சைட்டாலஜி & ஹிஸ்டாலஜி ஜர்னல்

Characteristics of the Skin of the Female Albino Rats in Different Ages:Histological, Morphometric and Electron Microscopic Study

Abstract

Sherif Mohamed Zaki

Introduction: Ageing leads to alterations and progressive changes in the skin structures. The data regarding many structural skin changes with ageing are conflicting in both humans and rats. The most recent correlative method between ages of rat with that of the human is using the developmental phase of rat�?¢�?�?��?�??life. Aim: The aim of the present work was to study the characteristics of the skin structures of the female albino rats at different ages based on the different phases of the rat life. This was done through histological, morphometric and electron microscopy study.
Material and methods: Forty eight female rats were used. They were divided into six groups. The studied groups were early weaning, late weaning, pre-pubertal, adolescent, adulthood and aged-phase groups. The histological sections were stained with Haematoxylin and Eosin, Orcein and Gomori’s trichrome stains. The morphometric measurements included: epidermal thickness (μm), dermal thickness (μm), number of hair follicles, number of sebaceous glands, elastic fibre optic density and average area of collagen fibres. Electron microscopy study was also done.
Results: The epidermal thickness increased in the adolescent group, but decreased in the pre-pubertal and adolescent groups. It became thinner and flattened in the adulthood and aged-phase groups. The epidermal cells, stratum basale, stratum spinosum and stratum granulosum were not affected by the ageing process. A relatively flattening of the dermal-epidermal junction was observed in the adulthood and aged-phase groups. The dermal thickness decreased in the adulthood and aged-phase groups. The hair follicles reached their maturation since the early weaning period. They were deeper in their position in the weaning, pre-pubertal and adolescent groups with decease in their mean number. In the adulthood and aged-phase groups, they became shallower and occupied higher position. The collagen fibres were found in the papillary and reticular layers of the dermis. The fibres were sparse and thin in the early weaning period group. After that age, the collagen fibres in the papillary layer were parallel to the surface epithelial, while the fibres in the reticular layer were arranged in the form of bundles distributed parallel and perpendicular to the surface epithelial. The average area of collagen fibres increased in the adolescent and adulthood groups, but decreased in the aged-phase group. The optic density of the elastic fibres decreased in the pre-pubertal and adolescent groups.
Conclusion: Many structural skin changes were observed in the adulthood and aged-phase groups. The epidermis became thinner and flattened, the dermal-epidermal junction became flat, the dermal thickness decreased and the hair follicles became shallower and occupied higher position. The average area of collagen fibres increased in the adulthood group, but decreased in the aged-phase group. All these changes result in impaired wound healing and impaired the formation of scars.