Development and localization of enkephalin and substance P in the nucleus of tractus solitarius in the medulla oblongata of human fetuses.
The presence of enkephalin and substance P-positive neurons and fibers were studied by immunohistochemistry (peroxidase-antiperoxidase or avidin-biotin-peroxidase complex methods) in 26 human fetuses ranging from 11 weeks of gestation to 40 weeks of gestation. Enkephalin-positive neurons were localized in the commissural, medial and intermediate subnuclei as early as 11-12 weeks' gestation. Positive enkephalin fibers were localized around 12 weeks' gestation and in many subnuclei, notably the medial, commissural, intermediate, ventrolateral, ventral and dorsolateral subnuclei. Substance P-positive neurons were localized in the commissural and medial subnuclei around gestation age 13 weeks. Positive substance P fibers appeared even earlier, around 11 weeks of gestation in many subnuclei, notably the medial, intermediate, ventral, ventrolateral and dorsolateral subnuclei. Increase in both enkephalin- and substance P-positive fibers was evident in the later stages of development (e.g. around 26 weeks of gestation). The importance of the early appearance of enkephalin and substance P neurons and fibers of the pain pathways in the major subnuclei connecting with the cardiovascular, gastrointestinal and respiratory functions in the human has to be stressed.
Yew
D T
DT
Department of Anatomy, Chinese University of Hong Kong, Shatin.
Luo
C B
CB
Zheng
D R
DR
Guan
Y L
YL
Lin
Y Q
YQ
Chen
W Z
WZ
D005314:Embryonic and Fetal Development; D004745:Enkephalins / Q000378:metabolism*; D005865:Gestational Age; D006801:Humans; D007150:Immunohistochemistry; D008526:Medulla Oblongata / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*
D004745:Enkephalins; D013373:Substance P