A comparative morphologic and morphometric study about geniculate ganglion development in man and in rat

Abstract

Conclusions: Human–rat geniculate ganglion (GG) have multiple origins: (1) An initial proximity (20 μm) to the endocranial foramen of the IAM, suggests neural crest induction; and (2) The influence of epibranchial placodes: the tensor tympani muscle (TTM) and the otic apical coil.

Objectives: This study was undertaken to determine the comparative development of human–rat GG.

Materials and methods: A light microscopic study of the GG in human material obtained from spontaneous abortions at 9, 13, 14, 17, 18, and 30 weeks, and one neonate was done. This study examined Webster rat embryos and a post-natal series. Specimens were fixed in Bouin fluid, embedded in paraffin, cut, and stained with H&E. The histomorphometric data were obtained with image analysis software.

Results: The human fetus of 9 weeks presents two neuronal groups in the VII nerve: one near (20 μm) the IAM endocranial foramen, foraminal, and the other, tympanic. Neonate GG is located between the TTM and the cochlear apex (inwards). In the 16 day old rat embryo GG is placed within a canal containing the stapedial artery. In the adult rat the GG and the stapedial artery are placed within the IAM.

Keywords:

• Neural crest induction
• cranial base ossification
• apoptosis
• neuronal migration
• geniculate ganglion development

Acknowledgments

With gratitude we recognize J. Bilbao, Statistic Professor of the School of Medicine, Basque Country University, Spain, his professional and excellent advice in the management and interpretation of the statistical data of this research. This research study is in Honor to Professor Michel Portmann, Honorary President of 2016 Annual Corlas Meeting, for his Academic career dedicated to the study and teaching of ENT diseases.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.