Fetal development of external nose cartilages

Area of Science:

• Developmental biology
• Human anatomy
• Cartilage development

Background:

• The precise timing and mechanism of nasal capsule cartilage division into lateral nasal cartilage (LNC) and greater alar cartilage (GAC) remain unclear.
• The developmental sequence of the medial crus of the GAC is also poorly understood.

Purpose of the Study:

• To investigate the timing and process of nasal capsule cartilage development, specifically the separation of LNC and GAC.
• To determine the developmental timeline and origin of the medial crus of the GAC.

Main Methods:

• Histological examination of 22 human fetal nasal capsules.
• Crown-rump length measurements ranged from 45-350 mm, corresponding to approximately 9-40 weeks of gestational age.

Main Results:

• The LNC and GAC separated from the nasal capsule cartilage between 10-12 weeks.
• The medial crus of the GAC appeared after 27 weeks, seemingly developing independently from the septal cartilage.
• At birth, LNC and GAC remained separate from the septal cartilage, with connections likely forming postnatally.

Conclusions:

• This study elucidates the developmental stages of key nasal cartilages, including LNC, GAC, and its medial crus.
• The findings suggest that postnatal development plays a crucial role in establishing the connections between these cartilages and the septal cartilage.