Morphology of the large granular alveoli of the parotoid glands in toad (Bufo ictericus) before and after compression

Toledo, R.C; Jared, Carlos; Brunner, A

doi:10.1016/0041-0101(92)90008-s

Cited by 40 publications

(41 citation statements)

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“…Toads in particular have highly toxic venom that is produced by well-developed postorbital parotid glands [2]. The cardiovascular effects of toad venom on vertebrates are well known and have been extensively investigated, particularly in the genus Rhinella [3,4].…”

Section: Introductionmentioning

confidence: 99%

Presynaptic neuromuscular action of a methanolic extract from the venom of Rhinella schneideri toad

Rostelato‐Ferreira

Belo

Leite

et al. 2014

J Venom Anim Toxins incl Trop Dis

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BackgroundRhinella schneideri, previously known as Bufo paracnemis, is a common toad in many regions of Brazil. Its venom exerts important cardiovascular effects on humans and other animals. Although this toad venom has been the subject of intense investigations, little is known about its neuromuscular activity.MethodsThe neurotoxicity of a methanolic extract of R. schneideri venom was tested on mouse phrenic nerve-diaphragm (PND) preparations mounted for conventional twitch tension recording – in response to indirect stimulation – and for electrophysiological measurements.ResultsVenom extract (50 μg/mL) increased the muscle twitch tension in PND preparations but did not significantly alter the resting membrane potential values. Electrophysiological evaluations showed that the extract (50 μg/mL) significantly augmented the frequency of miniature end-plate potential (from 38 ± 3.5 to 88 ± 15 after 60 minutes; n = 5; p < 0.05) and quantal content (from 128 ± 13 to 272 ± 34 after five minutes; n = 5; p < 0.05). Pretreatment with ouabain (1 μg/mL) for five minutes prevented the increase in quantal content (117 ± 18 and 154 ± 33 after five and 60 minutes, respectively).ConclusionThese results indicate that the methanolic extract of R. schneideri venom acts primarily presynaptically to enhance neurotransmitter release in mouse phrenic-diaphragm preparations.

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Section: Introductionmentioning

confidence: 99%

Presynaptic neuromuscular action of a methanolic extract from the venom of Rhinella schneideri toad

Rostelato‐Ferreira

Belo

Leite

et al. 2014

J Venom Anim Toxins incl Trop Dis

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“…Although the subepidermal capillary network does not play a major role in respiration among toads (Czopek, 1965;Machin, 1969), it is very important in the hydric balance of these terrestrial animals (Czopek, 1965;Schmid, 1965;McClanahan, 1967;Bentley, 1969;McClanahan and Baldwin, 1969;Roth, 1973). The subcutaneous capillaries are associated with the parotoid glands, which contain bufogenins, biogenic amines, and glycosaminoglycans, all of which are suspected to be involved in either osmotic balance, hydric balance, or both (Elkan, 1968;Vialli et al, 1969;Dapson, 1970;Lillywhite, 1971;Le Quang Trong, 1975a,b;Matoltsy and Bereiter-Hahn, 1986;Lichtstein et al, 1992;Toledo et al, 1992;Toledo and Jared, 1993). This suggests that the parotoid glands and their vasculature may serve additional functions beyond that of defense.…”

Section: Discussionmentioning

confidence: 96%

“…The myoepithelium of the parotoid glands is involved in active transport and discharge of the secretion, whereas the secretory syncytium is involved in toxin synthesis (Hostetler and Cannon, 1974;Cannon and Hostetler, 1976;Erspamer, 1994). The synthesized toxins are stored in the syncytia of the secretory units, and the parotoid gland reportedly exhibits discharge processes that involve loss of cytoplasm when the animal is agitated or when the glands are manually compressed (Hostetler and Cannon, 1974;Cannon and Hostetler, 1976;Toledo et al, 1992).Anurans are capable of synthesizing more types of biogenic amines, peptides, and steroids than any other vertebrate (Barthalmus, 1994). The secretion of the parotoid glands contains biogenic amines and noncardiotonic and cardiotonic steroids (Siperstein et al, 1957;Zelnik et al, 1964;Chen and Kovarikova, 1967).…”

mentioning

confidence: 99%

“…These cutaneous glands consist of a duct, an intercalated tract, and a secretory unit (Delfino, 1976). The secretory unit of a granular gland is embedded in the stratum spongiosum and consists of a secretory syncytium (Toledo et al, 1992;Toledo and Jared, 1995) lined by a contractile sheath (myoepithelium). That syncytium synthesizes toxins, which are stored in the granules of the gland (Erspamer, 1994).…”

mentioning

confidence: 99%

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Vasculature of the parotoid glands of four species of toads (bufonidae: bufo)

Hutchinson

Savitzky

2004

Journal of Morphology

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The parotoid glands of toads (Bufonidae) consist of large aggregations of granular glands located between the otic region of the skull and the scapular region. To determine the circulatory pattern of these glands, we perfused the vascular systems of Bufo alvarius, B. marinus, B. terrestris, and B. valliceps with either India ink or Microfil, a fine latex. The perfused glands were studied by gross dissection, microscopic examination, and histology. The vascular patterns of the parotoid glands were compared to the arrangement of vessels in the dorsal skin of Rana sphenocephala (Ranidae), a frog that lacks parotoid glands. The parotoid glands of the four species of toads are supplied with blood by the lateral and dorsal cutaneous arteries and are drained by one or more branches of the internal jugular vein. The dorsal cutaneous artery supplies most of the blood to the parotoid glands in B. terrestris and B. valliceps. In B. alvarius and B. marinus, both the lateral and dorsal cutaneous arteries serve major roles in the blood supply of the glands. These patterns of blood flow have not been described previously for parotoid glands and conflict with earlier accounts for B. alvarius and B. marinus. The arteries and veins associated with the parotoid glands of toads are present in R. sphenocephala, but are arranged differently. In R. sphenocephala, the lateral cutaneous artery supplies the dorsal and lateral skin posterior to the shoulder region, whereas the dorsal cutaneous artery supplies the skin of the shoulder region. In toads, both the lateral and dorsal cutaneous arteries supply the skin of the shoulder region and ramify into subcutaneous capillaries that surround the secretory units of the parotoid glands. Extensive vasculature presumably is important for delivering cholesterol and other precursor molecules to the parotoid glands, where those compounds are converted into toxins.

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“…The mucus produced in mucous glands is homogenous and slimy, and it is composed principally of mucopolysaccharides, which maintain skin moisture and provide skin protection from damage through prolonged contact with water, and also reduce water loss through evaporation (Li et al 2006). Granular glands synthesize considerable amounts of bioactive peptides and aromatic biogenic amines (Nakajima 1981;Roseghini et al 1989) that help protect the organism from the enemies (Toledo et al 1992) and regulate the water balance of the skin (Delfino et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Localization of prolactin receptor in the dorsal and ventral skin of the frog (Rana ridibunda)

et al. 2010

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Abstract:The dorsal and ventral skin in amphibians plays an important role in osmoregulation. Prolactin hormone is involved in regulation of amphibian skin functions, such as water and electrolyte balance. Therefore, amphibians may be useful as a model for determining the sites of the prolactin receptor. In this study, prolactin receptor was detected in frog dorsal and ventral skin using immunohistochemical staining method. Prolactin receptor immunoreactivity was localized in all epidermal layers except stratum corneum of dorsal skin epidermis, stratum germinativum layer of ventral skin epidermis, myoepithelial cells, secretory epithelium and secretory channel cells of granular glands in both skin regions. The mucous glands and secretory granules of granular glands did not show immunoreactivity for the prolactin receptor. According to our immunohistochemical results, the more widespread detection of prolactin receptor in dorsal skin epidermis indicates that prolactin is more effective in dorsal skin. Presence of prolactin receptors in epidermis points out its possible osmoregulatory effect. Moreover, detection of receptor immunoreactivity in various elements of poison glands in the dermis of both dorsal and ventral skin regions suggests that prolactin has a regulatory effect in gland functions.

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Morphology of the large granular alveoli of the parotoid glands in toad (Bufo ictericus) before and after compression

Cited by 40 publications

References 15 publications

Presynaptic neuromuscular action of a methanolic extract from the venom of Rhinella schneideri toad

Presynaptic neuromuscular action of a methanolic extract from the venom of Rhinella schneideri toad

Vasculature of the parotoid glands of four species of toads (bufonidae: bufo)

Localization of prolactin receptor in the dorsal and ventral skin of the frog (Rana ridibunda)

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