The identification and distribution of the mucous secreting cells in the integument of the Schaap’s dragonet, Callionymus schaapii , Bleeker, 1852

The microanatomical structure of mucous secreting cells (Ms) in fish has been widely found; however, there is a lack of research on the Schaap’s dragonet, Callionymus schaapii , which is regarded as an important benthic fish. The identification and distribution of Ms in different areas along the integumentary system of Callionymus schaapii were therefore demon strated and compared using histochemical techniques. The integument system of this fish consists of two layers: an outer epidermis and an underlying dermis. In particular, the Ms can be classified because they were positively stained with periodic acid-schiff and alcian blue methods. As a result, the distribution of Ms could be observed in all areas (lateral head, pectoral – pelvic, middle trunk and caudal areas) and along with the integumentary system, respectively. The observation confirmed that the highest number of Ms was found in the pectoral-pelvic area. The caudal area had the lowest number of this cell. The localization and abundance of Ms in the integument may support the behavior and enhance swimming to the area under the estuarine conditions.