Figure 1: Skin of the different age groups stained with H&E stain showing the stratum corneum (SC) of the epidermis (E), hair follicles (HF) within the dermal layer (D) and a layer of skeletal muscle (M) beneath the skin. Note: hair follicles (HF) and fat sells (*) within the hypodermis (H). (a) The skin of a ten day old rat. Note absence of the fat cells of the hypodermis (H&E 100X). (1b) Higher magnification of the previous figure showing the stratum corneum (SC), cells of the stratum basale (thick arrow), cells of stratum spinosum (thin arrows) and keratohyalin granules (arrowheads) of the stratum granulosum of the epidermis. Cortex (C), medulla (M), outer cortex sheath (ORS) and inner cortex sheath (IRS) of the hair follicles (HF) (H&E 400X). (c) the skin of a twenty day old rat. (H&E 100X). (e) the skin of a two month rat. (H&E 100X). (E and f) the skin of a six month old rat (H&E 100X). (g) the skin of a one year old rat. Note decrease number of hair follicles which occupied a higher position in the dermis (H&E 100X). (h) Higher magnification of the previous figure showing atrophy of the hair follicles and absence of the layers of the stratum corneum (H&E 400X). (i) the skin of a two year old rat where the epidermis is thin and flattened. Also, the hair follicles decreased and occupied a higher position in the dermis (H&E 100X).