Dr. Mhawi 4 Overview of the Epithelium Flashcards
(118 cards)
1
Q
True or False: epithelium is avascular
A
True
2
Q
Explain the general characteristics of epithelium
8.5.7
A
8.5.7
3
Q
Explain this image
A
EPITHELIOIDS:
–lack a free surface
Epithelioid organization typically found in endocrine glands:
–islets of Langerhans in the pancreas
–interstitial cells of LEYDIG in testis
–luteal cells of ovary
–adrenal gland
–many epithelium-derived tumors
4
Q
What are the 6 functions of epithelium and give an example?
A
Secretion
- Epithelium lining trachea and bronchial tree secretes mucus
- Epithelium lining Stomach secretes mucus and gastric juice
Absorption:
- As in the epithelium of the intestine and the proximal convoluted tubules of the kidney
Transport:
- As in transport of materials along the surface of epithelium by motile cilia
Protection:
- Water barrier of the stratified squamous epithelium of the skin
- melanocyte protect against UV light
Sensation:
–Epithelial cells involved in sensation are called neuroepithelial cells
Sensation:
–Epithelial cells involved in sensation are called neuroepithelial cells
nBarrier:
–Epithelial cells lining the intestine and/or blood vessels are joined to each other by tight junctions (AKA Occluding junctions)
5
Q
________ is one cell-thick layer of flat cells
A
SIMPLE SQUAMOUS
–lines blood and lymphatic vessels
–wall of Bowman’s capsule in kidney
–lines the walls and covers the content of the abdominal and thoracic cavities
–lines respiratory alveoli of the lung
6
Q
Explain this image
8.5.7
A
Section of a vein. All blood vessels are lined with a simple squamous epithelium called endothelium (arrowheads). Smooth muscle cells in the vein wall are indicated by arrows. Pararosaniline-toluidine blue (PT) stain
8.5.7
7
Q
Explain this image
8.5.7
A
Simple squamous epithelium (arrows) in the wall of the Bowman’s capsule of the kidney.
8.5.7
8
Q
Special Terminologies for the Simple Squamous
_______ –name given to simple squamous epithelia lining blood and lymph vessels and the ventricles and atria of the heart
_______ name for simple squamous epithelia that line walls and cover contents of closed cavities of body:
- Abdominal cavity
- thoracic cavity
A
Endothelium
Mesothelium
8.5.7
9
Q
Explain this image
8.5.7
A
Endothelium
- 5.7
- 5.7
10
Q
Explain this image
8.5.7
A
A, light micrograph of the mesothelial cells covering the lung (pleura). B, Cells of the simple squamous epithelium in general appears as tiles with centrally located nuclei when viewed tangentially (from the top).
8.5.7
11
Q
Explain this image
A
Light micrograph of the mesothelial cell covering the mesentery (connective tissue covering the intestine).
12
Q
What ate the two exceptions to sqamous classification
A
–post capillary venules of the lymph nodes
- AKA high endothelial venules
- endothelial cells are cuboidal (arrowheads)
–venous sinuses of spleen
§endothelial cells are rod-shaped
–Called stave cells
13
Q
____ are one cell-thick layer of cubic (cuboidal) cells
A
SIMPLE CUBOIDAL
–found in:
§wall of thyroid follicles
§walls of kidney tubules
§surface of ovary (germinal layer)
8.5.7
14
Q
Explain this image
A
Walls of thyroid gland is made of simple cuboidal epithelium. Arrows point to capillaries.
8.5.7
15
Q
Explain this image
A
Simple cuboidal epithelium from kidney collecting ducts (upper part of the ducts).
16
Q
______ are one cell-thick layer of tall cells
A
SIMPLE COLUMNAR
–lines:
§intestinal tract from stomach to rectum
§uterus and cervix
§kidney collecting ducts
8.5.7
17
Q
Explain this image
A
Small intestine lumen is lined by simple columnar epithelium. Goblet cells specialized in secreting mucus (stained magenta) are also visible.
8.5.7
18
Q
Explain this image
A
Simple columnar epithelium covers the inner cavity of the uterus. Note that the epithelium (E) is separated from the underlying loose connective tissue of the lamina propria (LP) by a basal lamina (BL). The epithelium, basal lamina and lamina propria constitute the mucosa. H&E stain.
8.5.7
19
Q
Explain this image
8.5.7
A
Simple columnar epithelium from the kidney collecting ducts (lower parts of the ducts).
8.5.7
20
Q
Explain this image
A
Fundic stomach lined by simple columnar epithelium. PAS stain.
21
Q
_____ are two-cell or more epithelium
A
Stratified
Types
–Stratified squamous
§Keratinized and non-keratinized
–Stratified cuboidal
–Stratified columnar
–Transitional
22
Q
____ superficial layer is squamous that functions as a barrier
A
STRATIFIED SQUAMOUS
nLocation:
–Epidermis
–lining of oral cavity
–lips
–lining of esophagus
–lining of vagina
23
Q
Explain this image
A
24
Q
Expalin this image
8.5.7
A
Esophagus, stratified squamous nonkeratinized. Arrow points to a longitudinal section of blood vessel. Remember, epithelial tissue is avascularized tissue. Nutrients diffuse from the underlying blood vessels.
8.5.7
25
Explain this image
Lip, stratified squamous epithelium. Lightly keratinized. Iron hematoxylin.
26
Explain this image and how can you tell it is different than the esophagus photo?
Vaginal epithelium. Stratified squamous nonkeratinized.
8.5.7
27
\_\_\_\_ are located in:
## Footnote
–ducts of sweat gland
–larger ducts of exocrine glands (mammary gland, as an example)
–anal canal (most distal portion of the GIT)
STRATIFIED CUBOIDAL
Function as
–barrier
conduit
28
Explain these images
Left: Section of the sweat gland showing both the secretory and ductal portions. The duct is cut longitudinally. Note that the secretory portion gives multiple sections because it is tortuous structure. Right: High magnification of the duct and secretory portions. Both parts are cut transversely. Duct (solid arrows) of sweat gland lined by stratified cuboidal epithelium. The stratification (represented by two rows of nuclei) is visible in the oblique section of the duct that is labeled with the star. The duct appears darker than the secretory portion of the gland (dashed arrows). Multiple transverse sections that belong to the duct and secretory portion of the same gland appear in this micrograph due to the coiling of the duct and the secretory portion on its self.
29
\_\_\_\_ are:
Located in:
–largest ducts of exocrine glands
–anal canal
8.5.7
STRATIFIED COLUMNAR
30
Explain this image
Wall of the excretory duct of the salivary gland is comprised of stratified columnar epithelium.
31
\_\_\_\_\_ are
–AKA urothelium
–stratified
–functionally accommodates distension
–serves as a barrier
–located in: renal calyces, ureters, urinary bladder, proximal part of the urethra
nTRANSITIONAL
32
Explain this image
## Footnote
8.5.7
Transitional epithelium lining the ureter.
8.5.7
33
Explain this image
Transitional epithelium, urinary bladder
8.5.7
34
Explain this image
Transitional epithelium (green double-headed arrow) of the urinary bladder. Note vascularization (red arrow) in the loose connective tissue under the epithelium
Dome shape
35
\_\_\_\_\_\_
## Footnote
–has appearance of being stratified
–some cells do not reach the free surface
–nuclei appear arranged in more than one row
–ALL cells rest on the basal lamina
–it is actually a simple epithelium
Pseduostratifie
- limited distribution in body:
upper respiratory tract (trachea, bronchi)
epididymis (male reproductive system
ductus deferens (male reproductive system
8.5.7
36
Explain this image
Pseudostratified columnar ciliated.
37
Explain this image
Pseudostratified columnar ciliated. Green arrows point to mucus-secreting (goblet) cells. Black arrows indicate the cilia.
38
Explain this image
Pseudostratified columnar epithelium lining the duct of the epididymis of the male reproductive system. The lumen of the epididymis contains sperms. The appendages projecting from the free cell surface into the lumen are not to be confused with cilia. They are stereocilia (extra long microvilli).
8.5.7
39
\_\_\_\_\_ is
## Footnote
–acellular structure
–structural attachment site
Attaches the overlying epithelial cells to the underlying connective tissue
–its components are synthesized and secreted by epithelial cells
Components assembled extracellularly at the base of the epithelial cell
8.5.7
Basal Lamina (basement membrane)
**_§Periodic Acid-Schiff stain (PAS)_**
**_§silver salts_**
40
Explain this image
## Footnote
8.5.7
PAS stain reveling basal laminae (pl. of lamina) in the Kidney.
8.5.7
41
Explain this image
## Footnote
8.5.7
Upper right inset is a low magnification micrograph of the colon. The intestinal glands appear as elongated tubes lined with epithelial cells among which mucus-secreting (goblet) cells are visible. The glands appear round (images a and b) if they are cut transversely (dashed white line in the inset). Image (a) represents H&E preparation. In this micrograph basal lamina is not stained and the cytoplasm of the mucus-secreting cells appear empty. If the tissue is stained with PAS (image b) both basal lamina (arrows) and mucus are clearly visible and exhibit magenta color.
42
nAfter conventional _TEM_ observation basal lamina reveals two layers:
LAMINA DENSA
- Electron dense layer
- Contains network of fine filaments
LAMINA LUCIDA (lamina rara)
- clear space between base of cell and lamina densa
- believed to be an artifact caused by the shrinkage of the epithelial cells during the tissue preparation
43
Explain this image
Basal portions of two cells and parts of their nuclei. The cells are resting on a basal lamina (BL) below which collagen (reticular) fibrils are visible . Note the interdigitations between the two cells at the lateral sides.
8.5.7
44
Explain this image
## Footnote
8.5.7
a) Electron micrograph of a basal lamina and its associated protein, anchoring fibrils (filaments) (black arrows) which appear to loop around or attached to the thicker, cross-sectioned, reticular fibrils (red arrows). b) simplified illustration of the TEM.
45
nIn most of the epithelia basal lamina associates with underlying \_\_\_\_\_\_
–reticular fibers are type III collagen
Basal lamina attaches to underlying reticular fibers by \_\_\_\_\_\_
–Anchoring fibrils are Type VII collagen
RETICULAR FIBERS
ANCHORING FIBRILS (FILAMENTS)
46
Explain this image
## Footnote
8.5.7
Upper panel: BM, basal lamina found in the kidney glomerulus (group of blood capillaries inside the renal corpuscle). The thick basal lamina is a joint product of the endothelial cells lining the blood capillaries and another type of epithelial cells called podocyte cells which cover the blood capillaries from the outside. Lower panel: The basal lamina (BM) in the lung alveoli is lodged between the endothelial cells lining the blood capillaries and the epithelial cells lining the alveoli. Note that in the kidney glomerulus and lung alveoli the basal lamina does not associate with reticular fibers. RBC, red blood cell.
47
What are the 5 functions of the basal lamina
Tissue Scaffolding
–basal lamina serves as a guide or scaffold
allows rapid epithelial repair and regeneration
Peripheral nerve regeneration proceeds on a new basal lamina that is laid down by regenerating Schwann cells
Filtration
–movement of blood filtrate in the kidney
–through negatively charged molecules in lamina rara and network of collagen fibrils in lamina densa
–i.e. filtration is regulated by ION EXCHANGE and MOLECULAR SIEVE
structural attachment
–epithelial cells to connective tissue
compartmentalization
–separates connective tissue from epithelia, nerve tissue, and muscle tissue
48
\_\_\_\_\_\_ is peripheral extracellular electron-dense material
## Footnote
–visible in TEM
–appears the same as basal lamina
External Lamina
–positive staining with PAS and sliver
–found on external surface of non-epithelial cells:
§muscle cells
§nerve-supporting cells (Schwann cells)
§adipocytes (fat-storing cells)
49
Explain this image
TEM of myelinated axon (left) and striated muscle (right). Both cell types are surrounded by external lamina (red arrows). Stars in the left micrograph indicate the myelin sheath.
8.5.7
50
\_\_\_\_\_\_\_\_ is:
–Nonmembranous cytoplasmic filamentous organelles
§Actin filaments
§Intermediate filament
§Microtubules
Cytoskeleton
## Footnote
–Involved in
§movement of the cytoplasmic organelles
§Movement of cilia
§Contraction of the cell
§Adhesion of cell to cell and cell to extracellular matrix
51
\_\_\_\_\_\_\_
–cytoplasmic processes extending from cell surface
\_\_\_\_\_\_
–microvilli of unusual length
\_\_\_\_\_\_\_
–motile and non-motile cytoplasmic processes
\_\_\_\_\_\_\_\_
–invaginations and evaginations of cell surface
–create interdigitating and interleaving tongue and groove margins
for apposed cells
MICROVILLI
STEREOCILIA
CILIA
LATERAL and BASAL CELL SURFACE FOLDS and PROCESSES
8.5.7
52
\_\_\_\_ are distinctive cytoplasmic extensions at apical surface seen with LM in fluid transporting cells of gut and kidney
## Footnote
–provide enormous increase in free surface area
MICROVILLI
In the small intestine called: _striated border_
In the kidney tubules called: _brush border_
53
Explain this image
ncontain conspicuous core of **ACTIN** microfilaments
- actin microfilaments are anchored to plasma membrane at tip and sides
- extend down where they interact with horizontal network of actin filaments, the **TERMINAL WEB**
- filaments of terminal web are **contractile**
- this could result in decreasing diameter of apex of intestinal absorptive cell
- thereby the microvilli spread apart and the intermicrovillus space increases
- leads to an increment in the effective absorptive surface between microvilli
54
Explain this image
Electron micrograph of the apical region of an intestinal epithelial cell. Note the terminal web composed of a horizontal network that contains mainly actin microfilaments. The vertical microfilaments that constitute the core of the microvilli are clearly seen. An extracellular cell coat (glycocalyx) is bound to the plasmalemma of the microvilli.
55
Explain this image
## Footnote
8.5.7
Electron micrograph of a section from the apical region of a cell from the intestinal lining showing cross-sectioned microvilli. In their interiors, note the microfilaments in a cross section. The surrounding unit membrane can be clearly discerned and is covered by a layer of glycocalyx, or cell coat. x100,000.
8.5.7
56
\_\_\_\_\_\_\_ are
- extremely long immotile processes extending
from apical cell surface
- like microvilli, they are supported by actin filaments
STEREOCILIA
## Footnote
Found in:
–Epididymis
–facilitate absorption of fluid
-aggregate into pointed bundles
(like wet paintbrush)
8.5.7
57
True or False : Stereocilia also found in sensory hair cells of the inner ear
8.5.7
True
## Footnote
8.5.7
58
\_\_\_\_\_ are
Hair-like extension of the apical plasma membrane
nContain axoneme
–microtubule-based core
–extends form the basal body
§Basal body is a microtubule organizing center (MTOC
Cilia
Three classes of cilia
–Motile (active movement)
–Primary (passive movement)
–Nodal (active movement)
59
Explain this image
## Footnote
8.5.7
Left: LM micrograph of the pseudostratified epithelium of the respiratory system. The apical domain of the cell exhibit cilia (arrows). Right: the rectangle-bound area is magnified at the ultrastructural level. The core of the cilia is occupied by microtubules that arise from the basal bodies.
8.5.7
60
\_\_\_\_\_\_\_ may be several hundred cilia per cell, play cleansing role in respiratory tract, sweep mucous and trapped particulate material toward oropharynx, in oviduct cilia help sweep ova and fluid toward uterus
Motile cilia
61
Explain this image
TEM reveals internal core of microtubules
–Axoneme (fig. a)
–Microtubules are made of tubulin subunit
In cross sectional view
–9 doublets or pairs of circularly arranged peripheral microtubules surrounding 2 central microtubules ( 9+2; fig. b)
–Peripheral microtubules are designated A and B (fig. c)
–Share portion of the wall
62
How does the movement of cila work
nciliary activity based on movement of doublet tubules
–in relation to one another
neach doublet exhibits a pair of arms that contain **DYNEIN** (microtubule-associated protein) and **ATPase**
nthe arms extend from the A microtubule to form temporary **cross-bridges**
–with the B microtubules of the adjacent doublet
nhydrolysis of ATP produces a sliding movement of the bridge along the B microtubule
- as a result the cilium bends
nelastic connection provided by **nexin** protein brings the cilium back to straight position
63
Explain the image
a, cross section of a cilium showing the arrangement of the microtubules as 9 peripheral doublets and 2 central microtubules. In each doublet, the microtubule-associated motor proteins, dynein (red arrows), appear as two arms extending from microtubule A in one doublet toward microtubule B of the adjacent doublets. b, The cross section of this cilium shows the absence of dynein motor proteins, a condition resulted in **_primary ciliary dyskinesia._**
64
explain the image
Panel A: TEM image of negative-stained 2019-nCoV particles. Panel B: Ultrathin TEM section showing 2019-nCoV particles in the human airway epithelial cell. Arrowheads indicate extracellular virus particles, arrows indicate inclusion bodies formed by virus components, and triangles indicate cilia. Note the damaging effect of the virus to normal organization of the cilia.
65
\_\_\_\_\_\_ are
## Footnote
Axoneme is 9+0 microtubules
i.e., no central doublet microtubules
–None motile
§Passively bend by the flow of fluid
or sound
–only single cilium per cell is present
Called kinocilium
Primary cilia
–found in the epithelium of rete testes, hair cells of the inner ear, bile ducts, kidney collecting ducts, retina
–considered as important signaling devices
66
\_\_\_\_\_\_
–Found on the bilaminar embryonic disc
-Concentrated in the area that surrounds the primitive nodes
Nodal cilia
–Important role in early embryonic development
- Generating the left-right asymmetry of internal organs
67
Explain this image
Lateral folds between intestinal epithelial cells. The cells are not transporting fluid at this time since the folds are interlocked with each other and the intercellular space is not visible. The folds disappear and the intercellular space becomes wide and visible once these cells become active in fluid transport. Not goblet cell at the upper right corner.
68
Explain this image
Well developed in fluid-absorptive cells; e.g., kidney tubules
Help with the distention of the intercellular space (ICS)
Water transported from the lumen of the tubules to cell cytoplasm by water channel protein (aquaporin-1)
Na+ ions is actively pumped into the ICS by Na+/K+ pump
–Energy is provided by the abundant mitochondria
Cl- ions follow Na+ ions
Increased concentration of Na+ and Cl- ions in the ICS is the driving force that moves water from the cell cytoplasm into ICS
–Facilitated by the presence of aquaporin-1 in the lateral plasma membrane
Hydrostatic pressure builds up in ICS
Water is prevented from returning back to the lumen of the tubule due to the presence of tight junction between the cells
Water is forced to move through the basement membrane to blood capillaries located in the underlying connective tissue
8.5.7
69
Explain this image
Lateral enfolding of apposed plasma membranes. Left: cells are not active. The intercellular space is narrow and the lateral folding are visible. Right: Cells are actively absorbing fluid. The intercellular space is wide and the lateral enfolding disappeared.
8.5.7
70
\_\_\_\_\_\_\_ are characteristic of fluid-transporting cells
–prominent in
§proximal and distal tubules of kidney
§salivary gland ducts
8.5.7
Basal folds
## Footnote
8.5.7
71
Explain this image
## Footnote
8.5.7
a, light micrograph of a cross section of striated duct. b, TEM image of the rectangle area in (a). The electron micrograph reveals the folds of the basal plasma membrane of cells in the wall of the duct. Note the presence of the mitochondria (asterisks) within the folds.
72
Explain this image
## Footnote
8.5.7
Cells in the wall of the proximal convoluted tubule. Note the basal folds and the mitochondria in the vicinity of the folds.
73
Epithelial cells are tightly adherent to each other and to the underlying extracellular matrix through\_\_\_\_\_\_
junctions
## Footnote
Serve as:
–Sites attachment
–Barrier to diffusion of molecules between the epithelial cells
74
Explain this image
Junctional complexes (arrows) at low magnification TEM.
75
\_\_\_\_\_\_
§AKA occluding or tight junction
§Forms a ring or circumferential band (hence the name zonula) around the cell
§Serves as diffusion barrier
–seal created by transmembrane proteins **_(occludins and claudins)_**
ZONULA OCCLUDENS
## Footnote
8.5.7
76
\_\_\_\_\_\_\_
§continuous band-like adhesion
§surrounds cell and joins it to neighbors
–formed by the binding of transmembrane proteins _E-cadherin_ of neighboring cells (lateral adhesion
\_\_\_\_\_\_
§localized spot adhesion
§located at multiple sites on lateral surfaces of adjoining cells
8.5.7
–ZONULA ADHERENS
–MACULA ADHERENS, or DESMOSOME
8.5.7
77
Explain this image
## Footnote
8.5.7
Electron micrograph of a section of epithelial cells in the large intestine showing a junctional complex with its zonula occludens (ZO), zonula adherens (ZA), and desmosome (D). Also shown is a microvillus (MV). x80,000.
8.5.7
78
Explain this image
## Footnote
8.5.7
a) Free fracture preparation of zonula occludens. This TEM image reveals an anastomosing network of ridges (arrows) located on the fractured membrane near the apical part of the cell. The ridges represents linear arrays of transmembrane proteins occludins and claudins responsible for the formation of the zona occludens. Note the presence of microvilli at the apical part of the cell. b) Diagram showing the organization and pattern of distribution of the transmembrane protein occludin and claudins within the occludin junction.
8. 5.7
79
Explain the image
## Footnote
8.5.7
Left panel: Cardiac muscle fibers revealing intercalated disc (one of of which is examined at the TEM level (right panel). In the TEM, the intercalated disc appears to contain fascia adherens. Fascia adherens strongly adheres the cardiac muscle fibers.
80
\_\_\_\_\_\_\_\_ are
–small adhesion spots on the lateral domain of the cell
–strong attachment structure
–In simple cuboidal or simple columnar epithelium desmosomes are found in conjunction with occluding and adhering junctions (slides 95, 99, 103)
MACULA ADHERENS (DESMOSOMES)
81
Explain this image
Upper panel: TEM of macula adherens (desmosome). The arrows shows the intermediate filaments that bind to the attachment plaque. The attachment plaque is formed by desmoplakins and plakoglobins. The intercellular space is occupied by electron-dense material (arrowheads) formed by the interdigitation of the transmembrane proteins, desmocollins and desmogleins.
Lower panel: schematic diagram showing the structure of the desmosome. Note the interdigitation of the transmembrane proteins.
82
\_\_\_\_\_\_ are found between
## Footnote
§Epithelial cells
§Smooth muscle cells
§Cardiac muscle cells
§neurons
GAP JUNCTIONS, or NEXUSES
needed where activity of adjacent cells must be coordinated:
–heart muscle
83
\_\_\_\_\_\_\_ –each connexon comprised of six connexin proteins
TRANSMEMBRANE CHANNELS
84
Explain the images
Right column: Top; simplified illustration showing the accumulation of the transmembrane channels (connexons; green) into gap junctional plaque. Each connexon comprised of 6 proteins called connexins. Connexins arranged themselves into hydrophilic channels that allow the movements of ions and small regulatory molecules between the adjacent cells. Middle; replica of freeze-fractured membrane revealing gap junctional plaque. Bottom; gap junctional plaque imaged by atomic force microscope. Lower right: TEM image of thin plastic section showing a gap junction (between the red arrows) between two cells.
85
\_\_\_\_\_\_\_ are
## Footnote
–half-desmosome located on basal surface of the cell
–found in epithelia subject to abrasion and mechanical shearing
HEMIDESMOSOMES
## Footnote
§cornea
§skin
§mucosae of:
–oral cavity
–Esophagus
–vagina
86
Explain the images
TEM exhibits intracellular attachment plaque
–on the cytoplasmic side of the basal plasma membrane
–composed of plectin and BP 230 proteins
nintermediate filaments of the cytoskeleton bind to the proteins of the attachment plaque
ntransmembrane proteins integrins bind the attachment plaque to the extracellular matrix (basal lamina)
8.5.7
87
Explain the images
Bullous Pemphigoid
Caused by antibodies directed against proteins of the hemidesmosomal attachment plaques
88
\_\_\_\_\_\_\_ are
–form dynamic attachments
–linking actin filaments to extracellular matrix proteins
–role in attachment and migration of cells
FOCAL ADHESIONS
cytoplasmic face
–actin filaments
transmembrane region
–integrins
extracellular face
–Laminin and fibronectin
89
\_\_\_\_\_\_\_\_\_
§secrete product through ducts
\_\_\_\_\_\_\_\_\_
§lack duct system
§secrete product into connective tissue and from there to blood
§secretions called hormones
–EXOCRINE
–ENDOCRINE
90
Explain this image
## Footnote
8.5.7
Formation of glands from covering epithelia. During fetal development epithelial cells proliferate and penetrate the underlying connective tissue. They may-or may not-maintain a connection with the surface epithelium. When the connection is maintained, exocrine glands are formed; with the connection lost, endocrine glands are formed. Exocrine glands secrete to the body surface or gut via duct systems formed from the epithelial connection. The cells of endocrine glands, which secrete hormones can be arranged in cords or in follicles with lumens for storing the secretory product. From either the cords (left) or follicles (right) of endocrine cells, the secretory product is released outside the cells and picked up by the blood vessels for distribution throughout the body.
8.5.7
91
\_\_\_\_\_ explain this image
Section of large intestine showing goblet cells secreting mucus to the extracellular space. The mucus precursor stored in the cytoplasm of the goblet cells is also stained in a dark color. PAS-PT stain. Medium magnification.
8.5.7
92
Explain this image
Left: Diagram of a mucus-secreting intestinal goblet cell showing a typically constricted base, where the mitochondria and rough endoplasmic reticulum (RER) are located. The protein part of the glycoprotein complex is synthesized in the endoplasmic reticulum. A well-developed Golgi complex is present in the supranuclear region. (Redrawn after Gordon and reproduced, with permission, from Ham AW: Histology, 6th ed. Lippincott, 1969.) Right: Electron micrograph of a goblet cell from the small intestine. The rough endoplasmic reticulum (rER) is present mainly in the basal portion of the cell, while the cell apex is filled with light secretory vesicles or granules (SG) some of which are being discharged. The Golgi complex lies just above the nucleus. Typical columnar absorptive cells with microvillar borders (M) lie adjacent to the goblet cell. x7000. (Reproduced, with permission, from Junqueira LCU, Salles LMM. Ultra-Estrutura e Função Celular, Edgard Blücher, 1975.)
93
\_\_\_\_\_\_
–intestinal glands
AKA crypts of Lieberkühn
\_\_\_\_\_\_\_\_
–eccrine sweat glands
\_\_\_\_\_\_\_\_
–gastric glands
simple tubular
simple coiled tubular
simple branched tubular
94
What type of gland is this?
## Footnote
8.5.7
Intestinal glands (crypts of Lieberkuhn). Simple tubular
95
Wahtr type of glnd is this?
Eccrine sweat gland. Simple coiled tubular
96
Explain this image
## Footnote
8.5.7
Eccrine sweat gland, most numerous in body. Simple coiled tubular. S, secretory portion is lightly stained. D, ducts. Dust is darkly stained. Note accumulation of fat cells.
97
Explaiun this image
## Footnote
8.5.7
Simple branched tubular glands. Photomicrograph of a section of the gastric glands in the fundus of the stomach.
8.5.7
98
\_\_\_\_\_\_\_\_
–cardiac glands of stomach
simple branched acinar
Cardiac glands are found close to the esophagogastric junction (upper right corner). Cardiac glands are simple branched acinar. Mucous secreting.
99
\_\_\_\_\_\_
–as in pancreas
\_\_\_\_\_\_\_
–submucosal glands of Brunner (duodenum)
\_\_\_\_\_\_\_\_
–submandibular salivary gland
compound acinar
compound branched tubular
compound tubuloacinar
100
Explain this image
Compound acinar gland. Pancreas, serous acini, note cytoplasmic zymogen granules
101
Explain this image
Cross section of the Duodenum. V, villi; Muc, mucosa; MM, muscularis mucosae; SubM, submucosa; ME, muscularis externa; BGl, Brunner’s glands; D, duct through which the glands open into the lumen of the duodenum; S, serosa.
Brunner’s gland (BGl): compound branched tubular
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\_\_\_\_\_\_ are
–e.g. goblet cells, sublingual glands and surface cells of stomach
–cells are specialize in production of mucin protein
§mucin is highly glycosylated proteins
§therefore, it is viscus and slimy
§PAS positive
§water soluble, therefore, lost during tissue preparation
–nucleus of the cell is usually flattened against base of cell
Mucous glands
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Explain this image
Compound tubuloacinar glands of the soft palate, purely mucous.
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Explain this image
Higher magnification of the mucous gland. The acini reveales characteristic clear cytoplasm and basal nuclei.
105
Explain this image
Pancreas. Serous gland.
Purely serous
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Acini of some glands contain both serous and mucous cells (mixed)
nIn mixed acinus serous cells are more removed from lumen
–shaped as crescents or \_\_\_\_\_\_
§at periphery of the mucous acinus
–serous secretions reach duct via small intercellular channels or \_\_\_\_\_\_
§between mucous cells
DEMILUNES
CANALICULI
107
Explain this image
Sublingual gland. Mixed but mostly mucous. Many serous demilunes seen in this micrograph. The arrow point to the canaliculus, a small channel via which the serous demilune escorts its secretion to the lumen of the mixed acinus.
108
Explain this image
Submandibular gland, compound tubuloacinar gland, mixed, serous demilunes around the few mucous acini
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\_\_\_\_\_\_\_
–secretory material with adherent cytoplasm released from surface of cell
–e.g. secretion of fat droplets by mammary gland
\_\_\_\_\_\_\_\_
–The entire cell is sacrificed in producing secretion
–release of secretion accompanied by fragmentation and loss of integrity of entire cell
–lost cells are replaced
e.g. Sebaceous gland
Apocrine
Holocrine
110
Explain this image
This is a holocrine gland, because its product is secreted with the remnants of a dead cell. Cytoplasm of Secretory cells is filled with lipid droplets. Stem cells (arrows) in the base of the gland proliferate to replace the lost cells. Collagen fibers are stained in red. PSP stain. Medium magnification.
111
\_\_\_\_\_\_\_
–Secretion is stored in membrane-limited vesicles
–Membrane of vesicle fuses with the membrane of the secretory cell
Merocrine
112
Explain this image
–two different secretions released from the same cell by two different mechanisms
–e.g. mammary gland
§lipids – secreted by APOCRINE
§proteins – secreted by MEROCRINE
Secreting portion of mammary gland. Apocrine secretion (arrows) involves discharge of secretion with part of cytoplasm.
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