age, sex, and pregnancy was also examined. In addition the vascular density of incidental microadenomas was investigated and compared to that of nontumorous gland. Blood vessels of 120 nontumorous pituitaries and 11 incidental microadenomas obtained at autopsy were examined by immunohistochemistry using the endothelial marker CD 34. Microvascular density (MVD) and microvessel surface density (MSD) were determined by morphometry using an automatic computer image analysis system. MVD and MSD were higher in the anterior than in the posterior lobe. Age, gender, or pregnancy did not affect the angioarchitecture of these sites. No statistical differences in MVD and MSD were observed between central and lateral areas of the anterior lobe, although MVD appeared to be lower in the lateral zones. A marked difference was noted in the vascularity of microadenomas compared to nontumorus tissue; both MVD and MSD were significantly lower in adenomatous tissue. Our studies suggest that the capillary network of the anterior and posterior lobes differ. They also indicate that the microvascular architecture is not significantly affected by age, gender, or pregnancy. Lack of significant angiogenesis in pituitary microadenomas may underlie the low growth rate and infrequency of metastasis of pituitary adenomas.

Endoglin and CD-34 immunoreactivity in the assessment of microvessel density in normal pituitary and adenoma subtypes

“…In previous studies from our group, compared to nontumoral adenohypophyses, decreased microvessel densities were noted in slow-growing pituitary adenoma subtypes [3,4,5,8]. In the present work, this decrease was not apparent on CD-34 preparations, a finding perhaps due to differences in immunostaining method and/or quantitation of staining.…”

“…If blood supply is insufficient, tumors fail to grow, their cells undergoing apoptosis/necrosis. Neoformation of vessels has been the subject of extensive investigation over the past two decades, numerous neoplasms, including pituitary tumors, having been studied [1][2][3][4][5][6][7][8]. Microvessel density can be quantitated in histologic sections immunohistochemically demonstrating various endothelial markers, such as von Willebrand factor, CD-31 and CD-34.…”

Hypoxia Inhibits Expression of Prolactin and Secretion of Cathepsin-D by the GH4C1 Pituitary Adenoma Cell Line

“…Because low concentrations of oxygen have previously been reported to stimulate the expression of angiogenic factors such as vascular endothelial growth factor (VEGF) in tumor cells (Minchenko et al, 1994;Shweiki et al, 1992) and because the GH3 cell line, parental to GH4C1 cells, expresses VEGF (Lohrer et al, 2001;Ochoa et al, 2000;Vidal et al, 2000b), we used RT-PCR to assay transcription of several forms of VEGF in GH4C1 cells in response to hypoxia. Transcription of both the 164 and 120 amino acid variants of VEGF was elevated in GH4C1 cells after hypoxic treatment for 12 hours ( Fig.…”

Cyclooxygenase‐2 expression in human pituitary tumors

“…Details of immunohistochemistry, including the duration of exposure and control procedures for these three stains, as well as the morphometric quantification method have been described in previous publications. 25,26,32,33 Most tumors (n ϭ 119) were fixed in glutaraldehyde, routinely processed, embedded in Epon-Araldite, and studied by transmission electron microscopy.…”