Prenatal growth and development of the modern human labyrinth

The modern human bony labyrinth is morphologically distinct from that of all other primates, showing derived features linked with vestibular function and the overall shape of the cranial base. However, little is known of how this unique morphology emerges prenatally. This study examines in detail th...

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Bibliographic Details
Published in:Journal of anatomy 2004-02, Vol.204 (2), p.71-92
Main Authors: Jeffery, Nathan, Spoor, Fred
Format: Article
Language:English
Subjects:
basicranium
cochlea
Cochlea - embryology
Ear, Inner - embryology
Embryonic and Fetal Development - physiology
Female
Humans
Magnetic Resonance Imaging
ontogeny
Original
Petrous Bone - embryology
phylogeny
Pregnancy
Pregnancy Trimester, First
Pregnancy Trimester, Second
semicircular canals
Semicircular Canals - embryology
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Summary:The modern human bony labyrinth is morphologically distinct from that of all other primates, showing derived features linked with vestibular function and the overall shape of the cranial base. However, little is known of how this unique morphology emerges prenatally. This study examines in detail the developing fetal human labyrinth, both to document this basic aspect of cranial biology, and more specifically, to gain insight into the ontogenetic basis of its phylogenetically derived morphology. Forty‐one post‐mortem human fetuses, ranging from 9 to 29 weeks gestation, were investigated with high‐resolution magnetic resonance imaging. Quantitative analyses of the labyrinthine morphology revealed a number of interesting age‐related trends. In addition, our findings show that: (1) the prenatal labyrinth attains an adult equivalent size between 17 and 19 weeks gestation; (2) within the period investigated, shape changes to all or most of the labyrinth cease after the 17–19‐week size maturation point or after the otic capsule ossifies; (3) fetal cochlea development correlates with the surrounding petrosal morphology, but not with the midline basicranium; (4) gestational age‐related rotations of the ampullae and cochlea relative to the lateral canal, and posterior canal torsion are similar to documented phylogenetic trends whereas other trends remain distinct. Findings are discussed in terms of the ontogenetic processes and mechanisms that most likely led, in part, to the emergence of the phylogenetically derived adult modern human labyrinth.
ISSN:0021-8782
1469-7580
DOI:10.1111/j.1469-7580.2004.00250.x