Histology of Basic Tissues (College of Applied Medical Sciences) PDF

College of Applied Medical sciences Department of Medical Laboratory technology Histology of Basic tissue  Histology Is the study of tissues. This involves the examination of the architecture and relationship of the different types of tissues....

College of Applied Medical sciences Department of Medical Laboratory technology Histology of Basic tissue  Histology Is the study of tissues. This involves the examination of the architecture and relationship of the different types of tissues.  Tissue A group of closely associated cells that perform related functions and are similar in structure  Types of basic tissues: Four basic types of tissue…function – Epithelium…covering – Connective tissue…support – Muscle tissue…movement – Nervous tissue…control Epithelium  Epithelium Sheet of cells that covers a body surface or lines a body cavity; also form most of the body’s glands.  Classification of epithelia According to thickness – “simple” - one cell layer – “stratified” – more than one layer of cells (which are named according to the shape of the cells in the apical layer) According to shape – “squamous” – wider than tall – “cuboidal” – as tall as wide – “columnar” - taller than wide  Simple squamous epithelium Description: single layer of flattened cells with disc shaped central nuclei Location: 1- Kidney glomeruli and corpuscles. 2- lung alveoli 3- Lining of heart 4- Lining of blood vessels 5- Lining of serosa- tissue membrane Function: allow passage of material through filtration and diffusion. Secrete lubricant material.  Simple cuboidal epithelium Description: single layer of cube-like cells with large, spherical central nuclei. Location: 1- Kidney tubules 2- Ducts and secretory portions of small glands 3- ovary surface Function: secretion and absorption.  Simple columnar epithelium Description: single layer of tall cells with round to oval cells. Location: A- Non ciliated types: - lines most of digestive system (stomach to anal canal), - gall bladder - excretory ducts of some glands. B- Ciliated types: - Lines small bronchi, - uterine tubes and - some regions of uterus. Function: secretion and absorption.  Pseudostratified columnar epithelium Description: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain goblet cells and bear cilia. Location: Non-ciliated type: In male’s sperm-carrying ducts Ducts of large glands. Ciliated type: Lines trachea, most of the upper respiratory tract. Function: secretion of mucus. Stratified squamous epithelium Description: thick membrane composed of several cell layers: - Basal cells are cuboidal or columnar: active in mitosis - Surface cells are flattened. - In the keratinized types, the surface cells are full of keratin and dead. Function: protection Location: - Non keratinized type: forms the lining of esophagus, mouth and vagina - Keratinized type: form epidermis of skin.  Stratified cuboidal epithelium Rare Description: two layers of cube- like cells. Location: - Largest duct of sweat glands. - Mammary glands. - Salivary glands. Function: protection  Stratified columnar epithelium Description: several layers. - Basal layer usually cuboidal. - Superficial cells is elongated. Location: Small amounts in male urethra. Large ducts of some glands. Function: protection  Transitional epithelium Description: Basal cell are cuboidal or columnar Surface cell are dome shaped or squamous like. Function: stretches easy location: - Lines the ureter, - urinary bladder, - and part of urethra.  Endothelium l i n es th a t h e l i u m s e p it a n d a m o u sse l s l e sq u r y v e p l a to A sim th e c i rc u i o r o f i n t e r t. th e h e a r  Mesothelium lin e s t ha t he liu m s e p i t al m o u p le u r s q ua l a nd p le ar d ia A sim al, p e r ic r ito n e he p e t ie s. t cav i  Glands Definition: an organ that synthesize substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).  Glands Exocrine glands Endocrine glands secrete messenger external secretion molecules onto body surfaces (hormones) which (skin) or into body are carried by blood cavities to target organs; “ductless” glands  Examples of exocrine Examples of endocrine gland products gland products - Many types of mucus secreting glands - Sweat glands of skin - Pituitary glands. - sebaceous glands of - Thyroid gland. skin -Parathyroid gland. - Salivary glands of mouth - Liver (bile) - Pancreas (digestive enzymes) - Mammary glands (milk)  I. Salivary Glands They are exocrine glands that produce saliva. Saliva: is a hypotonic watery secretion containing mucus, enzymes, antibodies and inorganic ions. Types of Salivary Glands A. Major Salivary Glands B. Minor Salivary Glands Major Salivary Glands Secrete 90%of the total volume of the saliva. They are 3 pairs of major salivary glands: Parotid (Serous) Submandibular (a mixed gland, but the Serous secretory units predominate) Sublingual (a mixed gland, but the mucous secretory units predominate) Minor Salivary Glands They are scattered throughout the oral mucosa of the lips, cheeks, palate, tonsils, tongue and tongue papillae. They open directly (or via short ducts) onto the surface of the oral epithelium. They secrete 10% of the total volume of saliva, but 70% of the mucus secreted.  The salivary glands are composed of acini connected to oral epithelium by branching systems of ducts.  Acini are a group of cells surrounding a lumen. There are 3 types of acini: - Serous acini - Mucous acini - Mixed acini Serous acinus Mucous acinus Small diameter Larger diameter narrow lumen Wider lumen Pyramidal cells Cuboidal to columnar cells Nuclei central & rounded Flattened peripheral nuclei Basal Basophilic cytoplasm Cytoplasm is pale & vacuolated (rich in rER), with apical part (due to mucin content) acidophilic (rich in zymogen granules) Produce serous secretions Produces mucous secretions Striat ed Serou muco duct s acini usacin i Mixed Acinus The mucous cells are organized as mucous tubule with the serous cells forming a cap surrounding the mucous part (appear as a crescent cap of basophilic cells called serous demiluneor crescent of Gianuzzi). secrete mixed secretion Mammary gland The mammary gland is made up of two components: the parenchyma and the surrounding stroma. The parenchyma is the tissue performing the special function of the organ, and the stroma is the connective tissue framework of the organ. Mammary Gland A compound tubulo- alveolar glands Stroma (adipose & dense C.T). Breast tissue is divided by thick CT septa (suspensory ligaments) into 12 –20 lobes arranged radially around the nipple Parenchyma:. Each lobe consists of 1- extensively branching ducts (lined by simple cuboidal epithelium surrounded by myoepithelial cells) 2-Empty into one large lactiferous duct. 3- Ducts widen to form lactiferous sinuses (lined by stratified squamous epithelium) before opening in the nipple. Mammar y gland Nipple: is a conical projection of dense CT rich in SM covered by pigmented skin. Contains the openings of large lactiferous ducts Areola: An area of modified pigmented skin surrounding the nipple. Contains large modified sebaceous glands (Montgomery's glands).. Mammary Gland Pregnant & Lactating mammary gland: The following changes occur: - Enlargement of breast size, - Increased pigmentation of nipple & areola - Enlargement of Montgomry glands in the areola The amount of CT septa & fat cells decreases Alveoli (secretary units): develop from ends of ducts; lined by columnar epith. Surrounded by myoepithelial cells