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During early embryonic development of the vertebrate, the dorsal ectoderm becomes specified to give rise to the epidermis and the nervous system; a part of the dorsal ectoderm becomes specified to neural ectoderm to form the neural plate which gives rise to the nervous system.
After formation of the tube, the brain forms into three sections; the hindbrain, the midbrain, and the forebrain. The types of neuroectoderm include: Neural crest. pigment cells in the skin; ganglia of the autonomic nervous system; dorsal root ganglia. facial cartilage; aorticopulmonary septum of the developing heart and lungs; ciliary body of ...
At the start of this process, the developing embryo has divided into many cells, forming a hollow ball called the blastula. The blastula is polar, and its two halves are called the animal hemisphere and vegetal hemisphere. It is the animal hemisphere will eventually become the ectoderm. [2]
The development of the nervous system in humans, or neural development, or neurodevelopment involves the studies of embryology, developmental biology, and neuroscience.These describe the cellular and molecular mechanisms by which the complex nervous system forms in humans, develops during prenatal development, and continues to develop postnatally.
Neural crest cells form ganglia above each rhombomere. The early neural tube is primarily composed of the germinal neuroepithelium, later called the ventricular zone, which contains primary neural stem cells called radial glial cells and serves as the main source of neurons produced during brain development through the process of neurogenesis ...
The formation of the neural tube polarizes the neuroepithelial cells by orienting the apical side of the cell to face inward, which later becomes the ventricular zone, and the basal side is oriented outward, which contacts the pia, or outer surface of the developing brain. [3] As part of this polarity, neuroepithelial cells express prominin-1 ...
While the cells that remain as the neural tube form the brain and spinal cord, the other cells that were part of the neural plate migrate away from the tube as neural crest cells. After an epithelial–mesenchymal transition, these cells form the autonomic nervous system and certain cells of the peripheral nervous system. [7]
The nail matrix is the active tissue (or germinal matrix) that generates cells. The cells harden as they move outward from the nail root to the nail plate. [3] The nail matrix is also known as the matrix unguis, keratogenous membrane, or onychostroma. [4] It is the part of the nail bed that is beneath the nail and contains nerves, lymph and ...