Morphological and morphometric study on human Scarpa ganglion development

Abstract

Conclusion: In Scarpa neurons the cell and nuclear area increases and nuclear/cytoplasm ratio decreases with fetal age (p < 0.0001). There are statistically significant differences in cell area between all fetal groups, except for the interval 45–74 mm crown-rump-length (CRL). Displacement of a neuron within the internal auditory meatus (IAM) occurs from 9 weeks in the fetus until the neonate. Methods: A light microscopic histomorphometric study of the Scarpa ganglion in human fetuses from spontaneous abortions measuring 45, 74, 90, 134, 145 and 270 mm CRL and a from a 1-day-old neonate (360 mm) was carried out. Cell and nuclear area, ganglion area and distances from the Scarpa ganglion neurons to the endocranial porus of the IAM were measured. Results: In the 45, 74, 90 and 134 mm CRL human fetuses the cartilaginous labyrinthine capsule appears divided by the facial nerve and the Scarpa ganglion into two compartments: rostral and dorsal. Ovoidal Scarpa ganglion in the 45 mm CRL lies within the IAM near its endocranial porus (15 µm). In the otic capsule of the 145 mm CRL fetus an endochondral ossification appears in the IAM base, where Scarpa ganglion neurons are displayed in two groups: superior and inferior divided by a vascular-connective septum. This anatomy remains from this specimen until the neonate specimen.

Keywords::

• Cranial base ossification
• myelinization
• neuronal migration
• apoptosis

Acknowledgements

With pleasure we express our gratitude to Prof. J. Bilbao, Statistic Professor of the School of Medicine Basque Country University and to U. Agirre Larrakoetxea PhD from the Research Department of Galdacano Hospital (Vizcaya, Spain), for their professional advice and supervision in the statistical elaboration of our morphologic findings.

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