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The cell itself consists of two halves, each containing an essentially flat plate, or valve, and marginal connecting, or girdle band. One half, the hypotheca, is slightly smaller than the other half, the epitheca. Diatom morphology varies. Although the shape of the cell is typically circular, some cells may be triangular, square, or elliptical.
In gram-positive bacteria, the cytoplasmic membrane is only surrounded by a thick cell wall of peptidoglycan. By contrast, the envelope of gram-negative bacteria is more complex and consists (from inside to outside) of the cytoplasmic membrane, a thin layer of peptidoglycan, and an additional outer membrane, also called the lipopolysaccharide ...
The microscopic layers of that shield appear to evolutionary biologists, "like they are composed of little tooth-like structures." [4] Neil Shubin writes: "Cut the bone of the [ostracoderm] skull open…pop it under a microscope and…you find virtually the same structure as in our teeth. There is a layer of enamel and even a layer of pulp.
For many years the diatoms—treated either as a class (Bacillariophyceae) or a phylum (Bacillariophyta)—were divided into just 2 orders, corresponding to the centric and the pennate diatoms (Centrales and Pennales; alternative names Biddulphiales and Bacillariales, as used e.g. in Lee, 1989). [9]
The outermost layer of the gastrointestinal wall consists of several layers of connective tissue and is either of serosa (below the diaphragm) or adventitia above the diaphragm. [4] [1] [5] Regions of the gastrointestinal tract within the peritoneum (called Intraperitoneal) are covered with serosa. This structure consists of connective tissue ...
The mesoderm, which is another layer of the trilaminar germ disc, holds the tubes together and the lateral plate mesoderm, the middle layer of the germ disc, splits to form a visceral layer associated with the gut and a parietal layer, which along with the overlying ectoderm, forms the lateral body wall. The space between the visceral and ...
Insoluble fiber, on the other hand, adds bulk to the stool and helps move food through the digestive system, keeping you regular. Most Americans don’t consume enough fiber on a daily basis.
Placozoans have only three anatomical parts as tissue layers inside its body: the upper, intermediate (middle) and lower epithelia. There are at least six different cell types. [ 32 ] The upper epithelium is the thinnest portion and essentially comprises flat cells with their cell body hanging underneath the surface, and each cell having a ...