Animal Tissues

1. Animal Tissues By Fayez A. Elmabhouh Department of Biology

2. Introduction • Histology = study of tissues • Tissue = group of cells with similar structure and function • They are classified according to the shape of the cell, size, intracellular matrix. • Four types of human tissues: • Epithelial tissue • Connective tissue • Muscular tissue • Nervous tissue The organ can may consists of one (heart) or combination of these tissues (stomach, skeleton, skin)

3. Four Tissue Types: 1 2 3 4

4. Epithelial Tissues Characterized by: • Their closely connected cells. • Having very little intracellular substance. • Resting on a basement membrane. • Arise from the three germ layers. • No blood vessels enter between its cell but nerves do • Covers body surfaces and forms glands.

5. Basement membrane

6. Embryonic Tissues – all adult tissues are derived from one of three embryonic tissues Ectoderm = “outside skin” gut Mesoderm = “middle skin” Cross section through embryo Endoderm = “inside skin” Animal embryo

7. Classification of Epithelium 1. Covering epithelia. 2. Glandular epithelia.

8. Covering epithelia • The primary function of this type of epithelia is protection. • Covering epithelia classified according to the arrangement of the cell into simple epithelia and stratified epithelia.

9. Simple epithelia • These tissues divided into four types according to the shape of cell and location of nucleus. • Consists of a single layer of cells that are in contact with the basement membrane.

10. 1. Simple Squamous Epithelium: • The cells are flat with smooth edges. • They appear spindle-shaped in cross section • Each cell containing a nucleus in the widest area. • Found in the lining blood vessels, covering serosa

11. Blood vessel

12. Serosa

13. Simple Squamous Epithelium Simple Squamous Epithelium Bowman’s capsule

15. 2. Simple Cuboidal Epithelium • The cells in this epithelium are square-shaped in cross section. • Have central and round nucleus. • Lining the kidney tubules and Follicles of thyroid gland

16. Follicles of thyroid gland

18. Simple Cuboidal Epithelium cells single layer of cube shaped cells; large nuclei

19. 3. Simple Columnar Epithelium • Built of long pillar-shaped cells. • Containing an oval nucleus. • Ciliated: Bronchioles • Non Ciliated: lining the ileum

23. 4. Pseudo-stratified Epithelium • Single layer of cells which rest on a basement membrane but do not all reach to the free surface of the epithelium. • Their nuclei found at different levels giving the a false stratified appearance. • Cells that reach the surface carry cilia at their free ends. • Lining the trachea.

27. Keratinized: the epithelium is covered with keratin layer which is formed by the dead squamous cells (horny layer) Skin. • Non- keratinized: esophagus

28. Non- keratinized

30. Keratinized: Skin • Epidermis (Stratified Squamous Epithelium) • Dermis

32. Transitional- stratified • Found in the urinary tract (urinary bladder) • Rest on a non clear and non wavy basement membrane. • Its superficial cells are cuboidal in shape, and may contain 2 nuclei. • The basal cell layer is formed of high cuboidal cell. • The intermediate layer are polyhydral cells. • Empty • Full, the cell change into to squamous cell

36. Glandular Epithelium • The cells are specialized in secretion and thus form glands. • Formed from collections of Epithelial cell • Glands with ducts are termed exocrine • Glands without ducts are termed endocrine

37. Exocrine Glands • Unicellular: formed of single cell present in the respiratory tract and intestinal tract

39. Multicellular gland • Made of many cells and each consist of a secretary portion and duct. • They are either tubular, alveolar in form and may be simple or compound.

40. Simple tubular glands • In the digestive glands, stomach, Large intestine

41. Simple alveolar gland • Form of a flask with a round secretary portion and a narrow tubular duct. • Mucous and sebaceous gland skin

43. Compound tubular glands

44. Compound alveolar gland • Parotid gland