Contributions to Zoology, 76 (4) – 2007

Kugelzellen in larval anuran epidermis: an ultrastructural study on tadpoles of Pelobates cultripes (Pelobatidae) and Phyllobates bicolor (Dendrobatidae)

Giovanni Delfino1, Sara Quagliata1, Filippo Giachi1, Cecilia Malentacchi2

1.  Dipartimento di Biologia Animale e Genetica dell’Università di Firenze, via Romana 17, 50125 Firenze, Italy,

2.  Dipartimento di Fisiopatologia clinica dell’Università di Firenze, viale Pieraccini 6, 50139 Firenze, Italy

Keywords: anuran larvae.

We analysed limbless tadpoles in the ontogenetic range 23-27, marked by development of operculum and labial teeth (Gosner, 1960). Epidermis maintains a stable structure in these stages, until cutaneous glands develop during toe morphogenesis (Delfino et al., 1991). Tadpoles of Pelobates cultripes - six specimens - and Phyllobates bicolor - eight specimens - were collected near Ciudad Real (Spain) and Medelin (Colombia), respectively, and sacrificed with 0.1% chlorobutanol. Skin strips, 9 mm2, were fixed in the Karnovsky (1965) solution, postfixed in 1% OsO4 (both in cacodylate buffer) and embedded in Epon 812. Semi-thin sections of 1.5 µm thickness (for the LM) were stained with buffered (1%, borax) toluidine blue, ultrathin sections with a hydroalcoholic saturated solution (25 mg/ml) of uranyl acetate followed by alkaline lead citrate (2 mg/ml). Ultrathin sections were observed (80 KV) with a Siemens 101 TEM.

Fig. 1. Epidermis structure in limbless tadpoles of Phyllobates bicolor (a-b, LM micrographs) and Pelobates cultripes (c, LM micrograph; d, TEM micrograph). A. KZn and pavement cells varying in cytoplasm density. B. Mitotic pattern (encircled) in KZ and mucous granules (mg) in pavement cell. C. KZn with different cytoplasm densities and melanin granules (p). D. KZn vary considerably in both cytoplasm density and filament content. (*)(*)(*) ◊ (*) = decreasing cytoplasm density, small arrows in a and b point to microridges, arrowheads in a-d to basal tonofilament patches, large arrow in d to peripheral cytoskeleton.