[Microscopy of the thymus in the perinatal period].

Simple complementary staining technics are useful to reveal some histological particularities which may be underestimated and unsuspected when are used routinal stainings only. Parallel to hematoxylin eosin, it is recommended to investigate the macrophagic cells by their soudanophilic properties on frozen sections, their ceroid like autofluorescent content by PAS and by paraldehyde fuchsin after oxidation. Eosinophils are constant in the thymus during the neonatal period. They result from a local eosinophilopoiesis. They are contrasted by chromotrope 2R or by anilin blue on ultraviolet light. Semi quantitative determination of cellular density and the importance of the macrophagic activity in the cortex are necessary to definite different stages of thymic atrophy. Anatomoclinical correlations demonstrate relations existing between different degrees of thymic atrophy and duration of illness.