(1) Maulana Azad Medical College, New Delhi, India
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The Enteric nervous system (ENS) is a network which contains reflex circuits that detect the physiological condition of the gastrointestinal tract, integrate the information, and provide outputs to control gut motility, exocrine and endocrine secretions, microcirculation, immune and inflammatory processes. Elucidation of the mechanisms of ENS development and function allow the development of new approaches to the diagnosis, therapy, and prevention of human disorders of gastrointestinal motility. Therefore it is essential to understand the normal development of the ENS in human during prenatal period. This study henceforth aimed to determine the histogenesis of the enteric neurons.
Materials and methods
This study was done on human fetuses to evaluate the histogenesis of the enteric neurons at various gestational ages (10-28 weeks) by H&E, Masson’s Trichome Silver impregnation and immunohistochemistry for synaptophysin .
The earliest fetus studied in the present study was 10-12 weeks by which most of the neural crest cells have migrated from towards the developing gut. The neural crest derived cells were arranged as a band of scattered neurons in the serosa on the outer aspect of the developing muscualris externa where the myenteric plexus would finally form. The migrating neurons moved from the periphery of the developing muscularis externa towards the submucosal region traversing through connective tissue pathways through the muscle layers. Imunohistochemistry for synaptic marker synaptophysin was positive first at 28 weeks of gestation.
As the stomach progressed through the gestational ages, the cells became aggregated into more organized ganglionic groupings from a scattered collection of neurons at the beginning of the second trimester. Submucosal plexus was seen to secondary to the myenteric plexus. Progressive organization was seen in the myenteric and submucosal plexuses during various gestational ages. By 28 weeks of gestation, the human stomach showed organized enteric neurons positioned at intermuscular and submucosal regions with a positive for synaptic vesicle protein synaotophysin.