DEVELOPMENTAL BIOLOGY OF TONGUE OF ROUSETTUS LESCHENAULTI

Abstract

There are 4,800 species of mammals currently living on Earth. These mammals are divided into three subclasses i.e. Prototheria, Metatheria and Eutheria. These three subclasses are further divided into 26 or more orders. These are all species of mammals that exhibit tremendous morphological, physiological and developmental diversity. Yet embryonic development has been studied in only a few mammalian species. Among mammals, bats are second only to rodents with regards to species number and habitat range and are the most abundant mammals in undisturbed tropical regions. Bats, the second largest order of mammals and characterized as the only mammals to have evolved true flight are divided into two suborders, the Megachiroptera and Microchiroptera. In mammals the tongue can be classified as intra-oral; Marsupialia (Dasyurus, Sarcophilus, Trichosurus): Rodentia (Rattus): Carnivora (Felis canis): Artiodactyla (Camelus, Bovis, Ovis): Perissodanivora (Equus): Primates (Homocallicebus) and extraoral : Monotremata (Tachyglossus): Marsupialia (Tarsiper): and Pholidota (manis). The intra-oral tongue are mainly spatulate-shaped and oval in cross section provided with bilateral lingual arteries, veins and nerves, while the extra-oral tongue are fusiform in shape and either triangular or circular in cross section with single lingual artery veins and nerves. In the present study, it is examined the staged development of tongue of Rousettus leschenaultia at the early limb bud stage, late limb bud stage, paddle stage, phalange stage, late prenatal stage, postnatal stage and adult. The tongue of embryo of R.L. shows well developed tongue, dorsal surface covered with lingual papillae; below the epithelium a well - developed network of lingual muscles and blood vessels. Mucous and salivary glands were well developed and embedded in the connective tissue at the posterior region. At fetal stage, the epithelium layer of tongue appeared to be periderm. Fungiform papillae were developed earlier than filiform papillae. Just after the birth, the periderm disappeared and few filiform papillae were developed.