Serous cutaneous glands in new world hylid frogs: An ultrastructural study on skin poisons confirms phylogenetic relationships between <i>Osteopilus septentrionalis</i> and <i>Phrynohyas venulosa</i>

Delfino, Giovanni; Brizzi, R.; Nosi, Daniele; Terreni, Alessandro

doi:10.1002/jmor.1119

Cited by 18 publications

(11 citation statements)

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“…Comparing experimental findings with patterns observed in the serous glands of control specimens, it appears that secretory discharge from type Ia units occurs as a phasic process whereas type Ib glands apparently display tonic activity of release, slightly influenced by norepinephrine stimulation. Furthermore, patterns detected in type Ia glands after secretory release are consistent with a "bulk discharge mechanism", namely a peculiar holocrine process resulting from intense myoepithelial cell compression, and involving emission of large amounts of secretory product along with portions of cytoplasm (Delfino 1980;Delfino et al 1996Delfino et al , 2001Melis et al 2000). The occurrence of migrating cells in type Ia glands after secretory discharge stresses the degenerative aspects of such a mechanism.…”

Section: Discussionmentioning

confidence: 86%

Serous gland polymorphism in the skin of Phyllomedusa hypochondrialis azurea (Anura, Hylidae): response by different gland types to norepinephrine stimulation

et al. 2002

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Stimulation by norepinephrine in physiological concentration was used on the dorsal skin of the Argentine tree-frog Phyllomedusa hypochondrialis azurea to trigger contraction of myoepithelial cells encircling the serous glands and provoke secretory release. This hylid species possesses two kinds of serous cutaneous glands, producing secretory granules or vesicles (type Ia and Ib serous units, respectively), along with serous-derived glands which synthesise lipids and store them in complex aggregates (type II units). Structural and ultrastructural observations on myoepithelia, secretory units and gland products collected in saline after discharge, revealed consistent but different responses in the three types investigated. Type Ia glands reacted intensely to treatment, with both contractile and secretory responses, type Ib glands were only mildly affected in their myoepithelia and glands of type II were not affected at all. According to data available in the literature, these findings suggest that: (a) the dense (type Ia) granules are expelled as a phasic response through bulk (holocrine) discharge, (b) the secretory (type Ib) vesicles are released as a tonic response through a merocrine mechanism and (c) lipid (type II) aggregates are exuded as a secretory component of a complex behavioural response which tends to reduce transcutaneous water loss. Furthermore, these findings indicate that the use of pharmacological modulation of myoepithelial activity allows selective collection of skin products in species characterised by serous gland polymorphism.

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Section: Discussionmentioning

confidence: 86%

Serous gland polymorphism in the skin of Phyllomedusa hypochondrialis azurea (Anura, Hylidae): response by different gland types to norepinephrine stimulation

et al. 2002

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“…The latter is a common feature in several species of Leptodactylids (Delfino et al, 2001;Alvarez et al, 2005), Hylids (Delfino et al, 2001;Delfino et al, 2002;Terreni et al, 2002), Bufonids (Delfino et al, 1999) and Pseudids (Del- (Delfino, 1976;1979;Delfino et al, 1990;Delfino et al, 2001). Additionally, the larger type II granules of varying densities closely resemble each other in the ancient genera Leiopelma and Bombina (Quagliata et al, 2008).…”

Section: Discussionmentioning

confidence: 89%

“…The secretory content of granular glands can display a wide spectrum of morphological complexity between species, ranging from extremely electron-dense to those showing intricate repeating substructures. The latter is a common feature in several species of Leptodactylids (Delfino et al, 2001;Alvarez et al, 2005), Hylids (Delfino et al, 2001;Delfino et al, 2002;Terreni et al, 2002), Bufonids (Delfino et al, 1999) and Pseudids (Del- Fig. 13.…”

Section: Discussionmentioning

confidence: 99%

“…However, the type II granules in the Leiopelma genus (4 lm) are smaller than those in Bombina (10 lm). It has been shown that the secretory granules of closely related species display comparable or identical morphological traits (e.g., Delfino et al, 2002). Type I and II granules in Leiopelma species exhibit features of perigranular compartmentalisation.…”

Section: Discussionmentioning

confidence: 99%

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Differential polymorphism in cutaneous glands of archaic Leiopelma species

Melzer

Clerens

Bishop

2011

Journal of Morphology

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Endemic New Zealand frogs of the genus Leiopelma are from a basal lineage of extant anurans that release defensive secretions onto their skin when disturbed. Here, we characterize the gross anatomy and microscopic structure of the skin of L. archeyi, L. hochstetteri, and L. pakeka using stereoscopic, light and transmission electron microscopy. The terrestrial L. archeyi and L. pakeka possess dimorphic granular glands, categorized as type I and II, based on their frequency and morphological traits, whereas the semi-aquatic L. hochstetteri lacks type I glands. This is the first report of differential dimorphism in anurans of the same genus. This dimorphism could be interpreted as an adaptation to different physiological or ecological needs of these species. However, species within this ancient genus share similar general gland morphology with other anurans, namely, a secretory unit containing storage granules ensheathed by myoepithelial cells. Type I glands are ellipsoid, large and contain a homogeneous mass of electron-dense granules (1.8 ± 0.08 μm in diameter). Type II glands are round and contain larger heterogeneous granules (4.06 ± 0.16 μm) of varying densities. Exposure to noradrenaline causes the contraction of myoepithelial cells, resulting in bulk discharge of type I glands through the epidermal duct onto the skin surface. Differential release of secretions from dimorphic glands may be indicative of their functional specialisation in antipredatory or regulative roles. Mass spectrometric techniques were used to de novo sequence peptides present in the skin secretions of Leiopelma species. A total of 30 previously undescribed peptides from Leiopelma species were fully or partially sequenced. These peptides exhibited no similarity to any known compounds.

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“…Granular glands, the second type of lissamphibian skin glands are found throughout the skin, but some areas show higher concentrations of enlarged granular gland fields [ 2 , 9 , 11 , 13 , 25 , 31 , 41 , 50 , 51 ]. Although granular glands can differ substantially in form and content amongst lissamphibians, they are generally acinar in nature and are built up by giant cells containing granular material that often fuse into syncytia [ 19 , 23 , 24 , 28 , 29 , 33 , 34 , 52 , 62 , 69 ]. Granular glands are capable of synthesizing and secreting mainly bioactive substances such as amines, peptides, and alkaloids [ 26 ] and are considered the site of skin toxin production and storage (e.g.…”

Section: Introductionmentioning

confidence: 99%

Form and Function of the skin glands in the Himalayan newt Tylototriton verrucosus

2018

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BackgroundAmphibians have evolved a remarkable diversity of defensive mechanisms against predators. One of the most conspicuous components in their defense is related to their ability to produce and store a high variety of bioactive (noxious to poisonous) substances in specialized skin glands. Previous studies have shown that T. verrucosus is poisonous with the potential to truly harm or even kill would-be predators by the effect of its toxic skin secretions. However, little is known on form and function of the skin glands responsible for production and release of these secretions.ResultsBy using light- and scanning electron microscopy along with confocal laser scanning microscopy, we show that T. verrucosus exhibits three different multicellular skin glands: one mucous- and two granular glands. While mucous glands are responsible for the production of the slippery mucus, granular glands are considered the production site of toxins. The first type of granular glands (GG1) is found throughout the skin, though its average size can vary between body regions. The second type of granular glands (GG2) can reach larger dimensions compared with the former type and is restricted to the tail region. Despite their different morphology, all three skin gland types are enwrapped by a distinct myoepithelial sheath that is more prominently developed in the granular (i.e. poison-) glands compared to the mucous glands. The myoepithelial sheath consists of one layer of regularly arranged slender myoepithelial cells that run from the gland pore to the basal gland pole.ConclusionsThis study shows that the skin in the Himalayan newt T. verrucosus displays one mucus- and two poison gland types enwrapped by a myoepithelial sheath. Contraction of the myoepithelium squeezes the glands and glandular content is released upon the skin surface where the secretion can deploy its defensive potential.

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Serous cutaneous glands in new world hylid frogs: An ultrastructural study on skin poisons confirms phylogenetic relationships between Osteopilus septentrionalis and Phrynohyas venulosa

Cited by 18 publications

References 18 publications

Serous gland polymorphism in the skin of Phyllomedusa hypochondrialis azurea (Anura, Hylidae): response by different gland types to norepinephrine stimulation

Serous gland polymorphism in the skin of Phyllomedusa hypochondrialis azurea (Anura, Hylidae): response by different gland types to norepinephrine stimulation

Differential polymorphism in cutaneous glands of archaic Leiopelma species

Form and Function of the skin glands in the Himalayan newt Tylototriton verrucosus

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