Histomorphometry of mast cells in the convexity of human intracranial dura mater.

Mast cells, known as pro-inflammatory effector cells, are immunocytes present in the meninges and may be involved in the pathophysiology of migraine. This study aims to evaluate the histomorphometric parameters of mast cells located in the convexity of the human intracranial dura mater. For this, samples of intracranial dura mater from eight human fresh cadavers were collected between 8- and 24-h post-mortem. The whole samples were fixed and, subsequently, two fragments of 1.5 cm² each were cut from four different areas of the dura mater convexity, containing a segment of the middle meningeal artery, totaling 64 fragments. After histological processing, the fragments were submitted to microtomy (5 and 10 µm), stained with toluidine blue (0.1%), or immunohistochemically labeled for tryptase, and analyzed using optical microscopy. The following histomorphometric parameters were evaluated: distance from mast cells to vessels, the density of mast cells, and percentage of mast cells with degranulation. Histomorphometric analyzes showed a higher density of mast cells in the vicinity of blood vessels (arterial and venous), with distances around 0-150 µm. A greater number of mast cells was detected near venous vessels in the periosteal layer (17.0 ± 10.1 cells/mm²) than in the meningeal layer (14.1 ± 7.0 cells/mm²) (p < 0.05). Mast cells from the region close to the superior sagittal sinus were found in greater quantity close to the venous vessels (16.7 ± 10.1 cells/mm²) than to the arterial vessels (11.2 ± 7.5 cells/mm²) (p < 0.05). In short, in the convexity of the human intracranial dura mater, mast cells are located close to blood vessels, with a greater number of cells next to the venous vessels of the periosteal layer and in the proximal region of the superior sagittal sinus.