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Thrombolites have a clotted structure without the laminae of stromatolites. Each clot within a thrombolite mound is a separate cyanobacterial colony . The clots are on the scale of millimetres to centimetres and may be interspersed with sand , mud or sparry carbonate . [ 1 ]
The connection between grazer and stromatolite abundance is well documented in the younger Ordovician evolutionary radiation; stromatolite abundance also increased after the Late Ordovician mass extinction and Permian–Triassic extinction event decimated marine animals, falling back to earlier levels as marine animals recovered. [30]
Oncolites are very similar to stromatolites, but, instead of forming columns, they form approximately spherical structures. [1] The oncoids often form around a central nucleus, such as a shell fragment, [ 2 ] and a calcium carbonate structure is deposited by encrusting microbes .
"Spongiostromata" is an antiquated form taxon that refers primarily to fossil cyanobacteria. "Spongiostromate" is also used to describe stromatolites and oncolites that do not preserve clear tubules or other cellular microstructure.
Image of the human brain showing sulci, gyri, and fundi shown in a Coronal section. Specific terms are used to represent the gross anatomy of the brain: A gyrus is an outward folding of the brain, for example the precentral gyrus. A sulcus is an inward fold, or valley in the brain's surface - for example the central sulcus. Additional terms ...
Brain cells make up the functional tissue of the brain. The rest of the brain tissue is the structural stroma that includes connective tissue such as the meninges , blood vessels , and ducts. The two main types of cells in the brain are neurons , also known as nerve cells, and glial cells , also known as neuroglia. [ 1 ]
The cerebral cortex, also known as the cerebral mantle, [1] is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals.It is the largest site of neural integration in the central nervous system, [2] and plays a key role in attention, perception, awareness, thought, memory, language, and consciousness.
The striatum (pl.: striata) or corpus striatum [5] is a cluster of interconnected nuclei that make up the largest structure of the subcortical basal ganglia. [6] The striatum is a critical component of the motor and reward systems; receives glutamatergic and dopaminergic inputs from different sources; and serves as the primary input to the rest of the basal ganglia.