Table 2:

Summary of qualitative description of laryngeal defects in three cartilages and the trachea. A total of 4 control (Bmp4 ^f/f ) (+/+), 4 heterozygote Foxg1Cre;Bmp4 ^f/wt (+/−) and 5 mutants Foxg1Cre;Bmp4 ^f/f(−/−) embryos were investigated. No defect was found in four control fetuses. One of the four heterozygous mutants showed a laryngeal malformation and all 5 homozygous mutants showed different laryngeal malformations. Findings for heterozygotes and mutants are explained. Numbers in parenthesis indicate the number of specimens in which the respective defect was observed. The defects are also illustrated in figure 2. As comparison for a normal shape, we used descriptions by Riede et al. (2020) for reference. CTJ: crico-Thyroid joint, CAJ: crico-arytenoid joint

Heterozygotes

Mutants

Thyroid cartilage: cartilage was fragile and asymmetric (n=1). Cricoid cartilage incomplete and asymmetric (n=1).

Thyroid cartilage: caudal horns are asymmetric in length and angulation toward the thyro-cricoid joint (n=2). Cricoid cartilage: Parts or complete cartilage is absent (n=3). There is a hole or gap/cleft in the dorsal cricoid lamina (n=4). Lateral horns which participate in CTJ are reduced and asymmetric; and the CTJ is malformed (n=2). Reduced facet which participates in CTJ (n=2). Arytenoid cartilage: Muscular process underdeveloped or absent (n=2). Cartilage is fused with cricoid cartilage in CAJ (n=2). Trachea: Only the cranial five tracheal rings are developed. Airway is collapsed caudal from the fifth tracheal ring (n=5).