5/20/2023 0 Comments Xsection of muscle![]() The lighter H zone which bisects the A band.You should recognize: (Using your microscope and glass slides may help to see these fine structures) A sarcomere consists of the structures between two Z lines. Cross striations can be seen, and are due to the structure of the sarcomere.Note that each cell contains large numbers of nuclei. Peripheral position of the elongate nuclei just inside of the sarcolemma (plasma membrane).This is why it is important to look at other features of the cell to determine what exactly it is. Cells with peripheral nuclei that are cut at an angle can appear to have centrally located nuclei. Why? Again the answer to the question is in the plane of section. You might see occasional nuclei which appear to be centrally located, but aren’t. Be sure you can identify the borders of the muscle cell.These cells are very long you cannot see their ends. Nonbranching, cylindrical shape of the cell (also referred as muscle fiber).In longitudinal sections of skeletal muscle ( Slide 58, odd-numbered slide boxes), observe the following : 058T Skeletal muscle H&E cross Webscope.058Thin skeletal muscle H&E longitudinal Webscope.058Lex Skeletal muscle H&E longitudinal Webscope.058L skeletal muscle H&E longitudinal Webscope.You should be able to recognize each type of muscle in both planes of section. In contrast, cardiac and smooth muscles are called involuntary muscles because their contractions are either spontaneously generated or are under the control of the autonomic nervous system.Įach of these three types of muscle has a characteristic appearance in both cross and longitudinal sections. Skeletal muscle is also called voluntary muscle, because its contraction is under conscious neural control. Such an arrangement is not seen in smooth muscle cells. This regular arrangement imparts a cross-striated (or striped) appearance. Skeletal and cardiac muscle cells are called striated muscle because of the very regular arrangement of their intracellular contractile units, sarcomeres, at the light microscope (LM) and electron microscope (EM) levels. There are three major types of muscle, and their structure reflects their function. Be familiar with the regenerative potential of each muscle type.Understand where stem cells are located in skeletal muscle and be able to identify their location at both the light and EM levels.Know the structural elements that harness muscle contraction (i.e., the shortening of myofibrils) to the movement of a body part (i.e., via connection to bone) as well as the mechanism by which muscle cells (skeletal, cardiac and smooth muscle) contract.Be able to describe and understand the structural basis of muscle striation at the light microscope and EM levels and the molecular level.Be able to name and to identify the three types of muscle at the light and electron microscope levels, including distinctive features of each, such as the intercalated discs of cardiac muscle.
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