Histological development and integration of the Zebrafish Weberian apparatus

• Published in: Developmental dynamics Vol. 249; no. 8; pp. 998 - 1017
• Main Authors: Bird, Nathan C., Richardson, Selena S., Abels, Jeremy R.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.08.2020; Wiley Subscription Services, Inc
• Subjects: Bladder; Danio rerio; Developmental stages; Functional integration; Genetic analysis; Hearing; inner ear; Integration; Maturation; Morphogenesis; Morphology; Notochord; ontogeny; Ossification; soft tissue; Soft tissues; Swim bladder; Weberian ossicles; Zebrafish; soft tissue; swim bladder; Danio rerio; ossification; inner ear; ontogeny; Weberian ossicles
• ISSN: 1058-8388; 1097-0177
• DOI: 10.1002/dvdy.172

Background The Weberian apparatus enhances hearing in otophysan fishes, including Zebrafish (Danio rerio). Several studies have examined aspects of morphological development of the Weberian apparatus and hearing ability in Zebrafish. A comprehensive developmental description including both hard and soft tissues is lacking. This information is critical for both interpretation of genetic developmental analyses and to better understand the role of morphogenesis and integration on changes in hearing ability. Results Histological development of hard and soft tissues of the Weberian apparatus, including ossicles, ear, swim bladder, and ligaments are described from early larval stages (3.8 mm notochord length) through adult. Results show a strong relationship in developmental timing and maturation across all regions. All required auditory elements are present and morphologically integrated early, by 6.5 mm SL. Dynamic ossification patterns and changes in shape continue throughout the examined developmental period. Conclusions This study provides the first comprehensive histological description of Weberian apparatus development in Zebrafish. Morphological integration was found early, before increases in hearing ability were detected in functional studies (>10 mm total length), suggesting morphological integration precedes functional integration. Further research is needed to examine the nature of the functional delay, and how maturation of the Weberian apparatus influences functionality. Key Findings First full ontogenetic description of soft and hard tissue development in the zebrafish Weberian apparatus across all regions (ear, vertebrae, swim bladder). All elements of the Weberian apparatus are present and integrated early in development (6.5 mm SL). System integration is present before functional advantage was detected in previous studies.