Document Type : Original Article
Authors
1
Department of Anatomy and Histology, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt
2
Department of Histology, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt
3
Department of Urology and Pediatric Urology, University of Giessen, Giessen, Germany
Abstract
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.
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