![Marsh frog (Pelophylax ridibundus) in a pond with inflated vocal sacs on either side of its head used to amplify its sound to attract mates Stock Photo - Alamy Marsh frog (Pelophylax ridibundus) in a pond with inflated vocal sacs on either side of its head used to amplify its sound to attract mates Stock Photo - Alamy](https://c8.alamy.com/comp/2BHETCY/marsh-frog-pelophylax-ridibundus-in-a-pond-with-inflated-vocal-sacs-on-either-side-of-its-head-used-to-amplify-its-sound-to-attract-mates-2BHETCY.jpg)
Marsh frog (Pelophylax ridibundus) in a pond with inflated vocal sacs on either side of its head used to amplify its sound to attract mates Stock Photo - Alamy
![Animal biology. Biology; Zoology; Physiology. THE MULTICELLULAR ANIMAL 63 branes. Specialization for secretion and excretion leads to gland formation. Glands may be unicellular and scattered here and there in the surface Animal biology. Biology; Zoology; Physiology. THE MULTICELLULAR ANIMAL 63 branes. Specialization for secretion and excretion leads to gland formation. Glands may be unicellular and scattered here and there in the surface](https://c8.alamy.com/comp/RN5N7G/animal-biology-biology-zoology-physiology-the-multicellular-animal-63-branes-specialization-for-secretion-and-excretion-leads-to-gland-formation-glands-may-be-unicellular-and-scattered-here-and-there-in-the-surface-of-the-cellular-membrane-or-they-may-be-grouped-at-certain-points-of-vantage-just-as-often-however-many-cells-combine-to-form-multicellular-glands-which-sink-as-it-were-below-the-surface-as-simple-or-complex-tubes-or-sacs-of-secreting-cells-and-thus-amplify-many-fold-the-effective-surface-within-a-given-space-and-finally-specialized-epithelial-cells-form-important-RN5N7G.jpg)
Animal biology. Biology; Zoology; Physiology. THE MULTICELLULAR ANIMAL 63 branes. Specialization for secretion and excretion leads to gland formation. Glands may be unicellular and scattered here and there in the surface
![The active site of SacHÀNADPHÀSAC-A and enzymatic mechanism. (A) The... | Download Scientific Diagram The active site of SacHÀNADPHÀSAC-A and enzymatic mechanism. (A) The... | Download Scientific Diagram](https://www.researchgate.net/publication/364238680/figure/fig5/AS:11431281130793991@1679933442006/The-active-site-of-SacHANADPHASAC-A-and-enzymatic-mechanism-A-The-binding-of-SAC-A.png)
The active site of SacHÀNADPHÀSAC-A and enzymatic mechanism. (A) The... | Download Scientific Diagram
![He inflates his vocal sacs on his throat, providing an effective chamber to amplify the sound of air rushing across his vocal chords. Each species has its own specific call -- it's He inflates his vocal sacs on his throat, providing an effective chamber to amplify the sound of air rushing across his vocal chords. Each species has its own specific call -- it's](https://preview.redd.it/bm0tpuygfax51.jpg?auto=webp&s=52c02e49559ee3dbb69c94544e74165545dbd509)