Epithelial Tissues
Neuron (Nerve Cell) - I
The pictures to the left are light micrographs of neurons (nerve cells). The light micrographs
show the typical appearance of neurons when stained with basic dyes. The nucleus is pale;
often a heavily stained nucleolus is evident within it. Nissl bodies are prominent in the
cytoplasm near the nucleus.
These three are scanning electron micrographs. They
show a three dimensional view of a neuron (nerve cell).
The main part or body of the neuron is pear shaped. It
contains the nucleus and most of the organelles and
structures in the cell. The long thin “arms” or
processes of the nerve cells connect to other nerve
cells. Signals from one nerve cell to the other travel
along these processes.
Neuron (Nerve Cell) - II
The electron micrograph shows
part of the cell of a neuron. Part
of the nucleus is at center-left.
Stacks of rough endoplasmic
reticulum are evident in the
cytoplasm. They are what are
called the Nissl bodies at the light
microscopic level.
This neuron was labeled with a
marker. The location of that
marker is represented by the
black granules, many of which
localize in the vicinity of the Golgi
apparatus. The black marker is
taken up at one end of the cell
by one of the arms and
transported by the cytoskeleton
back towards the nucleus.
Neurons “talk” to other neurons using chemical
messages. The chemical messages are
special molecules that the neuron makes and
stores in very small vacuoles close to the cell
membrane at the ends of its processes. When
the neuron wants to talk to the next neuron, the
tiny vesicles inside the cell move to and fuse
with the neuron’s cell membrane, dumping the
special chemicals outside of itself. The next
neuron gets the chemical signal because
special protein molecules in its cell membrane
capture the special chemicals and move them
inside.
Bone Cell - I
Scanning electron micrograph
(colour enhanced) of a bonedegrading osteoclast
Bone is a living tissue that is
constantly being broken down and
rebuilt. This image shows an
osteoclast, a type of cell
responsible for degrading bone. The
space surrounding the cell is known
as a resorption cavity.
Young bone cells
(osteoblasts produce the
intercellular bone matrix,
an organic material
consisting of collagen
fibers and ground
substance. This matrix
gradually calcifies and
hardens
Bone Cell - II
This photograph of a normal bone
was taken through the microscope.
Bone is green. The white dots are
fat cells in the bone marrow and
the other bone marrow cells are
dark red.
Goblet Cells – Intestines I
Goblet cells secrete mucus, a viscous fluid composed primarily of proteins called mucins.
Mucus serves many functions, including protection against stress and chemical damage, and,
especially in the respiratory tree, trapping and elimination of particulate matter and
microorganisms.
Goblet cells are found scattered among other cells in the epithelium of many organs,
especially in the intestinal and respiratory tracts. In some areas, their numbers are
rather small relative to other cell types, while in tissues such as the colon, they are much
more abundant.
Secretion of mucus occurs by exocytosis of secretory granules
The mucus in goblet cell granules
is condensed, but upon secretion,
expands in volume tremendously
and almost instantaneously (picture
a pressurized can of shaving foam or
whipped cream). In some systems
studied, the mucin gel increases in
volume 500-fold during a period of
only 20 milliseconds!
Increased numbers of goblet cells are
observed in several disease states. Chronic
brochitis and cystic fibrosis are examples of
diseases in which goblet cell hyperplasia or
metaplasia occurs.
Goblet Cells – Intestines II
Skin Cell
pinosum is composed of several layers of polyhedral cells, which flatten as the stratum granulosum is approached. Se
ch are specific for keratin pairs 1 and 10. Individual cells appear to be separated by spaces that are traversed by t
be seen as fine lines between adjacent cells. They account for the prickly appearance of the cells and for their fre
tifacts caused when water is removed during the dehydration step. Spinous cells are attached to their neighbors by
main as the fragile
Skeletal Muscle I
Cardiac Muscle I
A special type of muscle found
only in the heart. It shares the
characteristics of both other
types of muscle found in the
human body.
Each cell has only one centrally located nucleus. Note the faintly
stained transverse bands called intercalated disks (indicated by the
blue arrows) that mark the boundaries between the ends of the
cells. These specialized junctional zones are unique to cardiac
muscle.
Cardiac Muscle II
In this electron micrograph, a
part of the nucleus appears as an
thin oval body in the lower right
side of the picture. Around it is a
small area of cytoplasm. The bulk
of the cardiac muscle cytoplasm
is occupied by the actin and
myosin protein fibers that are
responsible for muscle movement.
Right next to each group of
fibers is a mitochondron.
Skeletal Muscle II
Sperm Cell
Mid-piece region of a
mammal sperm
showing the
numerous
mitochondria that
provide the energy
for motility. ,
Egg Cell I
EM of an oocyte with its nucleus (5) at the bottom of the
micrograph. The nuclear envelope is sectioned tangentially so
that nuclear pores are clearly visible (arrows). 1 = Crystalline
bodies or plaques (typical of oocyte cytoplasm); 2 =
Mitochondria; 3 = Multi vesicular body; 4 = Cortical granules
(typical of oocyte); 5 = Nucleus.
Egg Cell II
Pancreatic Cell
Islets of
Langerhans Cell
Normal islet stained for
insulin (right) and
glucagon (left):
Tissue sections from a 24-h duct-ligated rat pancreas. a:
Semi-thin section illustrating an islet of Langerhans
(IL) in which some cells located either at the periphery
or in the core of the islet display some zymogen-like
granules (arrows). Ac, Acinar cells.
Magnification = ×2,800. b: Electron micrograph of an
insulin-secreting cell (Ins) surrounded by 2 acinar cells.
Islet cell displays some zymogen-like granules (arrows).
Delineation of each cell is particularly conspicuous by
differences in electron density of the cytoplasm. DL,
duct lumen. Magnification = ×10,000.
Tendon – Connective
Tissue
Tendon, which is a strap like body
that connects bone to muscle, is made
of dense, regular connective
tissue. You can find an example in
slide 9. The fibers are oriented in
parallel arrays. Note the thin, dark
staining nuclei of the
fibroblasts. Their cytoplasm cannot
be distinguished. How does the
arrangement of the fibers help a
runner sprint or a k
ngaroo jump?
Fat Cell
Here you see ADIPOSE cells (adipocytes), exhibiting
their characteristic "chicken-wire" look. The large
empty spaces represent the cytoplasmic areas
originally filled with lipid, extracted during slide
preparation. Only a very attenuated rim of cytoplasm
is present with the nuclei squeezed between the lipid
and the internal face of the plasma membrane. The
arrows indicate some of the adipocyte nuclei. Some
capillaries are also visible; adipose tissue is wellvascularized.
White Blood Cells - I
White blood cells (colourenhanced scanning electron
micrograph)
The cells of the immune system
(these white blood cells) play
key roles in the inflammatory
response. In this image we can
see three white blood cells - a
macrophage (brown) and two Tlymphocytes (blue).
White Blood Cells
PLASMA CELLS are seen here as the largest
cells with a dark, "cart-wheel" heterochromatin
pattern in the eccentric nucleus, with highly
basophilic cytoplasm. (a) indicates a large
lymphocyte, as defined by the lack of an
extensive cytoplasmic skirt. The smaller cells
are lymphocytes and some plasma cells.
Lymphocytes will have a dark, "smudged"
nucleus and very little cytoplasm in relation to
nuclear volume.
An EM of a plasma cell, indicating that the
extreme basophilia seen in the preceding slide
is caused by an abundance of rough
endoplasmic reticulum producing antibody
molecules for export.
Liver Cell