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Abstract closure or interior operators can be used to define a generalized topology on the lattice. Since neither unions nor the empty set appear in the requirement for a Moore closure operator, the definition may be adapted to define an abstract unary operator : on an arbitrary poset.
Examples of this form of articulation are found in the hip, where the round head of the femur (ball) rests in the cup-like acetabulum (socket) of the pelvis; and in the shoulder joint, where the rounded upper extremity of the humerus (ball) rests in the cup-like glenoid fossa (socket) of the shoulder blade. [2]
Together with an alpha-beta catenin complex, the cadherin can bind to the microfilaments of the cytoskeleton of the cell. This allows for homophilic cell–cell adhesion. [18] The β-catenin–α-catenin linked complex at the adherens junctions allows for the formation of a dynamic link to the actin cytoskeleton. [19]
Joints can also be classified based on their anatomy or on their biomechanical properties. According to the anatomic classification, joints are subdivided into simple and compound, depending on the number of bones involved, and into complex and combination joints: [19] Simple joint: two articulation surfaces (e.g. shoulder joint, hip joint)
The initiation of endochondral ossification starts by proliferation and condensation of mesenchymal cells in the area where the bone will eventually be formed. Subsequently, these mesenchymal progenitor cells differentiate into chondroblasts, which actively synthesize cartilage matrix components.
Examples: The thumb is on the radial side of the hand (the same as saying the lateral side); the ulnar side of the wrist is the side toward the little finger (medial side). Ventral and dorsal , which describe structures derived from the front (ventral) and back (dorsal) of the embryo , before limb rotation.
Intercalated discs are complex structures that connect adjacent cardiac muscle cells. The three types of cell junction recognised as making up an intercalated disc are desmosomes, fascia adherens junctions, and gap junctions. [2] Fascia adherens are anchoring sites for actin, and connect to the closest sarcomere. [3]
A simplicial 3-complex. In mathematics, a simplicial complex is a structured set composed of points, line segments, triangles, and their n-dimensional counterparts, called simplices, such that all the faces and intersections of the elements are also included in the set (see illustration).