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Showing posts from March, 2024

Comparison between tract and nerve

  Comparison between tract and nerve Nerve Nerve contain bundle of axons (nerve fibers) in the peripheral nervous system (PNS) that transmits signals between the central nervous system (CNS) and other parts of the body. It is the most important part of peripheral nervous system Location: Peripheral nervous system. Structure: Made of axons, connective tissue layers (endoneurium: axon is surrounded by it , perineurium: bundle of axons are surrounded by it, epineurium: whole nerve trunk is surrounded by it), and blood vessels. It gets myelination by Schwann cell   Function: Carries sensory signals to the CNS (afferent) from peripheral part of body or motor signals carry from from the CNS (efferent) to target organs like skeletal muscle, cardiac muscle, smooth muscle or glands Example: Sciatic nerve, median nerve, except optic nerve (though optic nerve is technically part of CNS in develop...

Difference between location, functions & development of different skin cells

  Difference between location, functions & development of different skin cells Cells of skin Location Functions Development Keratinocytes stratum basale  It forms barrier against environmental damage by heat, UV radiation, dehydration, pathogenic bacteria, fungi, parasites, and viruses. Surface ectoderm Melanocytes Stratum basale Melanocytes are well known for their role in skin pigmentation, and their ability to produce and distribute melanin has been studied extensively Neural crest Langerhans cells Stratum spinosum These cells act as the outermost guard of the cutaneous immune system and are likely to induce the first reactions against pathogens encountered via the skin Fetal Langerhans cells from Primitive yolk sac in fetal life , in adult Langerhans cells   from feta...

Difference between development of ovary and testis

Difference between development of ovary and testis                                                                Development of ovary   1.         intermediate mesoderm form urogenital ridge, a longitudinal elevation at the dorsal body wall of fetus 2.        The coelomic epithelium and underlying mesoderm of the urogenital ridge proliferate to form the gonada ridge 3.        The coelomic epithelium forms irregular primary sex cords and incorporate primordial germ cells which migrate from the wall of yolk sac 4.        The primary sex cord extends deep to medulla and dissociate into irregular cell clusters which eventually degenerate and replace by vascular stroma, the ovarian medulla. 5. ...