Color Atlas A27
The wall of the trachea is made up of layers but these are quite different from other tissues described aboveMucosa is formed by pseudostratified ciliated columnar epithelium with goblet cells and the underlying lamina
propria
Submucosa is found deep to mucosa and is made up of loose connective tissue containing mucous and serous glands, blood vessels and ducts of the glands
The next layer is made up of hyaline cartilage. Chondrocytes increase in size from periphery to center. They may appear as isogenous groups surrounded by darkly stained territorial matrix.
External to the cartilage is the outer covering of collagen fibers called adventitia (not seen in slide).
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EYEBALL
The wall of the eyeball is made up of several layers as follows (from without inwards):
1.Sclera, made up of collagen fibers.
2.Choroid, containing blood vessels and pigment cells. The remaining layers are subdivisions of the retina.
3.Pigment cell layer.
4.Layer of rods and cones.
5.Outer nuclear layer.
6.Outer plexiform layer.
7.Inner nuclear layer.
8.Inner plexiform layer.
9.Layer of ganglion cells.
10.Layer of optic nerve fibers.
The appearance is not likely to be confused with any other tissue.
A28 Textbook of Human Histology
SOME ORGANS CONSISTING PREDOMINANTLY OF ACINI OR ALVEOLI
Acini are rounded structures found in glands. Each acinus appears as a rounded or oval mass. It is made up of cells but their boundaries are often not distinct. Each cell is more or less triangular, its base lying near the periphery of the acinus and its apex near the center of the acinus. Each acinus has a small lumen that is often not seen. Acini are of two types. Some of them are dark staining (and usually bluish) and are termed serous acini. Others are very light staining. These are mucous acini. In the mammary gland, the secretory unit is termed alveolus, not acinus. Please do not confuse the alveoli of mammary gland with the alveoli of lung!
MIXED SALIVARY GLAND (SUBMANDIBULAR GLAND)
The submandibular gland is characterized by the presence of both serous and mucous acini.
In some cases serous cells are present in relation to mucous acini forming demilunes.
Cut sections of ducts lined by cuboidal epithelium are seen.
Fig. A26.1: Submandibular gland (Low power)
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Fig. A26.2: Submandibular gland (High power)
Color Atlas A29
PANCREAS
This gland is made up of serous acini
The cells forming the acini of the pancreas are highly basophilic (bluish staining). The lumen of the acinus is seldom seen
Amongst the acini some ducts are present.Some acini may show pale staining “centro-
acinar cells”
At some places the acini are separated by areas where aggregations of cells is quite different from those of the acini. These aggregations form the pancreatic islets: these islets have an endocrine function.
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Fig. A27.1: Pancreas
MAMMARY GLAND
Fig. A28.1: Mammary gland
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Mammary gland consists of lobules of glandular tissue separated by considerable quantity of connective tissue and fat
Non lactating mammary glands contain more connective tissue and less glandular tissue
The glandular elements or alveoli are distinctly tubular. They are lined by cuboidal epithelium and have a large lumen so that they look like ducts. Some of them may be in form of solid cords of cells
Extensive branching of duct system is seen.
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A30 Textbook of Human Histology
SOME ORGANS SHOWING MULTIPLE TUBULAR ELEMENTS
KIDNEY
When we look at a section of the kidney we see that most of the area is filled with a very large number of tubules. These are of various shapes and have different types of epithelial lining. This fact by itself suggests that the tissue is the kidney.
The kidney is covered by a capsuleDeep to the capsule there is the cortexDeep to the cortex there is the medulla
of the kidney
In the cortex circular structures called renal corpuscles are present surrounding which there are tubules
The lumen of proximal convoluted tubules is small and indistinct. It is lined by cuboidal epithelium with brush border. The distal convoluted tubule has a simple cuboidal epithelium and presents a distinct lumen
The medulla shows cut sections of collecting ducts and loop of Henle. Collecting ducts are lined by simple cuboidal epithelium and loops of Henle are lined by simple squamous epithelium.
Cut sections of blood vessels are seen both in the cortex and medulla.
Fig. A29.1: Kidney
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Color Atlas A31
EPIDIDYMIS
The body of the epididymis is a long convoluted duct
It shows cut sections of tubules lined by pseudostratified columnar epithelium in which there are tall columnar cells and shorter basal cells that do not reach the lumen. The columnar cells bear stereocilia
Smooth muscles are present around each tubule
Clumps of spermatozoa are present in the lumen of the tubule.
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Fig. A30.1: Epididymis |
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SEMINAL VESICLE
The seminal vesicle shows highly convoluted tubule and irregular lumen
It has an outer covering of connective tissue, a thin layer of smooth muscle and an inner mucosa
The mucosal lining is thrown into numerous folds that branch and anastomose to form a network
The lining epithelium is usually simple columnar or pseudostratified.
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Fig. A31.1: Seminal vesicle |
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A32 Textbook of Human Histology
SOME ORGANS THAT ARE SEEN IN THE FORM OF ROUNDED
ELEMENTS THAT ARE NOT CLEARLY TUBULAR
TESTIS
The testis has an outer fibrous layer, the tunica albuginea deep to which are seen a number of seminiferous tubules cut in various directions
The tubules are separated by connective tissue, containing blood vessels and groups of interstitial cells
Each seminiferous tubule is lined by several layers of germinal cells which will eventually form the spermatozoa.
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Fig. A32.1: Testis
PROSTATE
The prostate consists of glandular tissue embedded in prominent fibromuscular tissue.
The glandular tissue is in the form of follicles with serrated edges. They are lined by columnar epithelium.
The lumen may contain amyloid bodies called corpora amylacea (pink stained).
The follicles are separated by broad bands of fibromuscular stroma.
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Fig. A33.1: Prostate
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Color Atlas A33
THYROID GLAND
The thyroid gland is made up of follicles lined by cuboidal epithelium
The follicles contain pink staining colloid. In the intervals between the follicles, there is some connective tissue
Parafollicular cells are present in relation to the follicles and also as groups in the connective tissue.
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Fig. A34.1: Thyroid gland
SOME TISSUES THAT APPEAR AS COLLECTIONS OF CELLS
LIVER
Many hexagonal areas called hepatic lobules are present. The lobules are partially separated by connective tissue
Each lobule has a small round space in the centre. This is the central vein
A number of broad irregular cords seem to pass from this vein to the periphery of the lobule
These cords are made up of polygonal liver cells (hepatocytes)
Along the periphery of the lobules there are angular intervals filled by connective tissue. Each such area contains a branch of the portal vein, a branch of the hepatic artery, and an interlobular bile duct. These three constitute a portal triad. The identification of hepatic lobules and of portal triads is enough to recognize liver tissue.
Fig. A35.1: Liver
A34 Textbook of Human Histology
SUPRARENAL GLAND
Fig. A36.1: Suprarenal gland
The suprarenal gland is made up a large number of cells arranged in layers.It consists of an outer cortex and an inner medulla.
The cortex is divisible into three zones.
The zona glomerulosa is most superficial. Here the cells are arranged in the form of inverted U-shaped structures or acinus-like groups
In the zona fasciculata the cells are arranged in straight columns (typically two cell thick). Sinusoids intervene between the columns. The cells of this zone appear pale
The zona reticularis is made up of cords of cells that branch and form a network.
The medulla is made up of groups of cells separated by wide sinusoids. Some sympathetic neurons are also present.
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Color Atlas A35
HYPOPHYSIS CEREBRI
The hypophysis cerebri consists of three main parts.
The pars anterior is cellular. It consists of groups or cords of cells with numerous sinusoids between themThe pars intermedia is variable in
structure
The pars posterior consists of fibers, and is lightly stained
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Fig. A37.1: Hypophysis cerebri
PARATHYROID GLANDS
These glands are made up of masses of cells with numerous capillaries in between
Most of the cells (of which only nuclei are seen) are the chief cells (small basophilic cells)
Oxyphilic cells and adipose cells are also seen. The number of oxyphilic cells is very less as compared to chief cells.
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Fig. A38.1: Parathyroid glands
A36 Textbook of Human Histology
CEREBRAL CORTEX
The cerebral cortex consists of many cells having varied shapes. Nerve fibers, myelinated and unmyelinated, are also present. Blood vessels are seen. The nerve fibers are arranged in several layers as follows (from without inwards).
Molecular layer consisting mostly of nerve fibers
External granular layer with densely packed nuclei
Pyramidal cell layer with large triangular cells
Internal granular layer
Ganglionic layer with large cells
Multiform layer with cells of varied shapes.
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Fig. A39.1: Cerebral cortex
SENSORY GANGLIA
Ganglia are of two types, sensory and autonomicIn sensory ganglion large pseudounipolar neurons
are arranged in groups that are separated by bundles of nerve fibers
Each neuron has a vesicular nucleus with a prominent nucleolus. The neuron is surrounded by a ring of satellite cells.
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Fig. A40.1: Sensory ganglia |
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