The scanning electron microscope makes it possible to study the horny cells surface, with a very high magnification. In psoriasis, several abnormalities have been previously noticed, among which the presence of microvilli (or granulations) on the horny cells surface. Those microvilli have a diameter of 0.4 millimicr. and are grossly round shaped. On the same cells, or on other ones, holes or pores can be found. Some authors consider these formations as characteristics of psoriasis. According to them, they represent the desmosomes and may be a sign of the immaturity of psoriasic horny cells. In fact, these cells can be found in other diseases of the horny layer, and also on a normal skin. On the contrary, their shape may be more characteristic of the psoriasis. In this disease they seem smaller, more irregular and above all more sparse, and they clearly let appear the cell surface among them.