Vocal Sac of Rana ridibunda: A Morphological and Immunohistochemical Study

The goal of this study is to investigate the structure of the vocal sac in males of Rana ridibunda and to detect the presence of prolactin receptor immunohistochemically under light microscopy in its components The vocal sac of Rona ridibunda were bilaterally localized on each side of the mouth and contained two different layers, namely an internal and an external sheath. External and internal sheaths were formed with multilayered squamous keratinized epithelium and single layered columnar epithelium with rarely ciliated cells, respectively. The connective tissue under the epithelium in the internal sheath possessed predominantly skeletal muscle fibers. Furthermore, the prolactin receptor immunoreactivity was observed in the uppermost cell layer of the epidermis in the external sheath. This paper is one of the first studies for the purpose of displaying the morphological aspects of the bilaterally located vocal sac and its hormonal interaction. In our opinion, this study also contributes to the field of amphibian reproductive biology.