Three types of cutaneous glands in the skin of the salamandrid Pleurodeles waltl. A histological and ultrastructural study

Abstract

Histological and ultrastructural investigations revealed three different multicellular skin gland types in the salamandrid Pleurodeles waltl. The mucous glands are small, with one layer of secretory cells surrounding a central lumen; they produce the viscous and slippery mucus film that has various functions in amphibians. The serous glands can be divided based on their histological and ultrastructural characters into the granular gland Type I (GGI) and the granular gland Type II (GGII). The first type (GGI) is moderately sized and distributed throughout the body surface, with higher concentrations in the parotoid and back regions. In contrast, the second type (GGII) is very large (for Pleurodeles) and was found only in the tail, with highest concentration in the tail dorsum. Both granular gland types contain mainly proteinaceous materials but differ in their morphological features including size, shape, cellular organization and vesicle distribution, vesicle size and vesicle shape. Both GGI and GGII are especially concentrated in body parts that are presented to an attacking predator and are hypothesized to produce repellent to poisonous substances to thwart potential aggressors.

Morphological characterization of the glandular system in the salamander Plethodon shermani (Caudata, Plethodontidae)

“…Ensatina eschscholtzii oregonensis) (Kuchta et al, 2008) and with non-glue producing Plethodontidae (e.g. Plethodon cinereus, Eurycea bislineata) (Nowak and Brodie, 1978;Heiss et al, 2009;Sever and Siegel, 2015) and Salamandridae (e.g. Pleurodeles waltl) (Brodie and Gibson, 1969;Sever, 1989;Hecker et al, 2003;Largen and Woodley, 2008;Heiss et al, 2009) indicates similarities in the overall gland morphology and chemistry.…”

“…Plethodon cinereus, Eurycea bislineata) (Nowak and Brodie, 1978;Heiss et al, 2009;Sever and Siegel, 2015) and Salamandridae (e.g. Pleurodeles waltl) (Brodie and Gibson, 1969;Sever, 1989;Hecker et al, 2003;Largen and Woodley, 2008;Heiss et al, 2009) indicates similarities in the overall gland morphology and chemistry. In all five species the granular gland reacts positively for basic glycoprotein components (with a weak to strong PAS and Biebrich Scarlet/Bromphenol Blue/Naphthol Yellow S reaction) (Sever and Siegel, 2015;present study).…”

“…for defense) and the smaller mucous glands synthesize acidic glycoproteins forming the viscous mucus (Brodie and Gibson, 1969;Sever, 1989;Fontana et al, 2006;Largen and Woodley, 2008). However, the anatomical organization of the cutaneous glands and the nature of the chemical substances vary across salamander species and appear to be related to different functions (Hecker et al, 2003;Fontana et al, 2006;Heiss et al, 2009). It has been suggested that in Plethodon shermani the dorsal granular glands secrete the sticky secretions, while the ventral granular glands discharge during scent marking (Largen and Woodley, 2008).…”

Hurt yourself to hurt your enemy: new insights on the function of the bizarre antipredator mechanism in the salamandridPleurodeles waltl

“…The skin secretion of P. waltl also contains some poisonous components (Nowak & Brodie Jr, 1978;Heiss et al, 2009) that passively may seep into the body through the self-induced wounds, and yet we observed no selfintoxication by the newts. We therefore assume that P. waltl is immune against its own toxins.…”

“…Being numerous, small to moderate in size and having soft skin, some of them are common prey for a huge variety of predators from all classes of vertebrates, as well as for certain arthropods (Duellman & Trueb, 1994). Amphibians have therefore evolved various morphological, physiological and behavioural features, which, alone or in combination, provide varying degrees of protection from potential predators (Duellman & Trueb, 1994;Heiss et al, 2009).…”