Ultrastructure of Kolmer's crystalloid in the pinealocytes of the common spiny mouse (Acomys cahirinus dimidiatus).

Light- and electron-microscopical observations revealed a rod-like inclusion body in the pinealocytes of the common spiny mouse (Acomys cahirinus dimidiatus). Ultrastructurally, the body is composed of a varying number of tubes whose wall consists of thin filaments aligned in helical arrangement. The inner and outer surface of the wall is covered with ribosome-like granules. Based on a morphological analysis it is concluded that the body described in the present investigation is identical with Kolmer's crystalloid of horizontal cells in the human and primate retina.