title: Early development of serotonin neuron in the rat brain as studied by immunohistochemistry combined with tryptophan administration.
abstract: Early differentiation of serotonin (5HT) neurons was studied by an immunohistochemical technique in the metencephalon of rat embryos of CR lengths of 6 mm to 22 mm. Pregnant dams were treated with tryptophan (100 mg/kg) and pargyline (100 mg/kg). The synthesis of 5HT after tryptophan loading first occurs at any stage in the premature cells located in the ependymal layer. The cells appearing at the later embryonic stage begin 5HT synthesis at an earlier developmental stage of neurons with greater capacity to produce 5HT. Two different processes were revealed for the development of 5HT neurons. Most of the 5HT neuroblasts first give off axonal processes and then begin to migrate toward the mantle layer with reversed rotation. Some of the 5HT neuroblasts, later generated in the rostral pons in particular, display characteristic transformation without notable migration. After sending out of axonal processes ventrally, the apical processes are transformed into a number of dendritic processes directed toward the ventricular surface.
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D002454:Cell Differentiation; D002465:Cell Movement; D005260:Female; D006651:Histocytochemistry; D008431:Maternal-Fetal Exchange; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*; D014364:Tryptophan / Q000494:pharmacology / Q000502:physiology*
chemical_list: D012701:Serotonin; D014364:Tryptophan