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 types of the connective Epithelial tissue tissue Muscle tissue Nerve tissue Connective tissue proper Connective tissue cells
Fixed cells Wandering cells /mobile/ fibroblasts and fibrocytes histiocytes /makrophages/ reticular cells heparinocytes /mast cells / pigment cells plasma cells undiferentiated mesenchymal cells leukocytes adipocytes /fat cells/ lymphocytes univacuolar eosinophils multivacuolar neutrophils
responsible for production extracellular involved in tissue reaction to components 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 B-lymphocyte Plasma cells
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