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Updated: Jun 23, 2026
05:19
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Parotoid macroglands in toad (Rhinella jimi): their structure and functioning in passive defence
Carlos Jared1, Marta M Antoniazzi, Amarildo E C Jordão
1Laboratório de Biologia Celular, Instituto Butantan, 05503-900 São Paulo, Brazil. carlosjared@butantan.gov.br
Summary
Toads defend themselves by expelling venom from parotoid glands when threatened. Mechanical pressure, like a predator
Area of Science:
- Zoology
- Toxicology
- Comparative Anatomy
Background:
- Toads (Rhinella) possess parotoid macroglands for defense.
- Venom discharge requires mechanical pressure on these glands.
- Previous descriptions of Rhinella jimi parotoid structure exist.
Purpose of the Study:
- To describe the structure of Rhinella jimi parotoids.
- To investigate the mechanism of venom discharge.
- To understand the defensive role of parotoid glands.
Main Methods:
- Structural analysis of Rhinella jimi parotoids.
- Manual compression mimicking predator attack.
- Observation of venom discharge post-compression.
Main Results:
- Parotoids feature honeycomb-like collagenous alveoli.
- Alveoli contain syncytial glands with myoepithelium and ducts.
- Ducts have thick epithelium, forming a narrow central slit; compression empties glands via a thin jet.
Conclusions:
- Mechanical pressure likely expels venom through narrow ductal slits.
- This mechanism may be common across bufonids.
- Parotoids are specialized cutaneous organs for passive defense.
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