Lamina cells shape

Neither Fleischer (1915-1922) nor Brotherus (1925) provided subdivisions of the Amblystegiaceae above the genus level. Their generic subdivisions were clearly based on a few, easily observable characters, such as leaf orientation and shape, development of the vegetative leaf costa and leaf border, leaf lamina cell shape, the presence or absence of paraphyllia, and the habitat of the species (cf., Brotherus, 1925). 

Intermediate filaments are about lOnm in diameter, and are more stable (strongly bound) than actin filaments. Like actin filaments they function in the maintenance of cell shape by bearing tension. Intermediate filaments organise the internal tridimensional structure of the ceU, anchoring organelles and serving as structural components of the nuclear lamina (a dense fibrillar network inside the nucleus) and sarcomeres. They also participate in some cell-cell and cell-matrix junctions. 

The third mucosal layer is that lining the entire length of the small intestine and which represents a continuous sheet of epithelial cells. These epithelial cells (or enterocytes) are columnar in shape, and the luminal cell membrane, upon which the microvilli reside, is called the apical cell membrane. Opposite this membrane is the basal (or basolateral) plasma membrane, which is separated from the lamina propria by a basement membrane. A sketch of this cell is shown in Fig. 5. The primary function of the villi is absorption. 

Rotaviruses are double-stranded wheel-shaped RNA viruses. These strains cause diarrhea by infecting the enterocyts of the villi in the small intestine. Changes to the villi include shortening of villus height, crypt hyperplasia, and mononuclear cell infiltration of the lamina propria. Diarrhea results from decreased absorption across intestinal mucosal surface. ... 

A FIGURE 6-16 Laminin, a heterotrimeric multiadhesive matrix protein found in all basal laminae, (a) Schematic model showing the general shape, location of globular domains, and coiled-coil region in which laminin s three chains are covalently linked by several disulfide bonds. Different regions of laminin bind to cell-surface receptors and various matrix components. 

Many of the cells in tissues are embedded in an extracellular matrix that fills the spaces between cells and binds cells and tissue together. In so doing, the extracellular matrix aids in determining the shape of tissues as well as the nature of the partitioning between tissue types. In the skin, loose connective tissue beneath epithelial cell layers consists of an extracellular matrix in which fibroblasts, blood vessels, and other components are distributed (Fig 49.1). Other types of connective tissue, such as tendon and cartilage, consist largely of extracellular matrix, which is principally responsible for their structure and function. This matrix also forms the sheetlike basal laminae, or basement membranes, on which layers of epithelial cells rest, and which act as supportive tissue for muscle cells, adipose cells, and peripheral nerves. 

SMC (lamellar) ceils are co-segregated in the tunica media [8,9]. The former cell type lacks a basement membrane, myofilaments and dense bodies. In addition, bovine aorta and pulmonary artery SMC can have distinct structural profiles as regards shape, location, cell orientation and pattern of elastic laminae [10-13]. 

In both smokers and non-smokers typical basal cells were more numerous than atypical basal cells, which were distinguished by their spindle-shaped nucleus, polar cytoplasm, and processes that extended along the basal lamina (Baldwin 1994). The nucleus of the atypical basal cell was consistently closer to the muco-cihary surface than was the nucleus of the typical basal cell. 

In this respect there are striking similarities to morphological characteristics. It is, for example, under most circumstances obviously advantageous for a higher plant to spread the chlorophyll-containing cells by formation of a leaf lamina. But in most cases there is no rationale for the details of the shape of the lamina, which in the different plant species may be smooth-edged, toothed, serrate, divided, lobed, etc. 

In large bronchi the cartilages are irregular in shape but frequent enough to be found in any plane. In small bronchi, they are less frequent and may be missed in transverse section. The bronchioli lack cartilage. The epithelium in the major bronchi and proximal bronchioles is a ciliated pseudostratified epithelium, with ciliated columnar cells as the predominant cell type. In the distal bronchioles the epithelium consists of a single cell layer. The ciliated columnar cells reach the basal lamina with slender basal processes [43]. 

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