Electron Microscopy

Answer 1

A lymphocyte in late prophase. The nuclear envelope has begun to disappear and is evident in only a few places. (Arrow).
CG = ChromatinGranules; M = Mitochondria; RER = Rough Endoplasmic Reticulum
x 24,000

Answer 2

A lymphocyte in metaphase with the chromosomes lining up at the equatorial plate. The plane of section does not include the spindle fibers. 1 = Endoplasmic Reticulum; 2 = Mitochondria.

Answer 3

Part of a cell. The nucleus is located at the lower right hand side of the micrograph. Dense chromatin (heterochromatin)(1) is distributed alongthe nuclear side of the nuclear envelope except in regions of the nuclear pores (2). 3 = Euchromatin; 4 = Smooth Endoplasmic Reticulum; 5 = Golgi Body

Answer 4

High magnification micrograph with nucleus on the left and cytoplasm on the right. A nuclear pore is marked by the arrow. Note the absence of heterochromatin at the site of the pore. N = Nucleus.

Answer 5

Pinocytosis is an endothelial cell. The vessel lumen is to the upper right and the underlying connection tissue is to the lower left. Notethe thin gray (electron dense) line of the basal lamina immediately below the cell. There are several unlabeled vesicles forming at the luminal surface of the call.
1 = Vesicles open to the outside of the cell facing the extracelluar matrix; 2 = Partially enclosed vesicle just inside the plasma membrane; 3 = Vesicle completely contained within the cytoplasm of the cell

Answer 6

Part of a cell showing a centriole (C) cut transversely. Note the triplet arrangement of microtubules cut in croos-section.
GA = Golgi Apparatus (Body); PR = Polyribosomes (Polysomes); NS = Perinuclear Space (of the nuclear envelope)

Answer 7

Part of a lymphocyte. The nucleus is at the upper right side of the micrograph. It is surrounded by a nuclear envelope and contains euchromatin and heterochromatin. The cytoplasm contains some rough endoplasmic reticulum (RER) and numerous polysomes (polyribosomes). There is a portion of a mitochondrion at the upper left edge of the micrograph. Note that the lumen of the RER is continuous with lumen of the nuclear envelope (arrow).

Answer 8

Rough endoplasmic reticulum arranged in stacks in a pituitary cell. Ribosmes (arrows) are associated with the membrane of the endoplasmic reticulum. 1 = Mitochondrion; 2 = Secretory Granule

Answer 9

Cytoplasmic organelles of a renal collection duct cell.
TL = Tubular Lumen; MV = Microvilli on cell surface; M = Mitochondrion; PR = Polyribosomes (Polysomes); GA = Golgi Apparatus (body); IS = Intercellular Space; note the interdigitations of the cell membranes are between the two cells. (lower right); Although not labeled, note (at the lower right of the micrograph) that there is a thin gray line of the basal lamina just external to the cell membrane.

Answer 10

High magnification of a network of smooth endoplasmic reticulum (SER). Unlike rough endoplasmic reticulum, which usually occurs in flat sheets, the SER is comprised of interconnected tubules (1).
2 = Mitochondrion; 3 = Free Ribosomes, seen either singly or as polyribosomes (polysomes)

Answer 11

Detail of Golgi Apparatus (body)
1 = Cis, forming, convex face; 2 = Trans, maturing, concave face; 3 = Saccules; 4 = Vesicles budding from saccules; 5 = Centrioles

Answer 12

Details of mitochondria.
1 = External envelope; 2 = Cristae; 3 = Matrix (the more electron-dense material); 4 = Granules within the matrix

Answer 13

Large lipid droplets (LD) are seen within a cell in the deeper parts of the adrenal cortex. The lipid matrix has been removed during tissue preparation.
M = Mitochondria (with tubular cristae are typical of steroid producing cells); SER = Smooth Endoplasmic Reticulum

Answer 14

Detail of secondary lysosome with engulfed material within it.
1 = Limiting membrane; 2 = Matrix; 3 = Partially digested material

Answer 15

Glycogen particles within a liver cell. When the particles occur in clusters (1), they are known as alpha-particles. Single glycogen particles (2) are called beta-particles. Compare the size of glycogen particles with ribosomes seen lining the endoplasmic reticulum (3). 4 = Smooth endoplasmic reticulum.

Answer 16

Organelles found in cell cytoplasm; SV = Secretory Vesicle; GA = Golgi Apparatus; M = Mitochondrion

Answer 17

High magnification of myelin sheath (1) Surrounding a nerve fiber in a peripheral nerve. Within the fiber can be seen: 2 = Microtubules; 3 = Neurofilaments Such a nerve fiber might be either an AXON of a multipolar motor neuron or the DENDRITE of a sensory pseudounipolar neuron.

Answer 18

Epithelial cells showing a large bundle of tonofilaments (1) in one of them. 2 = Desmosomes along the opposing cell membrances of two cells; 3 = Mitochondrion; 4 = Nucleus of the lower cell.

Answer 19

The figure on the left (fig. 4) shows a longitudinal section through an Initial Axon Segment. Prominent features include: A. Scattered Ribosomes; B. Fascicles of Microtubules; C. Mitochondria; D. Occasional Neurofilaments

Figure 5 (on the right) is a transverse section through a dendrite of an anterior horn cell. The cytoplasm contains abundant microtubules and neurofilaments. It shows microtubules, Neurofilaments and Neuroglial Filaments (X211,000). The inset at the upper right shows bundles of cytoplasmic filaments in an astrocyte (X75,000).

Answer 20

Apical Region of Epithelial cells, showing Cilia cut longitudinally.
1 = Cell Membrane; 2 = Central Microtubules; 3 = Peripheral Microtubules; 4 = Basal Body; 5 = Rootlets; The Densities of some cell junctions can be seen in the upper right quadrant of the photo, along the cell membranes of the two opposing cells; 6 = Microvilli, for comparison of size with cilia

Answer 21

Cross-cuts of cilia, showing the typical 9 + 2 arrangement of microtubules within the cytoplasm: A ring of nine doublets plus two singles in the center. Ordinary cell membrane (arrow) completely covers each cilium.

Answer 22

Several longitudinally cut smooth muscle cells from an intra-renal artery. Each cell is surrounded by a gray basal lamina (1). 2 - Myofilaments (mainly actin), often attached to electron dense plaques. The “hairy” look is typical of smooth muscle.; 3 - Mitochondria; 4 - Pinocytotic vesicles along plasma membrane. These, too, are typical of smooth muscle.

Answer 23

Junctional complex between two adjacent epithelial cells in the lining of the small intestines.
1 = Tight junction (zonula occludens) in which the outer leaflets of the plasma membranes have fused; 2 = Intermediate junction (zonula adherens) in which the plasma membranes are separated by a space of approximately 200 Å (20nm); 3 = Desmosome (Macula Adherens) in which cell membranes are again separated by about 200 Å (20nm), but the inter-cellular space contains electron-dense material. Within the cytoplasm of each cell there is a dense plate-like structure (see arrow). To the right are microvilli lining the luminal surface of the cells. The trilaminar appearance of the plasma membrane (2 thin, dark lines with pale in between) covering each microvillus can be seen clearly in several places. Notice also the microfilaments extending from the bases of the microvilli, into the terminal web area of the cell cytoplasm.

Answer 24

Desmosome (Macula Adherens) between two cells
1 = Trilaminar cell membrane; 2 = Intercellular density; 3 = Plate-like cytoplasmic thickening

Answer 25

Several desmosomes (see arrows) lying along the corrugated intercellular border between two cells (one cell is above and the other below in the field). Near the Desmosome at the extreme right of the picture you can see two parallel lines representing the two apposing cell membranes, with about 150 Å space between them. Within the Desmosome note the characteristic heavy, dark densities of the cell membranes and the thin dark line lying in the intercellular space. Note also the many strands of tonofilaments scattered in the surrounding cell cytoplasm, and the way some of them are anchored in the Desmosomes.

Answer 26

Basal Lamina (1) of Epithelial cell; 2 = Reticular fibrils in ground substance (a condensation of this area just deep to the basal lamina contributes to the “basement membrane” often seen in light microscropy); 3 = Mitochondrion

Answer 27

mmunocytochemical analysis of Fibroblasts for Actin (Panel A) and Microtubules (Panel B).

Answer 28

Microvilli lining the luminal surface of absorptive epithelial cells in the small intestine. Within each microvillus is a system of straight actin filaments (1) which extend into the main mass of the cytoplasm to terminate as rootlets (2) in the terminal web area. Although are not cosidered to be motile, in the way that cilia are, it has recently been shown that the contractile protein, myosin, is distributed along the rootlets. Notice that at this magnification the cell membrane extending up over each microvillus appears to be trilaminar, with a pale center between two lines. Passing through the middle of the photo is a tortuous intercellular space between two cells. Just below the microvilli the densities of a junctional complex can be seen, consisting of: 3 = A tight junction (zonula occludens); 4 = An Intermediate junction (zonula adherens); 5 = A Desmosome (Macula Adherens) These three densities, taken together, equal the so-called “terminal bar” of light microscopy. The arrow points to a region where the trilaminar appearance of the plasma membrane is cleary seen.

Answer 29

Epithelial cells showing a large bundle of tonofilaments (1) in one of them. 2 = Desmosomes along the opposing cell membrances of two cells; 3 = Mitochondrion; 4 = Nucleus of the lower cell

Answer 30

Apical Region of Epithelial cells, showing Cilia cut longitudinally.
1 = Cell Membrane; 2 = Central Microtubules; 3 = Peripheral Microtubules; 4 = Basal Body; 5 = Rootlets; 6 = Microvilli, for comparison of size with cilia.
The Densities of some cell junctions can be seen in the upper right quadrant of the photo, along the cell membranes of the two opposing cells.

Answer 31

Several longitudinally cut smooth muscle cells from an Intra-Renal Artery. Each cell is surrounded by a gray Basal Lamina (1). 2 - Myofilaments (mainly actin), often attached to electron dense plaques. The “hairy” look is typical of smooth muscle.; 3 - Mitochondria; 4 - Pinocytotic vesicles along plasma membrane. These, too, are typical of smooth muscle.

Answer 32

Striated muscle cut in cross-section and showing thick (myosin) and thin (actin) filaments within myofibrils. Between myofibrils are seen: >M - Mitochondria; Sr - Sarcoplasmic reticulum; G - Glycogen

Answer 33

High magnification of an intercalated disc between the ends of two cardiac muscle cells. Both Desmosomes (1) and fasciae adherentes (2) are identified. Notice Mitochondria and glycogen particles lying between Myofibrils, as usual.

Answer 34

Branches of two cardiac muscle cells which have met to form a junctional complex, or intercalated disc (arrow). 1 - Mitochondria packing the cell cytploasm between myobrils (notice the thin gray line of basal lamina following along every.outer cell membrane).

Answer 35

Low magnification of cardiac muscle showing the charaacteristic branching of the cells (arrows). Lined up between Myofibrils in the cell cytoplasm are numerous Mitchondria (1). Within the Myofibrils are the typical Sarcomeres (2), extending from Z line to Z line. At (3) is an intercalated disc, extending irregularly across the whole cell width.

Answer 36

Skeletal Muscle cell. N = nucleus at periphery of cell; A = A band; I = I band; Z = Z band; H = H band; M = Mitochondria, lying in the Cytoplasm between Myofibrils. From Z line to Z line = one Sarcomere.

Answer 37

Several Myofibrils running longitudinally through skeletal muscle cell (from top to bottom of this picture). Between individual Myofibrils lie the Mitochondria (M) and Glycogen (G) of the Cytoplasm. WIthin each myofibril are the typical striations: A = A band; I = I band; Z = Z line; H = H band. The banding is formed by the arrangement of myosin and actin filaments.

Answer 38

A. Micrograph of a longitudinal section of skeletal muscle, passing tangential to a myofibril. Observe the longitudinal tubules of the sarcoplasmic reticulum and two transversely oriented triads at the level of the A-I junctions. Glycogen particles are present among the sarcotubules.

Answer 39

B. Longitudinal section of muscle that has been immersed in peroxidase. The dense-reaction product of the peroxidase is present in the lumen of the tubules (demonstrating continuity of the lumen with the extracellular space.

Answer 40

Low Magnification electron micrograph of the celebral cortex. To the left is the cell body of a neuron, showing: 1 = its nucleus; 2 = lysosome-like bodies in the cytoplasm.

Also identified are: 3 = myelinated nerve fibers; 4 = dendrites; 5 = dendritic spines which are making contact with axon terminals at synapses (see also arrow).

Answer 41

A low magnification micrograph of a nerve cell in the cerebellum. The cell is relatively large and has a pale staining nucleus (1) which has very little heterochromatin. At the top of the micrograph are several small neurons (2). A portion of the neuropil with processes is seen at the bottom (3). Several synapses (arrows) can be identified.

Answer 42

Two neuronal cell bodies in the cerebral cortex. The nuclei (1) are sometimes indented (arrow) and have prominent nucleoli (2). In the perikarya are: 3 = mitochondria; 4 = golgi bodies; 5 = rough endoplasmic reticulum; 6 = lysoomes.

Answer 43

Higher magnification of the cytoplasm of a nerve cell, showing: 1 = Golgi body; 2 = profiles of rough endoplasmic reticulum; 3 = mitochondria; 4 = the nucleus. Some of the Mitochondria border the cell’s plasma membrane and are separated from it by sub-surface cisternae (arrow).

Answer 44

Higher magnification of the perikaryon in a neuron of the cerebal cortex, showing: 1 = Golgi body; 2 = mitochondria; 3 = rough endoplasmic reticulum; 4 = microtubules; 5 = numerous polyribosomes; 6 = the nucleus.

Answer 45

Higher Magnification of Dendrite containing: 1 = microtubules; 2 = mitochondria; 3 = rough endoplasmic reticulum. In the surrounding tissue are seen: 4 = numerous dendrites filled with vesicles. Arrows point to synaptic clefts.

Answer 46

A Dendritic process (1) extending from the cell body of a neuron. In the Perikaryon of the cell are stacks of rough endoplasmic reticulum (2) which represent the Nissl substance seen with the light microscrope. 3 = vesicle-filled process; 4 = vesicle-filled synaptic bouton. To the right, above and below, are two dark-ringed Myelinated Axons.

Answer 47

Cross-section of spinal cord nerve tract (white matter) consisting of many myelinated nerve processes (1). The nucleus of a Glial cell is also shown (2). Notice how different this picture of central nervous system is, as compared with a cross-cut of processess in a peripheral nerve (see next picture).

Answer 48

Myelinated nerve processes (1) from a peripheral nerve. 2 = Myelin Sheath; 3 = Nucleus of Schwann cell. Notice its Cytoplasm extending as the outermost layer of myelin.

Answer 49

Peripheral unmyelinated nerve fibers (1) cut in cross-section. Microtubules and Microfilaments are seen within the cytoplasm of the fibers. Surrounding each fiber closely is a thin strip of schwann cell cytoplasm. The Nucleus of a schwan cell is seen at (2).

Answer 50

Motor end-plate on skeletal muscle. NE = Nerve ending (The whole elongate profile lying next to the muscle cell); Psv = Presynaptic vesicles containing chemical transmitter. Notice that there are also electron-dense mitochondra in the cytoplasm of the nerve ending.
Labels related to the skeletal muscle are: Tt = T-Tubule of triad; Tcr = Cisternae of triad (seen in cross-section in the main photo and in long-section in the inset enlargement at upper left); Lsr = Long-section of sarcoplasmic reticulum; Jf = Junctional folds of sarcolemma inthe region of the motor ending (Myoneural Junction); M = Mitochondria in sarcoplasm surrounding myofibrils; Bl = Basal Lamina Outside of cell membrane of muscle cell. Notice it between nerve ending and muscle as well.

Answer 51

ARTERIOLE FROM THE KIDNEY OF A DOG.
1 - Lumen; 2 - Endothelial Cells; 3 - Internal Elastic Lamina; 4 - Smooth Muscle Cells

Answer 52

CROSS SECTION OF AN ARTERIOLE FROM THE KIDNEY OF A DOG.
1 - Lumen; 2 - Nucleus of endothelial cell; 3 - Internal elastic membrane; 4 - Nucleus of smooth muscle cell (notice the rather filamentous, “hairy” appearance of smooth muscle cytoplasm caught in many places around the whole wall of the-vessel); 5 - Portion of a fibroblast with vesicular-looking RER.

Answer 53

BLOOD CAPILLARY IN SKELETAL MUSCLE.
CL - Capillary lumen; RBC - Red blood cell; CE - Capillary endothelium (Note the many small, round, pale pinocytotic vesicles within the endothelial cytoplasm); M - Mitochondria; A - A band; I - I band; Z - Z line

Answer 54

High magnification of pericapillary space in the pineal of the rat. To the right is the capillary with its fenestrated endothelial lining cell (see membrane of fenestration at arrow). To the left of the micrograph are several processes of pinealocytes which-contain coated vesicles (1). The contents of the vesicles are supposedly secreted into the pericapillary space. Notice the thin gray line of basal lamina surrounding the processes and separating them from the pericapillary space. There are several mitochondria (2).

Answer 55

A pineal capillary demonstrating a thin endothelium with fenestrations (arrows). Some of the pinealocyte processes in the upper and lower corners of the photograph contain isolated dense-core (dark) vesicles(l).

Answer 56

Renal peritubular capillary with empty capillary lumen (cl). The dark-staining nucleus belongs to an endothelial cell. Notice that the thin rim of cytoplasm surrounding the nucleus continues on around the capillary lumen and shows the presence of many,fenestrations (f). Separate lines of basement membrane(bm), or more strictly basal lamina, can be seen underlying the capillary endothelium (ce) and the epithelial cells to the right and left and bottom of the picture.

Answer 57

Part of an endothelial cell lining of a capillary in the adrenal cortex. The cell has fenestrations bridged by thin membranes (arrows).
RBC - Red blood cell in capillary; M - Mitochondria in cortical secretory cell. Note the vesicular cristae typical of these cells.