title: Appearance of tyrosine hydroxylase immunoreactivity in the human embryo.
abstract: Tyrosine hydroxylase was detected immunohistochemically in 3 human fetuses aged 5 1/2-6, 9-10 and 13-14 weeks. In the youngest fetus only the developing sympathetic chains were stained. By 9-10 weeks sympathetic terminals, adrenal medulla, carotid bodies, locus ceruleus, substantia nigra and basal ganglia showed positive reactions. In the oldest fetus a dense sympathetic innervation was present in the ductus venosus. Catecholaminergic neuronal systems, including their terminal axons, are well developed by 2 1/2 months of human gestation. PAP immunohistochemistry has the advantage of being applicable to archival formalin-fixed, paraffin-embedded tissue.
mesh_terms: D001921:Brain / Q000196:embryology / Q000201:enzymology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007124:Immunoenzyme Techniques; D009420:Nervous System / Q000196:embryology* / Q000201:enzymology; D011247:Pregnancy; D013564:Sympathetic Nervous System / Q000196:embryology / Q000201:enzymology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D014446:Tyrosine 3-Monooxygenase