Thin Skin
•Epidermis has three layers:
1. Stratum basale or stratum germinatum--is deepest where cell proliferation takes place, made of columnar cells.
2. Stratum spinosum/prickle cell layer several layers of closely packed polyhedral cells joined by desmosomes.
3. Stratum corneumcdosely packed squames of keratin. Thinner than the thick skin.
•Epidermis made up of two type of cells-keratinocytes and non-keratinocytes (melanocytes, Langerhans cells, Merkel cells).
•Dermis consists of papillary dermis and reticular dermis.
Papillary dermis is superficial, with loose connective tissue containing blood vessels and sensory nerve endings. It projects into the epidermis forming papillae
Reticular dermis with dense connective tissue with bundles of collagen fibers
•Skin Appendages
Hair follicle- invagination of epidermis into dermis containing the cornined hair. Arranged obliquely at an angle to epidermis.
Sebaceous gland-associated with hair follicle.
Arrector pili muscle-bundle of smooth muscles wnich is arranged obliquely.connecting the hair follicle with Danillamw d
Sweat glands and ducts seen.
Thick Skin
•Epidermis has five layers:
1. Stratum basale or stratum germinatum-is deepest where cell proliferation takes place, made of columnar cells.
2. Stratum spinosum/prickle cell layer several layers of closely packed polyhedral cells joined by desmosomes.
3. Stratum granulosum-three to four layers of flattened cells containing keratohyalin granules.
4. Stratum lucidum-dead clear cells filled with keratin.
5. Stratum corneum-closely packed squames of keratin.
•Epidermis made up of two type of cells-keratinocytes and non-keratinocytes (melanocytes, Langerhans cells, Merkel cells)
•Dermis consists of papillary dermis and reticular dermis.
Papillary is superficial, with loose connective tissue containing biood vessels and sensory nerve endings. It projects into the epidermis forming papillae.
Reticular dermis with dense connective tissue with bundles of collagen fibers.
•Skin appendages: Hair follicles, sebaceous gland, arrector pili muscle are absent.
•Sweat gland is present
•Thick skin found in palms and soles.