Aphthous stomatitis caused by a reduction in numbers of CD4+ T cells may be implicated in RAS-type ulceration in HIV infection. The thickness of the mucosa may be an important factor in aphthous stomatitis. Usually, ulcers form on the thinner, non-keratinizing mucosal surfaces in the mouth. Factors which decrease the thickness of the mucosa increase the frequency of occurrence, and factors which increase the thickness of the mucosa correlate with decreased ulceration. The nutritional deficiencies associated with aphthous stomatitis (Vitamin B12, folate, and iron) can all cause a decrease in the thickness of the oral mucosa (atrophy). Local trauma is also associated
Medieval medicine of Western Europe was one of the "leading Italian universities in teaching medicine, identification and treating of diseases and ailments, specializing in autopsies and workings of the body." The most prestigious and famous part of the university is the oldest surviving anatomical theater, in which students studied anatomy by observing their teachers perform public dissections. Surgery was formally taught in Italy even though it was initially looked down upon as a lower form of medicine. The most important figure of the formal learning of surgery was Guy de Chauliac. He insisted that a proper surgeon should have a specific knowledge of the human