Histologische Untersuchungen an der bindegewebigen Wurzelscheide des Sinushaarfollikels bei der Katze: das Sinuskissen ; Histological study on the inner layer of the dermal root sheath of the cat’s sinus hair follicle – The “sinuskissen”

In the sinus hair follicle of the cat, there is a prominent local modification of the inner layer of the dermal root sheath which protrudes like a bulge into the anular sinus. This “sinuskissen” (“ringwulst” in the papers published in English) is the subject of this study in which attention is directed on two major aspects: (1) the cytological and histological features of the “sinuskissen” as well as (2) its three-dimensional extension. Light microscopical methods (e.g. PAS stain, Alcian blue stain [pH 2,5], and Resorcinfuchsin stain for elastic fibres), electron microscopy and three-dimensional modelling yielded results as follows: (1) The “sinuskissen” consists of a connective tissue with relatively few cells and a high amount of ground substance. Fibrocytes with their long interdigitating processes are distributed in a loose network of collagen fibres. The amorphous ground substance has a relatively low content of glycoproteins and proteoglycanes, as it is characteristic for a loose connective tissue. As such conditions make the “sinuskissen” susceptible to changes of aqueous flow, related functional consequences are discussed in details. (2) The “sinuskissen” has an asymmetrical shape in the sinus hair follicle of the cat. The heterogeneity in terms of size and shape is highlighted by the reconstructions from serial sections. The three-dimensional models demonstrate that the “sinuskissen” has either the shape of a completely closed ring, or it is an incomplete ring (with variations between three quarters or half of the circumference). Special attention is paid to the fact that the closed ring is not placed horizontally, but in an oblique plane that is between the horizontal and vertical plane. The incomplete ring, too, can have an oblique position, appearing as a spiral structure. ; Im Sinushaarfollikel der Katze ragt das Sinuskissen - als lokale Modifikation der inneren bindegewebigen Wurzelscheide - in den Sinus anularis vor. Mit Blick auf die im Schrifttum teilweise widersprüchlichen Beschreibungen galt ...