Expression of gap junction protein cx43 in developing mice epidermis

الملخص EN

Gap junctions are intercellular channels responsible for the exchange of ions, second messengers and small metabolites between adjacent cells, and formed of connexin protein subunits.

Although connexin 43 (Cx43) is commonly described to be expressed by keratinocytes, there is scanty studies that immuohistochemically followed the changes in the expression of Cx43 associated with skin development.

The aim of the current study was to investigate the pattern of the expression of Cx43 in keratinocytes during different stages of skin development.

Mouse embryos (12, 14, 16, 18 and 20 days of gestation) were fixed in Bouin's or in 2.5 % glutaraldehyde, and processed for paraffin or resin embedding.

Skin was studied by the light and electron microscope to follow the morphological changes of the differentiated keratinocytes.

Immunohistochemistry was performed on paraffin sections from skin of each embryonic age to explore the progress in the expression of Cx43 during different developmental times.

Epidermis from 12 day-embryos was formed of 2 layers of undifferentiated epithelium, basal layer and periderm, with thickness about 10 μm.

At 14 days of gestation, an intermediate layer appeared between the basal layer and periderm.

The intermediate layer differentiated into stratum spinosum and stratum granulosum, and the periderm disappeared by day 16 of gestation.

Stratification gradually increased with advanced ages and the skin layers were more prominent by 20 days of gestation, where the epidermal thickness reached about 50 μm.

At 12 days of gestation, Cx43 expressed could not be detected, while by 14 days, it was seen in the intermediate and periderm layers, but the reaction was completely absent in the basal cell layer.

The Cx43 expression intensity increased with skin development and by 20 days of gestation, the expression of Cx43 was restricted mostly into stratum spinosum and to less extend into stratum granulosum, but was completely absent from stratum basal and stratum corneum.

The different pattern of Cx43 expression during skin development suggests that Cx43-mediated gap junction may play an important role in skin development