A scanning and transmission electron microscopic study of the lung of a caecilian Boulengerula taitanus

Abstract

The lung of an apodan amphibian Bouiengerula taitanus has been investigated by scanning and transmission electron microscopy. This caecilian has only a single, long tubular lung that tapers towards the caudal end of the body. The lung has a central air duct which radially opens into a single stratum of alveoli lined by well developed septa that attach to two diametrically opposite trabeculae. The trabeculae carry the pulmonary artery and vein. The septa have blood capillaries on both surfaces and supportive and contractile elements like collagen, smooth muscle, elastic tissue and fibrocytes. The alveolar surface has only a single population of pneumocytes that combine the morphological features of the mammalian type 1 and 2 cells, i.e. they contain the osmiophilic, lamellated bodies and are squamous in form. Through subepithelial cytoplasmic invaginations, the pneumocytes, together with their basement lamina, were observed to be firmly attached to the septa1 tissue elements, presumably to avoid mechanical detachment during the rapid respiratory movements. The compartmentation of the whole lung in this species is viewed as a means of increasing the surface area available for gas exchange which, coupled with other already established cardiovascular adaptations in this species, may be of significance in its fossorial mode of life, an environment that is usually hypoxic and hypercarbic.

Histology of the trachea and lung of Siphonops annulatus (Amphibia, Gymnophiona)

“…They were also found in Gymnophiona by Welsch (1981), Patle et al (1977) and Maina & Maloly (1988) and in our material in the non respiratory cubic epithelium present, covering the surface of some septa.…”

“…Contrary to the description of Marcus (1937) that ciliated cells do not occur in the lungs of Gymnophiona and are scarce in Afrocaecilia (Maina & Maloly, 1988), our material shows that this type of epithelium occurs in quantity in the surface of the Lungenbronchus, a situation present in other Amphibia (Goniakowska-Witalinska, 1995).…”

Termitivore or detritivore? A quantitative investigation into the diet of the East African caecilian Boulengerula taitanus (Amphibia: Gymnophiona: Caeciliidae)

“…Boulengerula taitanus Loveridge is a dedicated subterranean burrower and Taita Hills endemic (Nussbaum and Hinkel, 1994). Although presumably native to naturally occurring forest, B. taitanus is now widespread in agricultural areas, and its ease of capture has resulted in several studies which include physiology (Wood et al, 1974), morphology (Maina and Maloiy, 1988) and diet (Hebrard et al, 1992). Hebrard et al (1992: 513) stated that "the most frequent countable items in the guts were the head capsules of extremely small termites".…”

Study of the spatial organization of the gas exchange components of a snake lung – the sandboa Eryx colubrinus (Reptilia: Ophidia: Colubridae) – by latex casting

“…Stinner, 1982). Butler, 1895;Maina & Maloiy, 1988) and the largely legless burrowing squamates, the amphisbaenians (Butler, 1895). Scanning electron microscopic studies on cast and uncast preparations have been pro®tably carried out in studies of mammalian (e.g.…”