Das Synatech - Institut für Synergetik und nachhaltige Technologien

Ein Institut der Arnold-Sommerfeld-Gesellschaft e.V. (ASG)
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Ontogenetic Growth of the Membranous Labyrinth

The vestibular labyrinth (Fig. 1) is the non-auditory part of the inner ear that plays the dominant role in the subjective sensation of motion and spatial orientation of the head. The vestibular organ is composed of three semicircular canals and sacculus and utriculus, contains five receptor organs. All five structures contain hair cells and respond to acceleration. The sacculus and utriculus sensing linear motion, the semicircular canals sense angular accelerations and decelerations of the head and enable coordination of posture and body movement, as well as visual stability.

Fig. 1. The left labyrinth of human. The membranous labyrinth were removed manually by means of a scalpel under a dissection microscope and placed in the water bath

The knowledge of the geometry of the vestibular organ during development is important to understand its function. Here we analyzed the shape and size of the membranous labyrinth of vestibular organs in human, rat, rabbit, cat and guinea pig during ontogenetic growth. After manual removal of the membranous labyrinths from the temporal bones (fixed in formalin) they were measured (Fig. 2).

The right  labyrinth of a rat embryo The left labyrinth of a human embryo
Fig. 2. The size and the geometry of the membranous labyrinth

A reliable method of measurement was developed for all three semicircular canals. The analysis revealed that size and shape of the canals changed in correlation to species specific ontogenetic development. Different labyrinth parts showed a different growth pattern, in which individual parts revealed a proportional growth. The shape of the canals underwent a transformation from angular to circular. The spatial orientation of the semicircular canals, utricle and sacculus in all species is stable (Fig. 3).

Fig. 3. The left membranous labyrinths of Wistar rat (2. and 10. postnatal day)

The sizes of all three semicircular canals are increasing during growth. The shape all three semicircular canals changes from irregular angular to oval. The spatial orientation of the semicircular labyrinth is stable during development.

© 2015  Dr. Uwe Renner