Choana

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choana

[′kō·ə·nə]
(anatomy)
A funnel-shaped opening, especially the posterior nares.
(invertebrate zoology)
A protoplasmic collar surrounding the basal ends of the flagella in certain flagellates and in the choanocytes of sponges.

Choana

 

an internal nasal orifice in vertebrates, including man. Choanae evolved after the development of constant or periodic breathing of air. They first arose in crossopterygian and dipnoan fish. In dipnoan embryos, grooves starting from the olfactory sacs change into canals whose internal orifices, or primary choanae, open into the oral cavity. In dipnoan fish, with aquatic respiration, air flows to the lungs through the canals. In terrestrial vertebrates, a naso-oral canal forms during embryonic development and connects with the external nasal orifices, or nostrils, to the oral cavity, where it opens into the primary choanae. In amphibians the choanae remain in this position throughout life. In mammals and in some reptiles and birds the upper part of the oral cavity into which the primary choanae open becomes separated from the lower part because of the development of the secondary hard palate; it forms the nasopharyngeal duct, which opens into the pharyngeal cavity through the secondary choanae. In crocodiles, some birds, and especially mammals the secondary choanae recede farther into the pharynx as the secondary hard palate lengthens. The formation of a nasopharyngeal duct separated from the lower part of the oral cavity and the recession of the choanae close to the larynx enable animals and humans to breathe freely when food is in the oral cavity.

References in periodicals archive ?
Whole genome "jumping libraries" of a prenatal sample identified a translocation breakpoint that disrupted chromodomain helicase DNA binding protein 7 (CHD7), a causal locus in the CHARGE syndrome (coloboma of the eye, heart defects, atresia of the choanae, retardation of growth and/or development, genital and/or urinary abnormalities, and ear abnormalities and deafness), otherwise unidentifiable with current screening technology, the knowledge of which assists with prenatal counseling (68).
These are: C: Coloboma of the eye, central nervous system anomalies; H: Heart defects; A: Atresia of the choanae R: Retardation of growth and/or development G: Genital and/or urinary defects (Hypogonadism) E: Ear anomalies and/or deafness.
Examination of the oral and nasal cavities while the animal was anesthetized revealed mucous entering the oral cavity through the nasal choanae and hyperemic nasal mucosa.
Charge syndrome is a rare autosomal dominant disorder with multiple cardinal features, such as colobomas resulting in visual impairment, heart defects, vestibular malfunction, retarded growth, atresia choanae, and deafness (Pagon, Graham, Zonana, & Young, 1981), affecting approximately 1 in 10,000 babies (Sanlaville & Verloes, 2007).
Choanae rounded, not concealed by palatal shelf of maxillary arch; dentigerous processes of vomers prominent, oblique and moderately separated from each other, median and posterior to choanae, each bearing row of 4-7 teeth; tongue oval, notched posteriorly; 2/3 of its extension adherent to floor of mouth; males with vocal slits and subgular vocal sac; long vocal slits, lateral to tongue.
They are C - Coloboma of the eye, H - Heart defects, A - Atresia of the choanae, R - Retardation of growth, G - Genital and/or urinary defects and E - Ear anomalies.
In the choanae and nasal septae, stellate scars, ulcers, and honeycomb necrotic patches covered with yellow pus (Figure 1, panel B) were seen.
After seeing 13 consultants, at the age of 14 months Jamie was also diagnosed with profound deafness and a severe form of Charge syndrome (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and deafness).
CHARGE syndrome; CHARGE stands for coloboma of the eye, heart defects, atresia of the nasal choanae, retardation of growth and/or development, genital and/or urinary abnormalities, and ear abnormalities and deafness).
The actual length and the ideal length were each measured at the piriform aperture, at the choanae, at half the distance from the tip of the nose to the piriform aperture, and at half the distance from the piriform aperture to the choanae (figure).
29) based on common features of the syndrome: C-- coloboma of the eye (missing part of iris and/or retina); H--heart defects; A--atresia of the choanae (bony or membranous blocking of nasal passage); R--retardation of growth and/or development; G--genitourinary anomalies; E--ear anomalies and/or deafness.
Emily was born with CHARGE (coloboma--a cleft, slit, gap, or fissure of the eye; heart defects; atresia of the choanae [a non-closure of one of the communicating passageways in the upper respiratory system]; retardation of growth and development, and central nervous system abnormalities; genital hypoplasia [small genitalia]; and ear abnormalities which affect several functions of her body).