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.
Department of Anatomy, Chinese University of Hong Kong, Shatin.
D T
DT
Yew
C B
CB
Luo
D R
DR
Zheng
Y L
YL
Guan
Y Q
YQ
Lin
W Z
WZ
Chen
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