Simple columnar with brush border Mohini Kaul Histology writes about gall bladder histology - "The epithelium consists of a single layer of tall columnar cells. Each cell has basal oval shaped nucleus, and an apical pa having a brush border due to the presence of microvilli.""Columnar epithelium with a striated border is seen most typically in the small intestine, and with a brush border in the gall bladder." - Inderbir Singh Histology 4/e, p 45There are 4 types of tissues in the bodyEpithelial tissueConnective tissueMuscular tissueNervous tissueEpithelial tissue covers the outer surface of the body and the luminal surfaces of cavities within the body, along with lining the ducts and secretory elements of glands.Classification of epitheliumSimple epithelium - consisting of only one layer of cellsMultilayereda)Stratifiedb)Transitional3.Pseudostratified - single layered, but give the appearance of multilayered, because of the arrangement of the nuclei at different levels.Simple Epitheliuma)Squamous ?- The cells are flattened, their heights being very little as compared to their width.- found in- Alveoli of lungs- Endothelium of blood vessels & lymphatics- Mesothelium of serous membranes (pleura, pericardium, peritoneum)- Endocardium of heab)Cuboidal epithelium- Height is almost same as the width- found in- Follicles of the thyroid gland- Germinal epithelium of ovary- Ducts of many glands- Proximal convoluted tubules of the kidneys (here the cuboidal epithelium has brush border)c) Columnar epithelium- The cells are taller than their widthIt is fuher classified according to the nature of the free surfaces of the cells.i) Simple columnar epithelium- No paicular specialization- found in mucous membrane of stomach and large intestineii) Columnar cells with brush border- Here the cell surface has microvilli. The microvilli are visible only with electron microscope. With light microscope the microvilli appear as brush border.- found in- Gallbladder- Small intestineiii) Ciliated columnar epithelium- The cell surface bears cilia. The movement of the cilia helps propel the fluid.- found in- Most of the respiratory tract- Fallopian tubes- Efferent ductules of testisStratified epitheliuma)Stratified squamous epitheliumThis type of epithelium is made up of several layers of cells. The deepest layer is columnar and in proceeding towards the surface, the cells become increasingly flattened. So that the surface consists of squamous cells and middle layer consists of cuboidal and polyhedral cells.i) Stratified squamous keratinizedeg. skinii) Stratified squamous non-keratinizedeg. esophagus, oral cavity, vagina, corneab) Stratified cuboidal epitheliume.g. secondary ovarian folliclesc) Stratified columnar epithelium- moderate sized ducts of glands e.g. salivary glands- transition zone of epithelium of anal canal- male urethra (membranous & penile pas)Transitional epithelium- It is a multilayered epithelium that is capable of considerable distension.- found in ?- Renal pelvis and calyces, the ureter, the urinary bladder, and pa of the urethra- As it is confined to the urinary tract, it is also k/a urotheliumPseudostratified This is a simple columnar epithelium, only one cell thick but cells are of varying height. Some cells are sho, not reaching the surface, others are tall columnar and few are goblet cells. Thus their nuclei lie at different levels giving pseudo appearance of many layers.- found in- Sensory epithelium of olfactory area- Trachea and large bronchi- Pas of auditory tube- Ductus deferens