人胚胎发育中p75 NTR免疫阳性肠神经元的时空分布研究

Temperospatial expression patterns of p75NTR in enteric neurons during embryogenesis

目的通过定位和半定量分析胚胎各期肠神经嵴干细胞特异性标记p75NTR(p75)的表达水平,了解p75免疫阳性肠神经元在人类胚胎整个发育过程中的空间和时间的分布变化,为进一步阐明先天性巨结肠的发病机制和初步确定神经干细胞移植治疗先天性巨结肠获取供体细胞来源部位提供研究基础。方法流产胎儿标本20例,根据胎龄分为早期组(3个月,n=6)和中晚期组(4～9个月,n=14)。全消化道从口端到尾端分为3组:前肠、中肠和后肠。链霉亲合素-过氧化酶法免疫组织化学染色分析各期各部位p75NTR的表达水平。结果胚胎发育各期(3～9个月)全消化道各部位肌间丛和黏膜下丛均可见肠神经元胞浆和神经纤维内有p75阳性表达,胶质细胞和平滑肌细胞未见有p75阳性表达。肌间丛强阳性表达率早期为44.4%(8/18),中晚期为57.1%(24/42),均高于黏膜下丛相应各期(11.1%,19.0%,P<0.05)。中晚期肌间丛强阳性表达率在前肠(36/42,85.7%)高于中肠(18/42,42.9%)和后肠(15/42,35.7%)(P<0.05)。结论p75阳性肠神经嵴干细胞可能稳定地存在于各期前肠、中肠和后肠的肌间丛和黏膜下丛,而且肌间丛p75NTR表达水平高于黏膜下丛。而在胚胎发育中晚期,前肠肌间丛p75NTR表达水平高于中后肠肌间丛。

Objective To study the expression of p75NTR, a specific gut neural crest stem cell marker, in enteric neurons during human embryogenesis. Methods ‘Normal’ aborted human embryo specimens were collected （n = 20） and divided into two groups： early developmental （n = 6） and mid/ late developmental stages （n = 14） based on the gestational ages. The guts were further divided into foregut, midgut and hindgut. Expressions of p75NTR were analyzed with immunohistochemistry. Re- suits p75NTR was expressed in both the neuronal cytoplasm and nerve fibers in both myenteric and submucous plexuses along the complete length of gut through out the developmental stages （3- 9months）. P75NTR is absent in both glial and smooth muscle cells. The strong positive enteric neurons account for 44. 4% （8/18） at early stage and 57. 1% （24/42） at mid/late stage respectively in myenteric plexuses （PLA）, which were significantly higher than those in submucous plexus （PLM） at each stage （11.1%, 19. 0%, P〈0. 05）. Regarding mid/late-stage PLA, the strong positive rate in foregut （36/42, 85. 7%） is significantly higher than those in both midgut （18/42, 42. 9%） and hindgut （15/42, 35.7% ）（P〈0. 05）. Conclusions p75NTR positive gut neural crest stem cells are expressed within both myenteric and submucous plexuses in foregut, midgut and hindgut during embryogenesis. Meanwhile, the expression of p75NTR is stronger in myenteric plexuses than in that in submucous plexuses, stronger in foregut than in midgut and hindgut at told/late developmental stage.