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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 ]
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 .
Thrombolites are poorly laminated or non-laminated clotted structures formed by cyanobacteria, common in the fossil record and in modern sediments. [18] There is evidence that thrombolites form in preference to stromatolites when foraminifera are part of the biological community. [33]
Ancient giant stromatolites used to be widespread in Earth’s Precambrian era, which encompasses the early time span of around 4.6 billion to 541 million years ago, but now they are sparsely ...
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.
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 ]
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 ...
The blood–brain barrier is formed by the brain capillary endothelium and excludes from the brain 100% of large-molecule neurotherapeutics and more than 98% of all small-molecule drugs. [28] Overcoming the difficulty of delivering therapeutic agents to specific regions of the brain presents a major challenge to treatment of most brain disorders.