Dual nature of mouse periderm structure, function and fate

Area of Science:

• Developmental Biology
• Skin Biology
• Evolutionary Biology

Background:

• The periderm, an embryonic skin layer, is crucial for epidermal development and barrier function.
• Human periderm is a single layer shed prenatally, but its structure and fate in mice are unclear.

Purpose of the Study:

• To investigate the structure and shedding patterns of the mouse embryonic periderm.
• To compare mouse periderm development with that of humans.

Main Methods:

• Electron microscopy was used to examine mouse skin from embryonic day 14.5 to postnatal day 2.
• Periderm structure and desmosome presence were assessed.

Main Results:

• The mouse periderm is bilayered, with a microvilli-covered outer layer and an inner granular layer.
• Desmosomes are scarce between the inner periderm and epidermis, and absent between the two periderm layers.
• The outer periderm sheds in utero (embryonic day 16-18) during barrier acquisition, while the inner periderm is retained postnatally.

Conclusions:

• The bilayered structure and postnatal retention of the mouse inner periderm may be evolutionary adaptations.
• These adaptations could help altricial rodent newborns manage dehydration or facilitate skin bacterial colonization.