Essentials of light microscopy Connective tissue

Instructions Turn on the light. Lower the stage all the way using the coarse focus knob. Start with the 4x objective. Put the slide on the stage, held in place by the little spring clip. Make sure both the slide and the stage are dry. Move your sample until you can see that the light is shining through it. Do this before you even put your eyes to the oculars. Look through the scope and focus. Use the coarse focus knob at first, until the image is more or less in focus; then switch to the fine focus. Look at the whole slide on the lowest power, so you get an overview before you switch to higher magnification. Adjust the light. Not too bright, not too dim. Adjust the oculars. Don't use the 100x! Switch to the 10x objective. If the slide is in focus with the 4x, it should be more or less in focus when you switch to the 10x. A slight adjustment with the fine focus knob should get it just right. If you lose the focus and can't see your specimen at all, go back to the 4x and start again. Switch to the 40x objective if you want to see more detail. It's up to you to decide what magnification is best for what you want to see. When you want to look at a new slide, switch back to the 4x before changing slides. When you're done with the scope, switch to the 4x, turn the light all the way down before turning it off, and bring the stage all the way down. Don't put away the scope with a slide still on the stage! Only one slide is out of the box at the moment. Do not remove more! At the end of lesson, the box with slides is checked in your presence before you leave your place

Tissues Connective tissue connective tissue proper cartilage bone Epithelial tissue Muscle tissue Nerve tissue types of the connective tissue

Connective tissue proper

Connective tissue cells Fixed cells fibroblasts and fibrocytes reticular cells pigment cells undiferentiated mesenchymal cells adipocytes /fat cells/ univacuolar multivacuolar Wandering cells /mobile/ histiocytes /makrophages/ heparinocytes /mast cells / plasma cells leukocytes lymphocytes eosinophils neutrophils responsible for production extracellular components involved in tissue reaction to injury, defensive reaction

Fibrocytes spindle-shaped, long processes, ovoid pale nucleus, basophilic cytoplasm, the components of the ground substance, collagen, elastic and reticular fibres are synthesised by cells of the c.t. - the fibroblasts /fibrocytes/.

Reticular cells X not RETIKULOCYTES Reticular cells are usually larger than an average fibrocyte. They are the "fibrocytes" of reticular connective tissue and form a network of reticular fibres, for example, in the lymphoid organs. Some of them are able to phagocytose. Their nuclei are typically large and lightly stained.

Pigment cells long branched cytoplasmic projections melanin granules derived from neural crest /neuroectodermal origin/

Adipocytes univacuolar multivacuolar are present in brown adipose tissue – embryo, child to 3 years large – up to 100 µm, spherical shape

Macrophages /histiocytes/ They have irregular shape, small hyperchromatic /dark/ nucleus, numerous secondary lysosomes /phagocytic vacuoles/

Mast cells /heparinocytes/ The cytoplasm of mast cells is filled by numerous granules. Mast cells discharge the contents of these granules if they come in contact with antigens. The most prominent substances contained in the vesicles are heparin and histamine. They increase blood flow and the permeability of the vessel walls.

Mast cells

Plasma cells B-lymphocyte plasma cells are lymphocytes which produce antibodies to accommodate the necessary organelles for this function the size of the cytoplasm increases dramatically and the cells become basophilic /GER/ nucleus is ovoid, located peripherly, clumps of peripheral heterochromatin – like a wheel or clockface

Extracellular substance collagen fibres

collagen fibres in LM AZAN HE HES

reticular fibres

reticular fibres lien /spleen/

elastic fibres

elastic fibres aorta

Ground substance is found in all cavities and clefts between the fibres and cells of connective tissues glycosaminoglycans /GAGs/ hyaluronic acid chondroitin 4-sulfate / chondroitin 6-sulfate/ dermatan sulfate heparan sulfate proteoglycans /protein core to which GAGs are covalently bound/ - aggrecan, syndecan, fibroglycan glycoproteins – fibronectin, laminin, osteonectin, osteopontin, chondronectin..

Connective tissue - types Mesenchyme Mucous connective tissue - occurence: umbilical cord, dental pulp, iris of eye Loose /areolar/ connective tissue wide spread, within various parenchymal organs /kidney, glands,../, parts of mucosa, submucosa of hollow organs../ Dense connective tissue Irregular arranged – dermis, capsules of organs, periosteum, fasciae.. Regular arranged – tendons, ligaments, aponeuroses.. Elastic connective tissue – vocal cords, large arteries.. Reticular connective tissue – lymphatic organs, bone marrow Adipose tissue

Mesenchyme Components: mesenchymal cells, fluid ground substance, reticular fibers

Mucous connective tissue Wharton's jelly Occurence: dental pulp, iris of eye

Loose connective tissue gullet

Loose connective tissue

Dense connective tissue - regular

Dense connective tissue - irregular sclera

Dense connective tissue - irregular

Elastic connective tissue aorta

Reticular connective tissue

Adipose tissue