Relationship between Merkel cells and nerve endings during embryogenesis in the mouse epidermis

Area of Science:

• Developmental biology
• Neuroscience
• Dermatology

Background:

• Merkel cells (MC) and nerve endings (NE) exhibit close associations in adult mice.
• The role of MC as potential targets for ingrowing NE during embryogenesis is hypothesized.

Purpose of the Study:

• To investigate the developmental relationship between Merkel cells (MC) and nerve endings (NE) during mouse embryogenesis.
• To quantitatively analyze the formation of MC-NE contacts in the developing epidermis.

Main Methods:

• Double-labeling indirect immunofluorescence (IIF) on frozen whisker pad and back skin from mouse embryos (12-17 days gestational age).
• Utilized cytokeratin antibody for MC detection and neurofilament anti-serum for NE detection.
• Confirmed findings with electron microscopy (EM) observations.

Main Results:

• Merkel cells (MC) were not detected at 12 days gestational age but progressively increased from day 13 to 17.
• MC association with nerve endings (NE) increased significantly, from 57% at day 13 to 95% at day 17 in whisker pads.
• Similar temporal patterns of MC-NE association were observed on the back skin, albeit with a delayed onset.

Conclusions:

• Established the temporal course of MC-NE contact formation during mouse epidermal embryogenesis.
• Demonstrated that MC are present in the epidermis and appendages prior to NE innervation.
• Provided evidence supporting the hypothesis that MC serve as targets for developing nerve endings.