2. Skin 皮肤 Department of Histology and Embryology Medical college in Three Gorges University

3. hair sebaceous gland sweat gland Nails Ⅰ.Skin ： Epidermis Dermis Ⅱ.Skin Appendages

4. Skin Epidermis Dermis Keratinocytes Nonkeratinocytes Papillary Layer Reticular Layer

6. Function of skin 1 、 Protect organism from impact and friction injuries 2 、 receptor organ 3 、 participate in thermoregulation 4 、 secreting the sweat 5 、 Absorption

8. stratum lucidum Langerhans Cells Merkels Cells strstum basale stratum spinosum statum granulosum stratum corneum Melanocytes Keratinocyte Ⅰ. Epidermis Nonkeratinocytes

9. Stratum Basale Stratum Spinosum Stratum Granulosum stratum corneum

10. Stratum Spinosum Stratum Granulosum stratum corneum Strstum basale

11. ⑴ stratum basale: Stratum Germinativum The stratum basale consists of a single layer of basophilic columnar or cuboidal cells resting on the basement membrane at the dermal-epidermal junction. Hemidesmosomes,found in the basal plasmalemma,help bind these cells to the basal lamina.

12. Mitotic activity

15. EM ： RER,ribosome, etc, organlles. the cells contain the intermediate keratin filaments about 10nm in diameter.

16. （ 2 ） stratum spinosum The stratum spinosum consists of polygonal,or slightly flattened cells with a central nucleus and a cytoplasm whose processes are filled with bundles of keratin filaments. These cell bear many spines and there are some desmosome between the spines. Cohesion.

21. （ 3 ） Stratum granulosum The strstratum granulosum consists of 3---5 layers of flattened spindle cells whose cytoplasm is filled with coarse basophilic granules called keratohyalin granules. The proteins of these granules contain a phosphorylated histidine-rich protein as well as proteins containing cystine.

22. Stratum Spinosum Stratum Granulosum stratum corneum strstum basale

25. （ 4 ） Stratum Lucidum More apparent in thick skin,the stratum lucidum is a translucent,thin layer of extremely flattened eosinophilic epidermal cells. The organelles and nuclei are no longer evident and the cytoplasm consists primarily of densely packed keratin filaments embedded in an electron-dense matrix. Desmomes are still evident between adjacent cells.

26. Stratum Lucidum

27. （ 5 ） stratum corneum The stratum corneum consists of 15-20 layers nonnueleated keratinized cells whose cytoplasm is filled with birefringent filamentous scleroprotein, keratin. These cell have not the exact limit and acidophilic cytoplasm.

29. Stratum Spinosum Stratum Granulosum stratum corneum strstum basale

30. keratin

32. 2 、 Nonkeratinocytes （ 1 ） melannocyte （ 2 ） Langerhans cell （ 3 ） Merkel cell

33. （ 1 ） melannocyte Melanin is synthesized in the melanocyte.

34. Melanocytes

36. （ 2 ） Langerhans cell Langerhans cells are derived from bone- marrow. They are Star-shaped cells found mainly in the stratum spinosum of the epidermis. H-E: Dark stained nuclei with light cytoplasm.

39. （ 3 ） Merkel cell Merkel cell generally present in the thick skin of palms and soles

40. 真皮

41. Ⅱ.Dermis 1 、 papillary layer ： The thin papillary layer is composed of loose connective tissue. fibroblasts and other connective tissue cells such as mast cells and macrophages are present. The papillary layer is so because it constitutes the major part of the dermal papillae. Capillary, Tactile Corpuscles

42. 表皮 乳头层 网状层

44. 2 、 reticular layer ： The reticular layer is thicker, composed of irregular dense connective tissue and therefore has more fibers and fewer cells than does the papillary layer. The dermis contains a network of fibers of the elastic system.

45. epidermis Papillary layer Reticular layer dermis

46. sweat gland

47. hypodermis

48. Ⅲ.Skin Appendages hair sebaceous gland sweat gland nail

49. (1) 、 hair 1 、 structure of hair Epithelium follicle Connective tissue:dermis Epidermal invagination, hair follicle hair shaft hair root hair follicle

50. Termical dilation of hair follicle are called hair bulb, the invagination is called hair papilla. The epithelium cells covering this dermal papilla referred to germinal matrix of hair. In the hair papilla there are rich in capillaries and nerving ending.

51. Hair shaft Hair root Arrector pili muscle Hair follicle

52. Hair follicle

53. hair bulb hair papilla

55. （ 2 ） sebaceous gland Acini duct Secreting unit

57. sebum

58. The acini consist of a basal layer of undifferentiated flattened epithelial cells that rest on the basal lamina.These cells proliferate and differentiate filling the acini with rounded cells containing increasing amounts of fat droplets in their cytoplasm. The product of this process is sebum, the secretion of the sebaceous gland which is gradually moved to the surface of the skin

59. （ 3 ） Sweat gland Secreting portion: simple cuboid cells or pyramidal cells, myoepithelial cell which help to discharge the secretion. Duct: present in the dermis. They are lined by stratified cuboidal epithelium