INTRODUCTION TO DYNAMIC HISTOLOGY (Laboratory Manual)
Plan of Basic Tissues (to be covered in the course)
I. Epithelial Tissue Covering epithelia
Simple -squamous (endothelium, mesothelium)
-cuboidal
-columnar
Stratified -squamous (keratinized, non keratinized)
-transitional
Pseudostratified
Glandular epithelia -exocrine
-endocrine
II. Connective Tissue Loose
Dense Irregular
Dense Regular -tendon
-ligament
Adipose
Cartilage -hyaline
-elastic
Bone -marrow
-blood
III. Muscle Tissue Striated (voluntary)
Smooth (involuntary)
Cardiac
IV. Nervous Tissue Central Nervous System -brain
-spinal cord
Peripheral Nervous System -nerves
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Slide Box
1. Skin - Finger
2. Striated Muscle - Diaphragm
3. Cardiac Muscle - Heart
4. Peripheral Nerve - Sciatic Nerve
5. Spinal Cord - Cross section
6. Cerebrum
7. Cerebellum
8. Tongue
9. Esophagus, Trachea, Elastic Arteries, Large Veins
10. Trachea, Esophagus
11. Lung
12. Lip - Skin with hair follicles
13. Submaxillary Salivary Gland
14. Pancreas
15. Liver
16. Pyloric Stomach, Duodenum
17. Small Intestine, Body of Stomach, Colon
18. Kidney
19. Mature and Developing Teeth
20. Sublingual Salivary Gland
21. Urinary Bladder
22. Bone formation
23. Lung and various other tissues
24. Compact Bone
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 1
Objectives
1. Use of the microscope.
2. Preliminary observation of skin (epidermis).
Assignments
1. Become familiar with the parts of the microscope and their use.
Identify the eye piece or ocular and objectives (and their magnifications), the
stage, the condenser. Condenser should be down with L.P. and up with H.P.
2. Become familiar with steps of observation.
Slide always facing up (touch coverslip for orientation).
Start with low power (L.P) end with high power (H.P.) and/or oil immersion.
Focusing. Coarse (with L.P.) and fine (with H.P.) adjustment.
What is a longitudinal, a cross and an oblique section?
3. Examination of slide 1. Identification of epidermis, dermis and hypodermis.
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 2
Objectives
1. To study the histology of the skin and its appendages (hair, sebaceous and sweat
glands).
2. To study the keratinized stratified squamous epithelium (epidermis).
3. To identify the phases of mitosis in the stratum germinativum (basal layer), i.e.,
interphase, prophase, metaphase, anaphase and telophase.
4. To identify the dermis and hypodermis.
Assignments
1. Use slide 1. Make a drawing of the epidermis at L.P and H.P.
2. Use slide 12. In the dermis, study the hair follicle and identify its layers (C.T.
sheath, glassy membrane, E.R.S., I.R.S., cuticle of hair shaft and cortex). Use
your Atlas of Histology and your drawings from the lecture. Note that the I.R.S. is
composed by the Henle’s layer, Huxley’s layer, and the cuticle of I.R.S.
3. Study the sebaceous gland at L.P. and H.P. Make a drawing.
4. Use slide 1. Study the sweat gland and its duct at L.P. and H.P.
5. Identify mitotic figures in the basal layer.
6. If you have time compare the epidermis to the dermis (C.T.) and hypodermis
(C.T.).
C.T.: connective tissue
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 3
Objectives
1. To study the classification and histology of the connective tissue (using the
dermis and hypodermis as study models).
2. Histology of cartilage
3. Introduction to the histology of the bone.
Assignments
1. Use slide 1. Study the dermis and hypodermis of the skin. The dermis is divided
into a papillary layer (loose connective tissue) and a reticular layer (dense
irregular connective tissue). The hypodermis is composed of adipose tissue (a
variety of loose connective tissue). Locate sweat glands and their ducts in these
layers of the skin.
2. Use slide 9. Locate the trachea. Examine the hyaline cartilage. Study the
perichondrium, the isogenous groups and the extracellular matrix. Identify
chondroblasts and chondrocytes.
3. Use slide 22 and locate dense regular C.T. (tendon). Note that the collagen fibers
run in one direction.
4. Slide 22. Note that the articular surface is made of hyaline cartilage. Do you see
pericondrium in this location?
5. Use slide 24. Bone. Cross section of shaft (long, compact lamellar bone). Identify
the following structures: periosteum, outer circunferential system or lamellae,
Haversian system, inner circumferential system or lamellae, endosteum, marrow,
osteoblasts, osteocytes, osteoclasts, Haversian canals (vascular canals).
6. Make drawings.
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 4
Objectives
1. To study the histology of the bone.
2. To study endochondral bone formation.
Assignments
1. Use slide 22. Review bone structure. Note the following points: Bone tissue is
made up of cells and matrix (matrix consists of collagen and ground substance).
The collagen is impregnated with minerals in the form of hydroxyapatite crystals.
2. Cells are: a- Osteoblasts (seen during bone formation) line the bone surfaces and
are large when active and flat when inactive. b- Osteocytes (lie in bone). They
are seen in small holes called lacunae. Osteocytes have processes which run in
small canaliculi in the bone matrix. c- Osteoclasts (bone resorption). These are
large multinucleated cells which remove bone (matrix, minerals and cells).
3. In the rat there are no true Haversian systems. But the canals containing blood
vessels may be considered to be Haversian canals. Review the following:
periosteum, endosteum, inner and outer circunferential systems and interstitial
system.
4. Study the articular surface (hyaline cartilage without pericondrium).
5. The bone that is first formed is embryonic or woven bone. This bone is laid down
around the cartilage model of the bone. The cartilage model is removed during
endochondral bone formation leaving two discs of cartilage at either end of the
bone; these are the epiphyseal plates. They are responsible for the growth in
length of the bones.
6. Study the epiphyseal plate. Identify the different layers (resting cartilage, zone of
proliferation, hypertrophy, cell death and mixed spicules.
6. Make drawings
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 5
Objectives
1. To study the histology of striated (skeletal) muscle.
2. To study the histology of cardiac muscle.
3. To study smooth muscle (wall of intestine).
Assignments
1. Use slides 2 and 8. Make drawings of longitudinal, cross and oblique sections of
muscle fibers (striated skeletal muscle). In cross sections identify peripheral
nuclei and myofibrils. In longitudinal sections note long multinucleated fibers,
peripheral nuclei and cross striations of the fiber.
2. Compare striated skeletal muscle to cardiac muscle (slide 3). Cardiac muscle is
similar to striated skeletal muscle, but has central nuclei and the fibers (cells)
are joined together at intercalated discs.
3. Compare striated skeletal muscle to smooth muscle (slide 17). Note fibers in
cross sections presenting centrally located nuclei. In longitudinal section the
fibers are elongated, spindle shaped with central nuclei.
4. Make drawings at L.P. and H.P.
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 6
Objectives
1. To study the histology of blood vessels (elastic arteries, muscular arteries,
arterioles, large veins, medium size veins and venules).
2. To identify the different layers of these vessels.
Assignments
1. Find a muscular artery (media with four or more layes of smooth muscle cells)
and a medium size vein in slides 1, 8, 9 and 12. In each case try to identify cross
and longitudinal sections. Examine the intima, media and adventitia. In the case
of the arteries find the internal elastic limiting membrane (IELM).
2. Identify other vessels such as arterioles and venules in the same sections. How do
they differ from muscular arteries and medium size veins?
3. Study elastic and large size veins. Use slide 9. Sketch a portion of the media of
the elastic artery showing fenestrated elastic membranes and the smooth muscle
fibers between them. What is and where is located the vasa vasorum?
4. Make drawings of all these vessels at L.P. and H.P.
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 7
Objectives
1. To study the histological organization of the trachea
2. To study the histology of the respiratory system
Assignments
1. Use slides 9 and 10. See that the lumen of the trachea is lined by a
pseudostratified columnar epithelium with cilia and goblet cells. Make a H.P.
drawing. The thin layer of connective tissue (loose) under the thickened
basement membrane is the lamina propria. This C.T. together with the epithelium
are collectively called mucosa. The connective tissue below the mucosa is the
submucosa and contains serous and mucous acini. Finally the submucosa merges
with an open ring of hyaline cartilage completely surrounded by perichondrium.
Look from chondrocytes (isogenic groups).
2. Find intrapulmonary bronchus. Study the folded mucosa, the incomplete plates of
cartilage and the presence of smooth muscle (Find slides in the wooden box).
3. Find bronchioles (regular, terminal and respiratory), alveolar ducts, alveolar sacs
and alveoli. Identify macrophages and pneumocytes type II.
4. Make detailed drawings of these structures.
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 8
Objectives
1. To study the histology of the digestive system
a) Teeth
b) Tongue
c) Esophagus
Assignments
1. Teeth. Slide 19 (Cross section of monkey maxilla). Find erupted primary tooth
and unerupted permanent teeth. Examine the gingiva and the periodontal
ligament around the erupted tooth.
2. Study the gingiva. Find, if possible, the muco-gingival junction. Identify the
parakeratinized squamous epithelium.
3. Study the erupted tooth. Find the dentine and odontoblasts, the pulp, the
cementum and cementocytes. Find the Sharpey's fibers in the cementum. The
enamel (crown) is absent (removed during decalcification). What is different
about the cementum near the crown and at the tip of the root?
4. Developing crowns of permanent tooth. Find the enamel (white space and/or
bluish material), the ameloblasts (inner dental epithelium), stratum intermedium,
stellate reticulum, outer dental epithelium and Hertwig's epithelial root sheath.
What is the enamel organ?
5. Make drawings of all these structures.
6. Tongue. Slide 8. Find filiform, fungiform and circumvallate papillas. In the last
one, find the taste buds. Make drawings.
7. Esophagus. Slides 9 and 10. The mucosa consists of a non-keratinized stratified
squamous epithelium and a thin lamina propia (loose C.T.). There is a muscularis
mucosa. The submucosa is thick (dense C.T.) and contains mucous glands. The
tunica muscularis has two layers. The outermost layer is called adventitia. Make
drawings.
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 9
Objectives
1. Study of the histology and general organization of the gastro-intestinal tract
(esophagus, stomach and intestines).
Assignments
1. Review esophagus.
2. Reed on your atlas about the cardiac portion of the stomach (no slides).
3. Body of the stomach. Slide 17. Find mucosa and identify pits and glands. The
lamina propria is squeezed between the gastric glands. The gastric glands extend
down to the muscularis mucosa. Note the thin submucosa and the tunica
muscularis composed of three layers of smooth muscle. Sketch these layers under
L.P. Identify the following cells: surface mucous cells, mucous neck cells,
parietal cells, zymogenic cells.
4. Pyloric portion of the stomach and duodenum. Slide 16. Follow the mucosa and
identify both regions. One follows the other. Note that in the pylorum, the glands
are lined by mucous cells. In the duodenum the mucosa forms villi and crypts.
The crypts are called crypts of Lieberkühn. In the epithelial lining (simple
columnar) identify enterocytes (columnar cells with brush border), goblet cells,
Paneth cells. Note the muscularis mucosa and beneath the submucosa containing
the Brünner's glands. Sketch these organs at L.P. and H.P.
5. Small intestine proper. Slide 17. Identify the submucosa and compare to the
submucosa of the duodeneum. Note that this portion corresponds to the jejunum.
Why? Make a drawing. Study the tunica muscularis. What is the serosa? Make
drawings.
6. Large intestine. Slide 17 (colon). The mucosa consists only of crypts of
Lieberkühn. There are no villi. Sketch the mucosa. Note the presence of many
goblet cells and few striated border cells.
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 10
Objectives
1. To study the histology of the glands associated with the digestive tract (salivary
glands, pancreas and liver).
Assignment
1. Salivary glands. Study the organization of compound glands in general. Note the
lobes subdivided into lobules. This subdivision is made by connective tissue as a
capsule with sub-partitions. Note the duct distribution as interlobar, interlobular,
and intralobular. Note that intralobular ducts are either intercalated or striated
ducts. a) Parotid Gland. Study in your Atlas the structure of the parotid gland
(section non available). All the acini are serous. Note that the intercalated ducts
are short and that the striated ducts are longer. b) Sublingual gland (slide 20).
Most acini are mucous, usually with serous demilunes. There are also a few
serous acini. Study the duct system. c) Submaxillary gland: (slide 13). Most
acini are serous, but there are some patches of mucous acini.
2. Pancreas (slide 14). a) Exocrine pancreas. Study the serous acini which make up
most of the pancreas. They are typical serous glands with the addition of
centroacinar cell nuclei in their centers. The duct system of the pancreas consists
of long intercalated ducts (low cuboidal epithelium) emptying into small
intralulobular ducts with cuboidal epithelium surrounded by a small amount of
C.T. These drain into larger interlobular ducts lined by a columnar epithelium
and surrounded by much C.T. Sketch these structures. b) Endocrine pancreas.
Constituted by small isolated islets of Langerhans surrounded by thin C.T. septa.
The cells within the islets are polyhedral and form cords around capillaries.
3. Liver (slide 15). Find the capsule of C.T. Identify the following structures: a) The
portal spaces containing a branch of the hepatic artery, portal vein and
interlobular bile duct. b) The central veins (center of the hepatic lobules). c) The
sinusoids and the cords of hepatocytes. Note that the sinusoids open into the
central vein. Identify the bile canaliculi between hepatocytes and the cholangioles
(small ducts linking the bile canaliculi with the interlobular ducts. Make sketches
of these structures.
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 11
Objectives
1. To study the histology of the kidney
2. To study the histology of the ureter and urinary bladder
Assignment
1. Kidney (Slide 18). L.P. observations: Find at the periphery of the kidney the
capsule and note the separation between the outer cortex and the inner medulla
(the cortex stains more intensely). In the cortex find branches of the interlobular
arteries which delimit the boundary of the lobules. The center of each lobule
usually has a straight medullary ray. H.P. observations: Find a renal corpuscle
and examine the parietal layer of Bowman's capsule, the glomerular tufts of
capillaries containing nuclei of endothelial cells, red blood cells, mesangial cells,
as well as the large light nuclei of podocytes (which correspond to the visceral
layer of Bowman's capsule). Draw a renal corpuscle uder H.P.
Find other renal corpuscles which show: a) the junction with the proximal
convoluted tubule; b) the point of contact with a macula densa of the distal
convoluted tubule; c) the point of junction of the glomerular tuft with afferent
and efferent arterioles. Sketch each of these images.
Study the proximal convoluted tubules (which are more numerous than the distal).
The cells are cuboidal and deeply acidophilics and contain round central nuclei.
The lumen is smaller than that of the distal convoluted tubules and is partly
occluded by material. The apical border of the cells has a brush border. Make an
H.P. drawing of a section of this tubule.
Study the distal convoluted tubule. The cells are paler and smaller than in
proximal tubules. There is no brush border and the lumen is wider. The nuclei of
the cells are close to the apical plasma membrane. Draw a section of this tubule.
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Study the medullary ray which is at the center of each lobule. The main duct in
the ray is the branched collecting tubule. The distal convoluted tubules drain into
it. The duct resembles the distal convoluted tubules, but the apices of the cells
seem to bulge into the lumen. The other tubules in the medullary ray are the
descending and ascending limbs of the loop of Henle. Identify the collecting
tubule, and make an sketch.
In the medulla identify the collecting tubules and the thin ad thick limbs of the
loop of Henle. Note the capillaries between the tubules; these can be confused
with the thin limbs of Henle's loop.
2. Histology of the ureter. It is a long muscular tube leading from the calyx of the
kidney to the urinary bladder. The lumen is star shaped in cross section and is
lined by transitional epithelium (Section 18 may or may not have a portion of this
organ). The lamina propria is elastic and merges with a submucosa, followed by
the muscle coat made up of 3 layers of smooth muscle (inner longitudinal, middle
circular and outer longitudinal). Find the beginning of the ureter at the hilus of
the kidney.
3. Histology of the urinary bladder (Slide 21). The bladder is a large muscular bag
for storing urine. It is lined by a transitional epithelium which is capable of great
distension. The smooth muscle coat is irregularly arranged in several layers.
Draw the transitional epithelium under H.P.
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ANATOMY AND CELL BIOLOGY
Introduction to Dynamic Histology
Laboratory 12
Objectives
1. To study the histology of the nervous system
Assignment
1. Spinal ganglion cell (no slides). Study in your atlas of histology of the spinal
ganglion and find the nerves emerging from it. The spinal ganglion consists of a
collection of the nerve cell bodies, nucleus plus perikaryon, of the neurons. These
are the largest cells in the ganglion. The perikaryon is surrounded by a layer of
cuboidal satellite cells which are type of neuroglia. Study the cell body of a
neuron. The nucleus is round, large, located in the center and contains a large
nucleolus. The cytoplasm contains large flecks of basophilic material, Nissl
substance, which is the ergatoplasm of the cell. The Nissl substance extends into
the larger dendrites, but not into the axon hillock and/or axon. Some neurons
contain dark yellow pigment granules called lipofuscin granules.
Peripheral nerve. Leaving the ganglion is the posterior root of the spinal nerve, a
peripheral nerve containing nerve fibers (myelinated axons) of the neurons of the
spinal ganglion. Define the epineurium, perineurium and endoneurium. Axons
are slightly basophilic. The myelin sheath appears acidophilic and vacuolated.
The larger nuclei, with pale chromatin are the nuclei of Schwann cells. The
thinner, darker nuclei are fibrocytes of the endoneurium. Observe node of
Ranvier.
2. Cross section of spinal cord (Slide 5). Note the C.T. (pia mater) around the cord.
Outside the pia mater are sections of peripheral nerves (the anterior and posterior
roots of the spinal nerves). Distinguish the gray and white matter. The gray
matter is in the form of an H. It contains the cell bodies of neurons. The white
matter is on the outside and contains the nerve fibers running in the cord. Both
gray and white matter contain nuclei of neuroglial cells. In the center of the cord
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is the central canal. It is lined by columnar cells, the ependymal cells. In the
anterior horn find the large neurons (anterior horn cells). Make drawings.
In the white matter there are nerve fibers, but the nuclei belong to three types of
neuroglia cells. The large pale nuclei are of astrocytes. The darker nuclei with a
distinctive nuclear membrane is the oligodendrocyte, and the smallest and darkest
nuclei, often irregular in shape are the microglia.
3. Study the section of the cerebellum (Slide 7). It is a sagittal section through the
horizontal convolutions called lobes. Each has numerous secondary foldings,
each being a folium. Study one cerebellar lobe; note the folia; find the core of the
white matter in the center of the lobe. Study the gray matter of the cortex. It
consists of three distinct layers. Next to the white matter is the granular layer,
containing numerous nuclei of small neurons. In the middle there is a single layer
of large cells with large dendritic processes extending into the outermost layer
called Purkinge cells. The outermost layer is the molecular layer and it is
composed of numerous neuronal processes and glial cell nuclei.
4. The cerebrum (Slide 6) shows some convolutions or folds. Identify again the
centrally located white matter and the gray matter on the outside. The cerebral
cortex of gray matter consists of poorly defined layers. An inner layer next to the
white matter, the polymorphic cell layer, consists of neurons of irregular and
variable size. In the middle pyramidal cell layer, the neurons tend to be shaped
like pyramids of differing size (some of these neurons have very large cell
bodies). The outermost layer is the molecular layer consisting of neuronal
processes and glial cells. Note that glial cells are also present in the outer cortical
layers. Also note that the vascular thin layer of C.T. on the outer surface of the
cerebrum is the pia mater and it is the innermost protective membrane for the
brain.
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