13.1 POJA-La0303+L4648+4649
Title: Brain capillaries with continuous endothelium
Description:
(A): Immunoperoxidase staining for collagen IV in brain capillaries of a rat 1 day postnatal. (1) Endothelium of the vein. (2) Collagen IV collar surrounding the vein. (3) Nerve tissue cells. Collagen IV is specifically only detected in the basal lamina surrounding blood vessels. Note that pericytes are totally wrapped in basement membrane material (arrows).
(B): Electron micrograph of a capillary of the Blood-Brain barrier (BBB) in the neuropil of the epiphysis or pineal gland (gerbil). Capillary lumen (7) with continuous endothelium and the astroglial cell completely wraps with their processes the capillary. Swollen processes (8) of neuroglial cells (nucleus, 9), (10) surrounding neuropil contains dendrites, axons, no neuronal perikarya.
(C): Electron micrograph of a capillary in spinal cord, rat. (4) Lumen of the capillary with a continuous endothelium (6), adjacent basal lamina fused with electron-light end-feet of astroglial cells (BBB). The capillary is located in between the neuropil with glia cells and neurites. (6) Nucleus of astrocyte and (5) neuropil. Continuous endothelium lines the capillaries in brain tissue, there is little pinocytosis and zonula occludens junctions connect the cells. A basal lamina is shared by pericytes and enveloping cytoplasmic processes of astroglia cells i.e. astrocytes. The fibrous and protoplasmic astrocytes completely wrap with their processes the capillary and contribute to the BBB. (By courtesy of P. Buma PhD former research fellow Department of Anatomy).
Background: Capillaries with continuous endothelium are most common with a closed basal membrane and few pericytes i.e. somatic capillaries in muscle and dermis. In nervous tissue these capillaries are more specialised and the continuous endothelium is surrounded by an uninterrupted basal lamina with some pericytes, and covered by perivascular glial end-feet (so-called Blood-Brain-Barrier).
In light microscopy a basement membrane (20-50 nm thick) separates endothelial cells from the surrounding neuropil in the brain. Ultrastructurally the basement membrane is represented by a basal lamina (lamina basalis), it is a specialised form of extracellular matrix (ECM) and often referred to as the type IV matrix. The basal lamina is composed of three sublayers: a clear or lucid layer (lamina lucida, lamina rara externa, ca. 60 nm thick) close to the endothelial cells, an intermediate electron-dense layer (lamina densa, average 30-100 nm thick) and a thin hardly electron-dense lamina rara interna (ca. 10 nm) closer to the neural tissue compartment. Within the electron-lucid layer laminins, integrins, entactins and dystroglycan are localised. The lamina densa contains a network of collagen IV coated with perlecan (a heparan sulfate proteoglycan).
Keywords/Mesh: cardiovascular system. vascularisation, brain, capillary, endothelium, basal lamina, pericyte, glia cell , astroglial cell , Blood-Brain barrier, pineal gland, electron microscopy, histology, POJA collection
Title: Brain capillaries with continuous endothelium
Description:
(A): Immunoperoxidase staining for collagen IV in brain capillaries of a rat 1 day postnatal. (1) Endothelium of the vein. (2) Collagen IV collar surrounding the vein. (3) Nerve tissue cells. Collagen IV is specifically only detected in the basal lamina surrounding blood vessels. Note that pericytes are totally wrapped in basement membrane material (arrows).
(B): Electron micrograph of a capillary of the Blood-Brain barrier (BBB) in the neuropil of the epiphysis or pineal gland (gerbil). Capillary lumen (7) with continuous endothelium and the astroglial cell completely wraps with their processes the capillary. Swollen processes (8) of neuroglial cells (nucleus, 9), (10) surrounding neuropil contains dendrites, axons, no neuronal perikarya.
(C): Electron micrograph of a capillary in spinal cord, rat. (4) Lumen of the capillary with a continuous endothelium (6), adjacent basal lamina fused with electron-light end-feet of astroglial cells (BBB). The capillary is located in between the neuropil with glia cells and neurites. (6) Nucleus of astrocyte and (5) neuropil. Continuous endothelium lines the capillaries in brain tissue, there is little pinocytosis and zonula occludens junctions connect the cells. A basal lamina is shared by pericytes and enveloping cytoplasmic processes of astroglia cells i.e. astrocytes. The fibrous and protoplasmic astrocytes completely wrap with their processes the capillary and contribute to the BBB. (By courtesy of P. Buma PhD former research fellow Department of Anatomy).
Background: Capillaries with continuous endothelium are most common with a closed basal membrane and few pericytes i.e. somatic capillaries in muscle and dermis. In nervous tissue these capillaries are more specialised and the continuous endothelium is surrounded by an uninterrupted basal lamina with some pericytes, and covered by perivascular glial end-feet (so-called Blood-Brain-Barrier).
In light microscopy a basement membrane (20-50 nm thick) separates endothelial cells from the surrounding neuropil in the brain. Ultrastructurally the basement membrane is represented by a basal lamina (lamina basalis), it is a specialised form of extracellular matrix (ECM) and often referred to as the type IV matrix. The basal lamina is composed of three sublayers: a clear or lucid layer (lamina lucida, lamina rara externa, ca. 60 nm thick) close to the endothelial cells, an intermediate electron-dense layer (lamina densa, average 30-100 nm thick) and a thin hardly electron-dense lamina rara interna (ca. 10 nm) closer to the neural tissue compartment. Within the electron-lucid layer laminins, integrins, entactins and dystroglycan are localised. The lamina densa contains a network of collagen IV coated with perlecan (a heparan sulfate proteoglycan).
Keywords/Mesh: cardiovascular system. vascularisation, brain, capillary, endothelium, basal lamina, pericyte, glia cell , astroglial cell , Blood-Brain barrier, pineal gland, electron microscopy, histology, POJA collection