Postnatal remodeling of the laryngeal airway removes body size dependency of spectral features for ultrasonic whistling in laboratory mice

Abstract

In many mammals, spectral properties of acoustic signals scale with body size within and among species. In rodents, however, despite drastic changes in body size, fundamental frequency (F0) range of ultrasonic whistles produced for social communication remain relatively uniform from birth to adulthood. Such divergent patterns may be due to a novel sound production mechanism unique to rodents involving an intralaryngeal midline pocket termed the ventral pouch. In this study, we analyzed the postnatal shape and size of the laryngeal airway in CD1 mice over ontogeny to better understand the association between ventral pouch geometry and F0 of ultrasonic whistles. Ventral pouch volume (0.06 ± 0.01 mm3) did not differ between pups and 1‐year‐old adults despite extensive shape‐inducing remodeling of the intralaryngeal musculature and connective tissue. In contrast, ventral pouch volume was 50% less in 2‐year‐old compared to 1‐year‐old mice. Thus, allometry of the laryngeal airway appears to explain spectral overlap between ultrasonic whistles of young, small mice and older, larger mice. The causal association between the reduction in vocal behavior and a seemingly shrinking ventral pouch in geriatric mice remains unclear. Together, these data inform our understanding of the postnatal development and remodeling of the intralaryngeal airway in Mus musculus.

Postnatal changes in thyroid cartilage shape and cartilage matrix composition are not synchronized in Mus musculus

“…The mouse larynx appears to be a malleable organ. Vocal fold morphology (Kolachala et al, 2010;Lungova & Thibeault, 2020), intralaryngeal lumen (Darwaiz et al, 2022), size and shape of the cartilaginous framework (Abdelkafy et al, 2007;Riede et al, 2020), and cartilage radio density (this study) show all characteristic postnatal changes throughout the entire life of a laboratory mouse. Contrastenhanced micro-CT provides a promising tool to investigate the very small and complex mouse larynx identifying species differences (Borgard et al, 2020) and genetic birth defects (Bottasso-Arias et al, 2023).…”

“…The mouse larynx consists of a cartilaginous framework, musculature, connective tissue, and epithelium (Lungova et al., 2018; Mok et al., 2020; Riede et al., 2020; Roberts, 1975; Tabler et al., 2017). The shape of the mouse larynx cartilages and the intralaryngeal airway change postnatally until at least 1 year of age (Darwaiz et al., 2022; Riede et al., 2020). To advance our understanding of the remodeling process of the mouse larynx, we tested whether age‐related shape changes in the thyroid cartilage are associated with characteristic changes in overall radio density and whether radio density is associated with muscle or ligament attachments.…”