Talk:Gastrointestinal Tract - Mouth Development

2011

Early fetal development of the intermediate tendon of the human digastricus and omohyoideus muscles: a critical difference in histogenesis

Clin Anat. 2011 Oct;24(7):843-52. doi: 10.1002/ca.21182. Epub 2011 Apr 27.

Katori Y1, Hyun Kim J, Rodríguez-Vázquez JF, Kawase T, Murakami G, Hwan Cho B.

Abstract The digastricus and omohyoideus muscles are known to carry two muscle bellies connected by an intermediate tendon. However, according to our histological observations of 22 fetuses (7-20 weeks of gestation), the mode of formation of the intermediate tendon was critically different between these two muscles. At 7-9 weeks, the posterior belly of the digastricus carried a definite intramuscular tendon continuous with a long descending tendon. The stylohyoideus, external carotid artery and hypoglossal nerve appeared to impede attachment of the tendon to the Reichert or hyoid cartilage. The digastricus anterior belly did not contain any intramuscular tendon, but desmin-positive muscle fibers consistently surrounded a bulb-like mesenchymal condensation at the caudal free end of the digastricus posterior tendon. Thus, most parts of the digastricus tendon were apparently derived from the posterior belly. In contrast, the omohyoideus always possessed a single long muscle belly until 15 weeks. The intermediate tendon first appeared at 15 weeks as a short plate-like connective structure along the medial margin of the muscle. Vimentin immunoreactivity suggested the presence of mechanical stress along the plate-like tissue, possibly due to bending of the long muscle. Muscle fibers were replaced by collagen fibers to form an intermediate tendon by 20 weeks. Copyright © 2011 Wiley-Liss, Inc. PMID 21538565

2001

Prenatal development of the muscles in the floor of the mouth in human embryos and fetuses from 6.9 to 76 mm CRL

Ann Anat. 2001 Nov;183(6):511-8.

Radlanski RJ1, Renz H, Tabatabai A.

Abstract

The development of the muscles in the floor of the mouth is described in 10 human embryos and fetuses ranging from 6.9 to 76 mm CRL by means of computer-aided graphical 3D-reconstructions. All primordia of the muscles in the floor of the mouth could be identified from the 15.6 mm CRL stage on. The proportions and insertion lines of the early muscles were found to be different from adult anatomy. Each muscle first inserted in the medial surface of Meckels cartilage, but during the developmental period between 19 and 68 mm CRL the insertion lines were gradually transposed to the bony ridges of the mandible which progrediently embraced Meckels cartilage. The fibers of the mylohyoid muscles left the anterior region near the symphysis mentalis free during all stages of this study. The digastric muscle revealed only one belly with a constriction of its continuous fibers where it passed the hyoid bone primordium. There was no attachment of digastric muscle fibers to the hyoid; only geniohyoid and mylohyoid fibers. Geniohyoid and genioglossus muscles basically correspond to their definite arrangement, but they underwent proportional changes. Individual specimens embodied irregularities such as accessory geniohyoid and hyoid portions and muscle fibers separate from the mylohyoide muscle.

PMID 11766522

1996

Development of the submandibular gland and its closer neighboring structures in human embryos and fetuses of 19-67 mm CRL

Ann Anat. 1996 Dec;178(6):509-14.

Guizetti B1, Radlanski RJ.

Abstract The fetal development and arrangement of the human submandibular gland was studied by means of serial sections of human embryos and fetuses ranging from 19 mm to 67 mm CRL. Computer assisted 3-dimensional reconstruction leads to the following observations: 1. The orifice of the submandibular duct is located in the medial paralingual sulcus. 2. There is evidence that the extension and location of WHARTON's duct is influenced by the surrounding structures. 3. The surface of the submandibular gland primordium shows impressions of the neighboring structures. 4. The glandular tissue is encapsulated in condensed mesenchyme. PMID 9010566

Ann Anat. 1996 Dec;178(6):503-8.

Development of the parotid gland and its closer neighboring structures in human embryos and fetuses of 19-67 mm CRL

Guizetti B1, Radlanski RJ.

Abstract

The fetal development of the human parotid gland was studied by means of serial sections of human embryos and fetuses ranging from 19 mm to 67 mm CRL. Analysis of computer assisted 3-dimensional reconstructions and anatomical drawings leads to the following observations: 1. The parotid gland anlage is found at the most lateral and cranial point of the sulcus buccalis. 2. The location of the orifice of the parotid duct is dependent upon the developmental processes of the fetal skeleton. 3. The anlagen of anatomical structures dominating the parotid bed in the adult are found prior to the enlargement of the parotid gland. 4. The surface of the parotid gland shows impressions of the surrounding structures. 5. There is no evidence that the parotid gland is subdivided into two lobes by the facial nerve. PMID 9010565