Person:
Rodríguez Vázquez, José Francisco

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First Name
José Francisco
Last Name
Rodríguez Vázquez
URI
https://hdl.handle.net/20.500.14352/79600
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Medicina
Department
Anatomía y Embriología
Area
Anatomía y Embriología Humana
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Author: Abe, Sin Ichi ×

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    Closure of the middle ear with special reference to the development of the tegmen tympani of the temporal bone
    (Journal of Anatomy, 2011) Rodríguez Vázquez, José Francisco; Murakami, Gen; Verdugo López, Samuel; Abe, Sin Ichi; Fujimiya, Mineko
    Closure of the middle ear is believed to be closely related to the evolutionary development of the mammalian jaw. However, few comprehensive descriptions are available on fetal development. We examined paraffin-embedded specimens of 20 mid-term human fetuses at 8-25 weeks of ovulation age (crown-rump length or CRL, 38-220 mm). After 9 weeks, the tympanic bone and the squamous part of the temporal bone, each of which was cranial or caudal to Meckel's cartilage, grew to close the lateral part of the tympanosquamosal fissure. At the same time, the cartilaginous tegmen tympani appeared independently of the petrous part of the temporal bone and resulted in the petrosquamosal fissure. Subsequently, the medial part of the tympanosquamosal fissure was closed by the descent of a cartilaginous inferior process of the tegmen tympani. When Meckel's cartilage changed into the sphenomandibular ligament and the anterior ligament of the malleus, the inferior process of the tegmen tympani interposed between the tympanic bone and the squamous part of the temporal bone, forming the petrotympanic fissure for the chorda tympani nerve and the discomalleolar ligament. Therefore, we hypothesize that, in accordance with the regression of Meckel's cartilage, the rapidly growing temporomandibular joint provided mechanical stress that accelerated the growth and descent of the inferior process of the tegmen tympani via the discomalleolar ligament. The usual diagram showing bony fissures around the tegmen tympani may overestimate the role of the tympanic bone in the fetal middle-ear closure.
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    Human fetal hyoid body origin revisited
    (Journal of Anatomy, 2011) Rodríguez Vázquez, José Francisco; Kim, Ji Hyun; Verdugo López, Samuel; Murakami, Gen; Cho, Kwang Ho; Asakawa, S; Abe, Sin Ichi
    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.