title: Human fetal hyoid body origin revisited.
abstract: The hyoid body is traditionally believed to have a dual origin from second and third arch mesenchyme, but this theory remains controversial. We examined paraffin-embedded sections from the hyoid region of 12 embryos and fetuses at 5-7 weeks of gestation (11-22 mm cranio-rump length). We found that the second (Reichert's cartilage) and third arch mesenchymal condensations did not reach the median area at the base of the tongue. Rather, a midline mesenchymal condensation was seen, and it separated from these arches at an early stage. This condensation was triangular and plate-like, and the cranial part was narrow between the bilateral Reichert's cartilages, while the caudal part was wide along the mediolateral axis between the bilateral primitive greater horns. We considered the midline mesenchymal condensation as the hyoid body anlage. At 7 weeks, a cartilaginous mass appeared in the midline condensation. The hypoglossal nerve changed its direction at the superolateral ends of the midline condensation. We propose that: (i) the hyoid body originates from the hypobranchial eminence via the midline condensation; (ii) the lesser horn originates from the caudal end of Reichert's cartilage; and (iii) the greater horn of the hyoid and the superior cornu of the thyroid cartilage originate from the third arch cartilage. The second and third arches may not regulate early hyoid body morphology.
authors: Department of Human Anatomy and Embryology II, Faculty of Medicine, Complutense University, Madrid, Spain.
authors: Jose Francisco
authors: JF
authors: Rodríguez-Vázquez
authors: Ji Hyun
authors: JH
authors: Kim
authors: Samuel
authors: S
authors: Verdugo-López
authors: Gen
authors: G
authors: Murakami
authors: Kwang Ho
authors: KH
authors: Cho
authors: Sachiko
authors: S
authors: Asakawa
authors: Shin-Ichi
authors: S
authors: Abe
references: J Anat. 2005 Nov;207(5):501-61
references: 16313391
references: Development. 1998 Sep;125(17):3445-59
references: 9693148
references: Dev Dyn. 2003 Oct;228(2):239-46
references: 14517995
references: Anat Embryol (Berl). 1978 Jun 12;153(3):279-86
references: 677475
references: Development. 2000 Sep;127(17):3815-28
references: 10934026
references: Acta Anat (Basel). 1985;122(3):163-84
references: 4013651
references: Development. 2009 Feb;136(4):637-45
references: 19168678
references: Acta Otolaryngol. 1981 May-Jun;91(5-6):323-36
references: 7270109
references: Mech Dev. 2004 Apr;121(4):387-95
references: 15110048
references: Development. 2005 Nov;132(22):4927-36
references: 16221728
references: Ann Otol Rhinol Laryngol. 1975 Jan-Feb;84(1 Pt 1):49-55
references: 1111434
references: J Anat. 2006 Feb;208(2):179-89
references: 16441562