Changes

NOTE: The objective of this first exercise is merely to gain an awareness of the varieties of cell sizes, cell shapes, cell types, cell staining characteristics and cell organelles or inclusions. You are not expected, at this time, to become familiar with the over-all structure of the tissues and organs where these cells are located.

On slide 25, Spinal Cord (Thionin) find under low power the cell bodies of multipolar neurons located in the two anterior horns of the gray matter (if the slide is held towards the light, the gray matter appears H-shaped). With medium power, identify a cell body containing a large pale nucleus and a darkly stained nucleolus. Study this cell under high power. The irregular, granular-like, basophilic staining masses within the cytoplasm are called Nissl bodies. They consist of free ribosomes and granular endoplasmic reticulum.

On slide 73, Spinal Ganglion (silver) identify the large cell bodies of the ganglion cells associated with the sensory root of spinal nerves. The cell bodies of these unipolar neurons range in size from 15μm to 100μm. Compare a number of ganglion cell bodies for size differences. The centrally located nuclei stain palely and appear as clear spaces in the middle of the granular cytoplasm. With careful observation you will see nuclei of much smaller cells immediately surrounding the cell bodies of the ganglion cells. These represent satellite cells. Note how much smaller they are than the nuclei of the ganglion cells.

On slide 149, Liver (H&E) observe that the hepatocytes (liver parenchymal cells) appear to be arranged as rows or cords of cells. Actually the tridimensional arrangement of these cells is in cellular sheets or plates which are separated by blood-filled spaces called sinusoids. Red blood corpuscles may be seen in some of the sinusoids. Note that cell boundaries can be distinctly seen between many of the liver cells. The polyhedral- shaped hepatocytes have round, centrally located nuclei containing one or more nucleoli and scattered clumps of chromatin. Binucleated hepatocytes can be found. Note the granularity of the eosinophilic staining cytoplasm

Slide 154, Pancreas (H&E) has cells which distinctly exhibit a difference between basophilic regions and acidophilic regions. After studying the cells with medium power, turn to high power to complete your study. Observe that the cell boundaries are indistinct. Note that the cytoplasm in the basal region of the acinar cells is basophilic. Here the ribonucleoproteins associated with rough endoplasmic reticulum and the large numbers of mitochondria are sufficiently dense to stain with the basic dye. Note, however, the red staining of the apical half of the acinar cells. This acidophilic staining cytoplasm contains numerous secretory granules that stain brightly with the eosin stain. The nuclei are basophilic staining as are the nuclei of all cells. Observe that the nuclei are characteristically located in the basal one-third of the cell. Nucleoli may be seen in many cells.

On slide 2, Trachea (H &E) identify the cilia on the tall cells of the pseudostratified columnar epithelium that line the lumen of the trachea. Each cilium is derived from a basal body, represented here in aggregate by the dark lines where the cilia attach to the cell. In some regions of this tissue the cilia are absent or the entire epithelium is missing. This is artifact.

On slide 89, Skeletal Muscle (H&E) identify muscle fibers cut in longitudinal section. Under high power note the striated appearance of the muscle cells. Although not readily visible, the cytoplasm of these cells contains myofibrils, the contractile elements of the cell. The arrangement of these myofibrils and their subunits, the myofilaments, impart the striated appearance to the muscle fibers.

On slide 31, Ileum (H &E) identify with low power the villi projecting from one side of the tissue. With high power identify the tall cells (simple columnar cells) which cover these villi. On the free surface of these cells can be seen a dense line representing the striated border. This border consists of cytoplasmic processes termed microvilli that greatly increase the absorptive area of the small intestine. In light microscopy, the microvilli appear vertically striated so these projections form a “striated border.”