Chorda tympani innervation of anterior mandibular taste buds in the chicken (Gallus gallus domesticus)

Abstract

While the mammalian chorda tympani innervates taste buds on the anterior two-thirds of the tongue, the chorda tympani of chickens does not enter the tongue, but rather is reported to supply the oral epithelium of the lower beak subjacent to the tongue. This study in the chicken investigated whether the integrity of taste buds in the lower beak is normally dependent upon innervation by the chorda tympani. Following unilateral ligation and removal of a large section of the chorda tympani, animals were sacrificed at 11, 14, and 21 days postoperatively. Oral tissue between the lingual frenulum and beak tip was serially examined, and the presence of each bud was recorded, noting the point at which the bud opened into the oral cavity. No buds were observed on the operated side in any of the cases, while the average bud count on the unoperated side was 33 +/- 10 (SD). On the unoperated side, taste buds were generally associated with anterior mandibular salivary gland ducts that reached surface epithelium and opened into the oral cavity. On the operated side, the cellular organization adjacent to gland ducts and in duct-free epithelium appeared as in control (i.e., bud-free) epithelium. The number of salivary gland duct openings into the oral cavity was equivalent on the operated and control sides. It is concluded that the chorda tympani of chickens innervates taste buds in the anterior lower beak epithelium and that it functions to maintain the structural integrity of these buds.

Lingual BDNF and NT-3 mRNA expression patterns and their relation to innervation in the human tongue: Similarities and differences compared with rodents

“…In chickens, there is little perigemmal innervation (outside the taste bud proper), and taste buds receive innervation from both chorda tympani and trigeminal nerves (Ganchrow et al, 1986(Ganchrow et al, , 1998.…”

Evolution of the Avian Brain and Senses

“…Taste receptors mostly occur within the mandible and upper jaw, and the tongue (Berkhoudt, 1985) and send sensory information to the brain by way of the facial nerve (CN VII) and the lingual branch of the glossopharyngeal nerve (CN IX) (Berkhoudt, 1985;Ganchrow et al, 1986). Although birds generally have fewer taste receptors than most mammals and reptiles, their number among species is variable.…”

Role of neurotrophin in the taste system following gustatory nerve injury

“…Remaining, uninnervated taste buds are smaller than normal and lack taste pore (Oakley et al 1993), and therefore they are named as taste bud remnants. The number of taste buds lost and the remnants remaining following gustatory nerve section differs across animal species, which include rat, hamster, mouse, dog, cat, chicken and fish (Guagliardo and Hill 2007;Ji et al 2014b, c;Oakley et al 1993;Segerstad et al 1989), but also include dog, cats, chickens and fish (Ganchrow et al 1986;Ji et al 2014a;Olmsted 1922;Torrey 1936). For our purposes the most important species is the mouse.…”