7/26/2023 0 Comments Loop fingerprint![]() The neuro-ectoderm theory describes an interdependent relationship between the neurological map and the pattern of primary ridges. Once the interaction of forces is great enough, a buckling instability occurs and further cell proliferation may increase the depth.The nervous system is also involved in this process.Differential growth of the cellular layers of the skin creates resistive boundary forces, causing a compressive effect.Ridges form perpendicular to lines of greatest stress. The mechanical instability theory regards ridge formation as a consequence of a buckling process. There are two main theories that aim to explain the processes underlying friction ridge formation. What are the theories of friction ridge development? By end of second trimester, sweat ducts and pores appear along epidermal ridges.Sweat glands and epidermal– dermal ridge system continue to mature and enlarge.Volar pad regression and friction ridge development continue by week 16 permanent minutiae are set.Basal layer becomes more prominent and forms folds of epidermis into dermis (primary ridges).Volar skin is layered epidermis on top of shapeless fibrous dermis.Volar pads less prominent then disappear friction ridge units develop.At 7–8 weeks volar pads begin to form from mesoderm.Limbs rapidly develop from about 4 weeks: arms, legs, knees, elbows, fingers, toes seen at about 8 weeks.Endoderm – forms other major organ systems including gastrointestinal tract, respiratory tract, urinary tract.Mesoderm – forms connective tissue of dermis.Ectoderm – forms the epidermis, including friction ridge skin.Gastrulation – early single ball of cells reorganises into three primary tissues. ![]() Fertilisation of egg initiates embryonal development. ![]() They undergo various phases, of which crucial events occur by the early weeks of the second trimester. Fingerprints develop during early fetal life. ![]()
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