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The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. [1] In the human brain the brainstem is composed of the midbrain , the pons , and the medulla oblongata . [ 1 ]
The pedunculopontine nucleus (PPN) or pedunculopontine tegmental nucleus (PPT or PPTg) is a collection of neurons located in the upper pons in the brainstem. [1] [2] It is involved in voluntary movements, [3] arousal, and provides sensory feedback to the cerebral cortex and one of the main components of the ascending reticular activating system.
The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses.
Although this epithelium is referred to as squamous, many cells within the layers may not be flattened; this is due to the convention of naming epithelia according to the cell type at the surface. In the deeper layers, the cells may be columnar or cuboidal. [1] There are no intercellular spaces.
Squamous Squamous cells have the appearance of thin, flat plates that can look polygonal when viewed from above. [5] Their name comes from squāma, Latin for "scale" – as on fish or snake skin. The cells fit closely together in tissues, providing a smooth, low-friction surface over which fluids can move easily.
The basal lamina is made and maintained by the cells that sit on it. It acts as a point of attachment for cells. However, it can also have other function such as a permeability barrier in the glomerulus (urine production). Some of the matrix molecules (of the basal lamina) mediate synaptic adhesion in neuromuscular synapses. [8]
Neural organoids are created by culturing pluripotent stem cells into a three-dimensional culture that can be maintained for years. [1] [2] The brain is an extremely complex system of heterogeneous tissues and consists of a diverse array of neurons and glial cells. This complexity has made studying the brain and understanding how it works a ...
Within the cardiovascular system such as lining capillaries or the inside of the heart, simple squamous epithelium is specifically called the endothelium. [3] Cells are flat with flattened and oblong nuclei. It is also called pavement epithelium due to its tile-like appearance. This epithelium is associated with filtration and diffusion.