Ultimobranchial body (post-bronchial or telobranchial body)
Ultimobranchial Body Introduction: It is the last structure derived from the pharyngeal pouches. Hence, it is called ultimobranchial body.
Table of Contents
1. Ultimobranchial Body Origin: There are different views
- They arise purely from pharyngeal endoderm.
- Recent data suggests that neural cells migrate into post-branchial bodies and ultimately becomes secretory component of these structures.
Read And Learn More: Face Anatomy Notes And Important Questions
2. Ultimobranchial Body Comparative anatomy
- This is a constant feature in all vertebrates.
- In sub-mammalian vertebrates, they remain as discrete bodies in the neck or mediastinum throughout adult life.
3. Ultimobranchial Body Fate: It fuses with the thyroid gland and its cells disseminate within it, giving rise to parafollicular cells of the thyroid gland. They are also called C cells to indicate that they produce calcitonin, a hormone that is involved in the regulation of the normal calcium level in the body fluid.
4. Ultimobranchial Body Applied anatomy: C cell hyprplasia is associated with medullary carcinoma and has been reported within the neck. These are presumed to be remnants of ultimobranchial body.
Question 1: What are the various developmental anomalies of face?
Answer: 1. Anomalies: Most of the anomalies of the face are due to failure of union of different processes, which form face.
2. Facial cleft or nasolabial furrow: It is due to failure of fusion between lateral nasal process and the maxillary process.
It may be unilateral or bilateral.
Nasolacrimal duct is absent in this anomaly.
3. Harelip (usually upper harelip): It may be median or lateral. Lateral harelip may be unilateral or bilateral.
- Median harelip is due to failure of fusion of right and left median nasal processes of front nasal process.
- Lateral harelip: It is very common and due to failure of fusion of median nasal process and maxillary process.
- Very rarely there may be failure of fusion of mandibular arches and results into split lower lip.
4. Macrostomia or wide opening of the mouth: It is due to failure or lesser degree of fusion between mandibular and maxillary processes.
5. Microstomia (small oral fissure): It occurs due to excessive fusion of maxillary and mandibular processes.
6. Another rare anomalies area of nose may be absent.
- Proboscis: A cylindrical projection of nose below the forehead.
- Cyclops: Fusion of two eyeballs.
Development of face
1. Chronological age: 5th month of intrauterine life.
2. Germ layer
- Upper lip: Ectoderm and mesoderm.
- Lower lip: Ectoderm and mesoderm.
- Cheek and vestibule of mouth: Ectoderm
3. Sources: It develops from 5 processes
- Unpaired frontonasal process which divides into medial and lateral nasal processes.
- Paired maxillary processes.
- Paired mandibular processes.
4. Upper lip: Frontonasal prominence appears cranial to stomodeum.
Local thickenings of nasal placode appear on either side of frontonasal process.
Nasal placodes dip to form nasal pit.
Lateral to the nasal pit is lateral nasal prominence and medial to it is medial nasal prominence.
Maxillary prominence moves medially and meets the medial nasal prominence, thus forming the upper lip.
It is formed by
- Left and right medial nasal prominences
- Left and right maxillary prominences.
- Nasolacrimal groove: It is junction of lateral nasal process and maxillary process.
Solid cords of ectodermal cells grow from the floor of the groove and get buried. - Nasolacrimal duct: The nasolacrimal groove gets canalized and forms the nasolacrimal duct.
- Nasolacrimal sac: Upper part of nasolacrimal duct forms the nasolacrimal sac while the lower part forms the nasolacrimal duct.
5. Lower lip is formed by fusion of right and left mandibular processes.
6. Anomalies: Most of the anomalies of the face are due to failure of union of different processes, which form face.
1. Facial cleft or nasolabial furrow: It is due to failure of fusion between lateral nasal process and the maxillary process. It may be unilateral or bilateral.
Nasolacrimal duct is absent in this anomaly.
2. Harelip (usually upper harelip): It may be median or lateral. Lateral harelip may be unilateral or bilateral.
- Median harelip is due to failure of fusion of right and left median nasal processes of front nasal process.
- Lateral harelip: It is very common and due to failure of fusion of median nasal process and maxillary process.
- Very rarely there may be failure of fusion of mandibular arches and results into split lower lip.
3. Macrostomia or wide opening of the mouth: It is due to failure or lesser degree of fusion between mandibular and maxillary process.
4. Microstomia (small oral fissure): It occurs due to excessive fusion of maxillary and mandibular processes.
5. Another rare anomalies area of nose may be absent.
- Proboscis: A cylindrical projection of nose below the forehead.
- Cyclops: Fusion of two eyeballs.
Frontonasal process of embryo
1. Chronological age: Fifth week of intrauterine life.
2. Genn layer: Core of mesoderm and is covered by ectoderm.
3. Site: Around stomodeum.
4. Process: The ectoderm which covers the caudal surface of the forebrain vesicle proliferates and together with the overlying surface ectoderm form the frontonasal process.
1. It is divided into a
1. Median nasal process. It extends more caudally and forms bilateral elevations known as the globular processes.
It gives rise to the
- Nasal septum,
- Philtrum of the upper lip, and
- Primitive palate
2. Two lateral nasal processes form the alae of the nose.
5. Anomalies
- Central harelip: It is produced by the failure of the fusion of the right and left globular swellings with each other.
- Lateral harelip: It is caused by failure of fusion between the maxillary process and globular swelling.
- Facial cleft: It is produced by failure of fusion of lateral nasal process with the maxillary process.
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