10.3 POJA-L2519+2520+2521+2522+2523
Title: Collagen IV and desmin expression in skin
Description:
Skin of external ear, postnatal rat, immunoperoxidase staining with DAB and antibodies against collagen IV, neurofilament
and desmin, counterstained with hematoxylin.
(A): Epidermis, collagen IV.
(B): Hair follicles in dermis, collagen IV.
(C): Sweat glands in dermis, collagen IV.
All pictures in (A - C) illustrate clearly that collagen IV is apposed to the basal membrane surrounding the epithelial cells of
the skin and sebaceous glands, but also around the blood vessels. In light microscopy a basement membrane separates
the basal side of polarized epithelial or endothelial cells from the surrounding connective tissue (a.o. proper lamina).
It encompasses two fused membranes i.e. the basal lamina (secreted by epithelial cells) and a close apposed reticular lamina
(secreted by other cells). The latter is absent if a connective compartment lacks (e.g. kidney glomerulus, heart muscle).
(D): Nerve fibers in dermis, RNF. Cross- and longitudinal sectioned nerve bundles between sweat glands in the dermis
(E): Striated muscles in dermis, desmin. The intermediate filament desmin is a structural component of cardiac, skeletal and
smooth muscle cells, found near the Z line in sarcomeres.
Background:
Collagen IV is a structural component of the basement membrane (in light microscopy) or of the basal membrane (in electron
microscopy). Ultrastructurally a basal lamina is composed of three sublayers:
(1) a clear or lucid layer (lamina lucida, lamina rara externa, ca. 60 nm thick) close to the epithelial cells;
(2) an intermediate electron-dense layer (lamina densa, average 30-100 nm thick);
(3) a thin hardly electron-dense lamina rara interna (ca. 10 nm) closer to the connective tissue compartment.
Within the electron-lucid layer laminins, integrins, entactins and dystroglycan are localized.
The lamina densa contains a network of collagen IV coated with perlecan (a heparan sulfate proteoglycan).
From the basal lamina anchoring fibrils type VII collagen extend from the rara interna with microfibrils into the apposed
fibroreticular lamina (lamina fibroreticularis or sublamina densa zone, ca. 200-500 nm) containing type I/III collagen fibrils.
The laminins form a family of large, non-collageneous glycoproteins that are secreted and incorporated into cell-associated ECM.
They are localized in the lucid layer and anchor cell surfaces to basal laminae, form independent networks and associate with
type IV collagen networks via perlecan and entactin.
Integrins are transmembrane receptors that mediate attachment between cells and surrounding tissues and play a role in cell
signalling. They regulate cell shape, motility and bind cell surface and ECM components such as laminin, collagen, fibronectin etc.
Entactin belongs to the nidogen family, nidogen-1/-2 is a basal lamina glycoprotein that a.o. interacts with laminin, type IV collagen. Dystroglycan is a transmembrane protein, highly glycosylated and belongs to the dystrophin-associated glycoprotein complex.
It is a receptor for multiple ECM molecules (a.o. laminin, perlecan) and plays a role in linking the ECM molecules to the actin
cytoskeleton via the actin-binding protein dystrophin.
Keywords/Mesh: skin, collagen IV, desmin, neurofilament, histology, electron microscopy, POJA collection
Title: Collagen IV and desmin expression in skin
Description:
Skin of external ear, postnatal rat, immunoperoxidase staining with DAB and antibodies against collagen IV, neurofilament
and desmin, counterstained with hematoxylin.
(A): Epidermis, collagen IV.
(B): Hair follicles in dermis, collagen IV.
(C): Sweat glands in dermis, collagen IV.
All pictures in (A - C) illustrate clearly that collagen IV is apposed to the basal membrane surrounding the epithelial cells of
the skin and sebaceous glands, but also around the blood vessels. In light microscopy a basement membrane separates
the basal side of polarized epithelial or endothelial cells from the surrounding connective tissue (a.o. proper lamina).
It encompasses two fused membranes i.e. the basal lamina (secreted by epithelial cells) and a close apposed reticular lamina
(secreted by other cells). The latter is absent if a connective compartment lacks (e.g. kidney glomerulus, heart muscle).
(D): Nerve fibers in dermis, RNF. Cross- and longitudinal sectioned nerve bundles between sweat glands in the dermis
(E): Striated muscles in dermis, desmin. The intermediate filament desmin is a structural component of cardiac, skeletal and
smooth muscle cells, found near the Z line in sarcomeres.
Background:
Collagen IV is a structural component of the basement membrane (in light microscopy) or of the basal membrane (in electron
microscopy). Ultrastructurally a basal lamina is composed of three sublayers:
(1) a clear or lucid layer (lamina lucida, lamina rara externa, ca. 60 nm thick) close to the epithelial cells;
(2) an intermediate electron-dense layer (lamina densa, average 30-100 nm thick);
(3) a thin hardly electron-dense lamina rara interna (ca. 10 nm) closer to the connective tissue compartment.
Within the electron-lucid layer laminins, integrins, entactins and dystroglycan are localized.
The lamina densa contains a network of collagen IV coated with perlecan (a heparan sulfate proteoglycan).
From the basal lamina anchoring fibrils type VII collagen extend from the rara interna with microfibrils into the apposed
fibroreticular lamina (lamina fibroreticularis or sublamina densa zone, ca. 200-500 nm) containing type I/III collagen fibrils.
The laminins form a family of large, non-collageneous glycoproteins that are secreted and incorporated into cell-associated ECM.
They are localized in the lucid layer and anchor cell surfaces to basal laminae, form independent networks and associate with
type IV collagen networks via perlecan and entactin.
Integrins are transmembrane receptors that mediate attachment between cells and surrounding tissues and play a role in cell
signalling. They regulate cell shape, motility and bind cell surface and ECM components such as laminin, collagen, fibronectin etc.
Entactin belongs to the nidogen family, nidogen-1/-2 is a basal lamina glycoprotein that a.o. interacts with laminin, type IV collagen. Dystroglycan is a transmembrane protein, highly glycosylated and belongs to the dystrophin-associated glycoprotein complex.
It is a receptor for multiple ECM molecules (a.o. laminin, perlecan) and plays a role in linking the ECM molecules to the actin
cytoskeleton via the actin-binding protein dystrophin.
Keywords/Mesh: skin, collagen IV, desmin, neurofilament, histology, electron microscopy, POJA collection