Structures connecting keratinocyte cells to the extracellular matrix
Hemidesmosome
Ultrastructure of tracheal hemidesmosomes in mice. In a normal mouse (a) there are well-defined, organized hemidesmosomes with darkened areas in the lamina densa abutting the hemidesmosome (arrows). In contrast, hemidesmosomes in Lamc2 -/- tracheas (b) are less organized, the intracellular component is more diffuse, and the lamina densa directly below the hemidesmosomal areas lacks the electron density seen in the littermate control (arrows). From Nguyen et al., 2006.[1]
Hemidesmosomes are very small stud-like structures found in keratinocytes of the epidermis of skin that attach to the extracellular matrix. They are similar in form to desmosomes when visualized by electron microscopy; however, desmosomes attach to adjacent cells. Hemidesmosomes are also comparable to focal adhesions, as they both attach cells to the extracellular matrix. Instead of desmogleins and desmocollins in the extracellular space, hemidesmosomes utilize integrins. Hemidesmosomes are found in epithelial cells connecting the basal epithelial cells to the lamina lucida, which is part of the basal lamina.[2] Hemidesmosomes are also involved in signaling pathways, such as keratinocyte migration or carcinoma cell intrusion.[3]