MAGNOCELLULAR NEUROSECRETORY CELL Meaning and
Definition
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A magnocellular neurosecretory cell is a specialized type of neuron found primarily in two key regions of the brain: the paraventricular nucleus (PVN) and the supraoptic nucleus (SON) of the hypothalamus. These neurons play a crucial role in the secretion of several important hormones into the bloodstream.
Structurally, magnocellular neurosecretory cells possess long, branched axons that extend from the PVN and SON into the posterior pituitary gland. They are classified as "magnocellular" due to their larger size compared to other neurons in the brain. These cells have an elongated shape with a prominent cell body and numerous dendritic branches.
The main function of magnocellular neurosecretory cells is the synthesis and release of two critical hormones: oxytocin and vasopressin (also known as antidiuretic hormone, ADH). Oxytocin is involved in various physiological processes, including uterine contractions during labor and lactation. Vasopressin primarily regulates water balance by promoting water reabsorption in the kidneys and constriction of blood vessels.
These cells are stimulated by different physiological signals, such as changes in blood osmolarity or stretch receptors in the uterus during childbirth. Once activated, magnocellular neurosecretory cells release oxytocin or vasopressin from their axon terminals into the posterior pituitary gland, where the hormones are stored and later released into the bloodstream.
Overall, magnocellular neurosecretory cells are key players in maintaining homeostasis, regulating various bodily functions, and influencing behavior through the release of oxytocin and vasopressin.
