Morphology and ultrastructure of the gills in two Urodela species:Salamandrina terdigitataandTriturus carnifex

Abstract

Gill morphology and ultrastructure are described for Triturus carnifex and Salamandrina terdigitata with emphasis on differences occurring between two species that inhabit different aquatic biotopes. The morphology and ultrastructure have been studied using light microscopy and both scanning and transmission electron microscopy. The general organization of the gills is similar in the two species and shows the characteristics of Urodela larvae in which the gills consist of three tufts of filaments supported by gill arches III, IV and V. However, some differences are noticeable in the length of the main filament and in the number of secondary lamellae: in T. carnifex, a pond-dwelling salamander, the main filaments are long and rich in secondary lamellae; in the stream-type larva of S. terdigitata, the main filaments are shorter and show a lower number of secondary lamellae, located in its proximal portion. The cellular composition of the gill filament and of respiratory lamellae is different in S. terdigitata: in the gill filament basal cells, pavement cells, ciliated cells, club-shaped cells, mitochondria rich cells (MRCs) and Leydig cells have been recognized, while in the secondary lamellae the last cellular type does not appear. On the contrary, in T. carnifex we observe the same cellular composition in both filament and secondary lamellae.

Morphological Alterations in the External Gills of Some Tadpoles in Response to pH

“…36 The importance of the gill apparatus in terms of respiration has been discussed by some scholars. 37 However, there are a few studies on the external gills of tadpoles with regard to the effects of low pH. 24,38 In fact, no recent reports are available in the existing literature on the effects of low and high pH on the external gills of anuran tadpoles, except our recent findings.…”

“…32 The latest finding suggested that amphibian gills play a crucial role in oxygen uptake and osmoregulation. 37 However, it has been suggested that gill damage in amphibian larvae may not be the sole cause of death among the larvae, as oxygen uptake is not merely restricted to the gills; it is also absorbed through the skin. 49 It should be noted that the comparative morphology of the external gills of some species of anurans has received less attention possibly due to the fact that they do not last long.…”

Morphological And Molecular Analyses of an Anatomical Novelty: The Pelvic Fin Filaments of the South American Lungfish

“…A and B). This general epithelial organization is typical of anuran external gills (Brunelli et al., ) and the gill filaments of teleost fish (Laurent and Dunel, ’80), and facilitates gas exchange from the environment to the blood. Likewise, the external gills of juvenile African lungfish Protopterus dolloi also show blood vessels separated from the external environment by only one or two cell layers (Fig.…”

“…The epithelial surface of anuran external gills when visualized with scanning electron microscopy (SEM) is characterized by the presence of three cellular types: polyhedric pavimentous cells equipped with microridges, cells rich in microvilli, and ciliated cells (Brunelli et al., ). Here, we have imaged the epithelium of PFFs from specimens collected in the dry and rainy seasons.…”

“…Cutaneous air breathing may also occur and the extent of gas exchange is dependent on the density and the diffusion distance (total distance gases must diffuse across an epithelium) (Graham, ). In organs specialized in gas exchange such as external gills, the diffusion distance is reduced, as capillaries are separated from the outside environment by only one or two cell layers (Laurent and Dunel, ; Brunelli et al., ). While the external morphology of PFFs resembles external gills, direct histological comparisons between external gills and PFFs have not been reported.…”