汗腺发生过程中细胞外基质成分的组织化学变化

由于汗腺组织的毁损,大面积深度烧伤后创面修复均无排汗功能.表皮干细胞是皮肤及其附属器发生、修复、改建的关键性源泉[1].因此,我们设想模拟汗腺的发生,通过调控表皮干细胞的分化方向而重建汗腺,可能是重建汗腺的唯一途径.细胞外基质作为一功能活性区域,与细胞的分化紧密相关[2].我们通过汗腺发生过程中几种主要细胞外基质变化规律的观察,试图探明汗腺发生与细胞外基质间的最佳相关性,为诱导表皮干细胞定向分化为汗腺细胞提供依据.     

冻存对人脐血间充质干细胞生物学特性的影响

目的观察冻存复苏对人脐血（human umbili calcord blood）间充质干细胞（mesenchymal stem cells，MSCs）生物学特性的影响。方法体外分离、培养人脐血MSCs，传代后，将第3代的MSCs加入含10％二甲基亚砜（DMSO）和90％胎牛血清的细胞冻存液中，-196℃液氮保存4周，观察比较冻存前及冻存复苏后MSCs的形态、增殖及多向分化能力。结果冻存前及冻存复苏后，MSCs形态无明显差别，均呈典型的梭形，MSCs贴壁生长；MSCs生长曲线相似，冻存复苏后的细胞生长曲线略有下降，但差异无统计学意义（P〉0．05）；MSCs经脂肪诱导液诱导2周后，细胞浆中出现脂肪细胞所特有的脂肪滴，经0．5％油红0染色，脂肪滴染为红色，说明MSCs有向脂肪细胞分化的能力；Mscs经成骨诱导液诱导4周后，VonKossa染色可见黑色的矿化结节沉积，钙结节的形成为成骨细胞特有，说明Mscs有向成骨细胞分化的能力。提示冻存复苏后Mscs经诱导仍然可以向脂肪细胞和成骨细胞分化，与冻存前无明显差异。结论人脐血MSCs经冻存复苏后，其生物学特性可获良好保持。     

骨髓基质干细胞-80℃保存的初步研究

目的:探索适合于人骨髓基质干细胞-80℃冷冻保存的条件和方法。方法:体外分离培养人骨髓基质干细胞,以含不同浓度二甲亚砜的冻存液和不同细胞浓度-80℃深低温保存。3个月后复苏接种培养,观察细胞形态、存活率和贴壁率;通过3H-胸腺嘧啶脱氧核苷(3H-TdR)掺入实验比较细胞分裂增殖能力;3H-脯氨酸(3H-Proline)掺入实验检测胶原合成能力;RT-PCR法检测Ⅰ型胶原和骨钙素mRNA表达。结果:不同二甲亚砜浓度保存骨髓基质干细胞复苏后的细胞形态和功能有所不同,其中含5%二甲亚砜冻存液组保存效果最差,15%组最佳。15%二甲亚砜冻存液组复苏后骨髓基质干细胞的形态与未冻存组相似,存活率为(85%±3%),贴壁率为(81%±5%)。骨髓基质干细胞保持较强的分裂增殖和胶原合成能力,Ⅰ型胶原和骨钙素mRNA表达与5%或10%二甲亚砜冻存液组比较有统计学差异(P<0.05)。冻存骨髓基质干细胞浓度为(5～10)×106个/ml组复苏后细胞存活率明显优于(1～2.5)×106个/ml组。结论:含15%二甲亚砜的冻存液适合于骨髓基质干细胞长期保存,高浓度组骨髓基质干细胞冻存效果优于低浓度组。     

低温冻存对胚胎大鼠神经干细胞生物学特性的影响

目的 研究不同冻存液对胚胎大鼠神经干细胞的保护作用及低温冻存对神经干细胞增殖及分化潜能的影响。方法 分别应用冻存液Ⅰ和冻存液Ⅱ对源于胚胎大鼠的神经干细胞球进行冷冻,于复苏后进行传代培养,并鉴定其增殖和分化能力。结果 复苏后的神经干细胞可以多次传代,冻存神经干细胞的克隆增殖率为(36.80±3.81)％,未冻存者为(38.15±4.80)％,两者相比差异无显著性(P>0.05)。冻存液Ⅰ和冻存液Ⅱ保存的神经干细胞分化为神经元的比例分别为(7.61±0.74)％和(12.76±2.53)％(P>0.05);分化为少突胶质细胞的比例分别为(0.90±0.50)％和(2.18±0.33)％(P>0.05);分化为星形细胞的比例为(47.67±2.10)％和(35.38±3.14)％(P<0.05)。结论 冻存的胚胎大鼠神经干细胞复苏后仍具有活跃的增殖和分化潜能,含10％血清的冻存液可以促使神经干细胞向星形细胞方向转化。     

人羊水来源间充质干细胞冻存后生物学特征研究

目的体外分离培养人羊水间充质干细胞(human amniotic fluid-derived mesenchymal stem cells,HAFMSCs),观察低温冻存复苏后HAFMSCs生物学特征,为进一步研究奠定理论基础。方法取12份自愿捐赠的孕16～20周羊水标本,采用改良两步法分离培养HAFMSCs,用含量不同的FBS、DMSO冻存液冻存细胞,液氮冻存12周后42℃水浴复苏,锥虫蓝染色检测细胞存活率,MTT法检测细胞增殖速度并绘制生长曲线,流式细胞仪检测冻存复苏后HAFMSCs表型。对冻存复苏后的HAFMSCs进行成脂、成骨诱导分化培养,并分别采用油红O、von Kossa染色进行鉴定;实时荧光定量PCR分析细胞冻存前后Oct-4、Nanog mRNA表达差异。结果细胞冻存12周后,不同的冻存方案对细胞存活率影响有差异,优化的冻存方案为DMEM/FBS/DMSO=50%/40%/10%。冻存复苏后的HAFMSCs呈漩涡状排列,生长曲线呈S形,与冻存前细胞生长曲线相似。流式细胞仪检测示冻存复苏后细胞的MSCs表型CD29、CD44、CD73、CD90为阳性,造血干细胞表型CD34、CD45为阴性。成脂、成骨诱导21 d,油红O、von Kossa染色均呈阳性。实时荧光定量PCR检测示冻存前后Oct-4、Nanog mRNA表达水平差异无统计学意义(P>0.05)。结论 HAFMSCs具有体外增殖快、分化能力强的优势;并可耐受短期冻存,复苏后细胞存活率高,生物学特征及分化潜能未发生明显变化,冻存液DMEM/FBS/DMSO=50%/40%/10%是较好冻存方案。     

汗腺发生过程细胞外基质成分的免疫组织化学变化

由于汗腺组织的毁损 ,大面积深度烧伤后创面修复均无排汗功能。表皮干细胞是皮肤及其附属器发生、修复、改建的关键性源泉[1] 。因此 ,我们设想模拟汗腺的发生 ,通过调控表皮干细胞的分化方向而重建汗腺 ,可能是重建汗腺的唯一途径。细胞外基质作为一功能活性区域 ,与细胞的分化紧密相关[2 ] 。我们通过汗腺发生过程中几种主要细胞外基质变化规律的观察 ,试图探明汗腺发生与细胞外基质间的最佳相关性 ,为诱导表皮干细胞定向分化为汗腺细胞提供依据。一、材料和方法取胎龄 11～ 3 1周流产胎儿背部皮肤 2 0份 ,均为因车祸及其他外伤等原因导致…     

人胚胎期表皮干细胞与汗腺发生过程关系的研究

目的探讨表皮干细胞与胚胎期汗腺发生过程中的相关性,为诱导表皮干细胞向汗腺细胞定向分化奠定基础.方法分别取13～31周胚龄人胎儿背部全层皮肤,行常规组织学观察,并以免疫组织化学染色法(SP法),动态观察汗腺原基细胞、汗腺胚芽细胞及汗腺细胞对β1整合素与细胞角蛋白-19(K19)的表达特征.以细胞角蛋白-8(K8)免疫组化染色阳性为汗腺发生及成熟的鉴定标准.结果不仅汗腺原基细胞、汗腺胚芽细胞表达β1整合素与K19,成熟的汗腺细胞亦有表达,并持续存在于汗腺发生全过程.K8始于14～16周在汗腺芽细胞内表达,并持续存在.结论汗腺于胚龄14～16周开始发生,至第24周基本成熟.胚胎期汗腺发生过程中,表皮干细胞是汗腺发生的源泉.     

人工诱导获得汗腺上皮样细胞的研究进展

皮肤作为人体最大的器官,在维持体温平衡方面具有重要作用。而这一作用的实现,主要依赖汗腺的分泌排泄功能。在严重烧伤的患者中,汗腺组织常常受到严重破坏,失去其原有的功能,导致体温失调。因此,修复、再生汗腺组织成为亟待解决的重点问题。国内外学者已将多种干细胞诱导分化为具有一定分泌排泄功能的汗腺上皮样细胞。但在目前研究中,仍存在转化时间较长、转化率较低等难题。通过回顾各类干细胞分化为汗腺上皮样细胞的诱导因素、实验方法及条件,可为汗腺再生修复的研究提供参考。     

冻存复苏人脐带间充质干细胞体外扩增和向脂肪细胞分化的研究

目的：分离培养人脐带间充质干细胞（human Umbilical Cord Mesenchymal Stem Cells hUCMSCs）,观察其冻存复苏后向脂肪细胞定向分化的能力。方法：将剔除动静脉的新鲜人脐带组织切成小块培养,得到贴壁细胞,观察细胞生长及检测其表面抗原。将第1代的hUCMSCs采用梯度冷冻技术冻存5个月,复苏后培养至第12代时,加入成脂诱导剂培养。当诱导至21天时行油红O染色,7天及14天时用RT—PCR技术分别检测成脂转化基因过氧化物酶增殖剂受体（PPAR γ-2）和脂蛋白酯酶（LPL）。结果：组织块培养法收获的单个核细胞培养传代后,能获得均一贴壁的间充质干细胞,hUCMSCs冻存复苏后,活细胞约为86％,流式细胞仪分析这些细胞表达CDI3、CD44和CD71等MSCs标志物,不表达CD14、CD34和HLA—DR表面抗原。复苏细胞在成脂诱导剂的作用下,细胞中有脂滴产生,通过油红0染色显示细胞核周围有脂滴聚集,通过RT—PCR检测有LPL及PPARγ2 mRNA的表达。结论：采用组织块贴壁培养法分离获得的人脐带间充质干细胞可冷冻保存。复苏后培养至第12代仍具有向脂肪细胞分化的潜能,可作为脂肪组织工程种子细胞来源。     

脐带间充质干细胞向汗腺样细胞分化后的表型变化

目的：比较人脐带间充质干细胞（hUC-MSCs）向汗腺样细胞诱导前后表型特征的变化.方法：对hUC-MSCs进行分离、培养、鉴定,通过显微镜观察、免疫细胞化学、流式细胞术等方法比较hUC-MSCs经汗腺分化诱导培养液培养前后细胞形态变化及癌胚抗原（CEA）、角蛋白7（CK7）、CK8、CK14、CK18、CK19表达的差异.结果：hUC-MSCs向汗腺样细胞诱导前呈梭形,呈成纤维细胞样;流式细胞仪检测发现CD29、CD90表达阳性;而CD34、CEA、CK14、CK19表达阴性.经汗腺诱导培养基诱导后hUC-MSCs分化为外形肥大、不规则、类似铺路石样的细胞,聚集性增殖;免疫细胞化学检测显示CK7、CK8、CK18抗原表达阳性;流式细胞仪检测结果显示CEA、CK14、CK19的阳性表达率分别为77.98%,48.47%,20.85%.结论：hUC-MSCs经过汗腺分化诱导培养基培养后能够分化为表达汗腺细胞标记物抗原的汗腺样细胞.     

体外人骨髓间充质干细胞向汗腺细胞表型转化的实验研究

目的:研究骨髓间充质干细胞(MSCs)向汗腺细胞分化的可行性.方法:体外分别分离培养、扩增并鉴定MSCs和汗腺细胞,将汗腺细胞置于47℃环境中1 h建立汗腺细胞体外休克模型,继续孵育3～5 d,收集上清液作为条件培养基对MSCs分化诱导,应用免疫组织化学和流式细胞仪法检测对比共培养10 d后MSCs细胞表型的改变.结果...     

复合汗腺的组织工程三维皮肤模型的构建

目的：运用组织工程化方法在体外建立复合汗腺的三维皮肤模型,阐明汗腺体外再生的可行性,并为初步建立含有汗腺的仿生化功能性组织工程皮肤奠定实验基础。方法：分离培养人表皮细胞、成纤维细胞和汗腺细胞,将表皮细胞与汗腺细胞按1：1的比例共培养,在培养体系中分别加入含表皮细胞生长因子（EGF）的微球,噻唑蓝（MTT）法观察细胞增殖情况,并与培养时直接加入EGF及不加EGF的对照组进行比较。将共培养的细胞接种于复合成纤维细胞的胶原基质并通过三维培养方式构建组织工程皮肤模型,在模型中加入复合EGF的微球释放载体促进汗腺再生和上皮化进程,HE染色和免疫组织化学方法检测所构建组织工程皮肤以及体外再生汗腺的结构,并与模型中直接加入EGF和未加EGF的对照组进行比较。结果：MTT检测结果显示,与两对照组相比较,通过共培养方式获得的表皮与汗腺细胞团在复合EGF微球作用下生长良好,有明显增殖作用;组织学观察结果显示所构建组织工程皮肤模型具有和正常皮肤相似的结构,并在真皮浅层形成了类似汗腺结构的细胞密集区域,存在大量汗腺特异性标志——角蛋白19（CK19）和癌胚抗原（CEA）阳性的细胞,这种现象在单纯EGF组仅有微弱表现,在空白对照组则无此现象出现。结论：构建具有汗腺结构的体外皮肤模型具有可行性,这为汗腺再生和功能性组织工程皮肤的研究开创了新的途径。     

Regeneration of functional sweat gland-like structures by transplanted differentiated bone marrow mesenchymal stem cells

Regeneration of sweat glands after deep burns has been an unsolved problem. Owing to lack of perspiration, survivors of an extensive deep burn injury are leading a miserable life in sultry months. It was our contemplation to solve this problem by inducing bone marrow mesenchymal stem cells (MSCs) to acquire the phenotype of sweat gland cells in vitro. Then these cells were transplanted into fresh skin wounds resulting from excision of anhydrotic scars after healing of deep burn injury in five patients. Two to 12 months after the procedure, it was proved that there was recovery of perspiration function in all the MSCs' transplanted areas, as evidenced by positive iodine–starch perspiration test. Histological and biochemical observation confirmed the involvement of MSCs transformed sweat gland cells in the recovery of functional sweat glands, and the components of sweat collected from these areas were similar to that collected from normal skin. This is the first report of successful transplantation of MSCs in regenerating functional sweat glands, which may help solve the problem of depletion of sweat glands in patients surviving extensive deep burns in the future.     

人骨髓间充质干细胞向汗腺样细胞诱导分化的研究

目的：观察体外热休克汗腺细胞（SGCs）和人骨髓间充质干细胞（BM-MSCs）共培养体系中 BM-MSCs的形态和表型变化,为进一步表观遗传学表达谱的检测及汗腺诱导关键转录因子的研究提供实验基础。方法：体外分离、培养、扩增人BM-MSCs和 SGCs,成骨和成脂诱导分化以鉴定BM-MSCs 的分化功能。在 Tran-swell间接共培养体系中,培养的BM-MSCs和经47℃高温处理造成热休克的 SGCs 在 Transwell 板中间接共培养;在Transwell＋诱导因子共培养体系中,上室的BM-MSCs培养基中添加了汗腺诱导因子（无汗性外胚叶发育不良蛋白、重组人表皮生长因子和胰岛素-转铁蛋白-亚硒酸钠）。监测共培养过程中BM-MSCs的细胞形态变化,免疫荧光法检测诱导后BM-MSCs的表型改变。结果：经与热休克 SGCs 共培养诱导10 d后,部分 BM-MSCs 有由长梭形变为扁平状多边形的趋势,且局部细胞间连接紧密成片。BM-MSCs 诱导前不表达 CEA 和 CK19;BM-MSCs诱导后,Transwell间接共培养体系部分细胞 CEA 和 CK19表达阳性,Transwell＋诱导因子共培养体系CEA和CK19阳性细胞数明显多于 Transwell 间接共培养体系。结论：热休克汗腺细胞与 BM-MSCs 在 Tran-swell间接培养以及相关汗腺诱导因子的共培养体系下,BM-MSCs呈现向 SGCs诱导分化趋势。     

Epidermal stem cells are the source of sweat glands in human fetal skin: Evidence of synergetic development of stem cells, sweat glands, growth factors, and matrix metalloproteinases

The development of sweat glands is a complex biological process, and the extent of cellular trafficking between epidermal stem cells and the development of sweat glands is uncertain. Therefore, we studied the synergetic development effects of stem cells, sweat glands, growth factors, and matrix metalloproteinases (MMPs) in human skin. Human fetal skin was obtained from spontaneously aborted fetuses at 11-31 weeks of gestation. Paraffin sections were cut and stained with hematoxylin and eosin or immunostained with antibodies against beta(1) integrin, keratin (K)-19 and K7, MMP-2 and -7, and epidermal growth factor. In situ hybridization was used along with semiquantitative analysis of the positive expression of these proteins to analyze for mRNA expression of MMP-2 and -7. Histological studies revealed the fetal epidermis began to form a primary epidermal ridge at gestational age 13-14 weeks and these primordial basal cells became tightly packed to take the form of multiple hillocks between 14 and 16 weeks. Furthermore, these cells gave rise to chord-like columnar buds in the embryonic epidermis, and these buds gradually migrated downward into the dermis to form juvenile sweat glands at 18-20 weeks. Mature sweat glands were found in the fetal epidermis at the end of 24 weeks. beta(1) integrin and K19 immunoreactivities were first detected in those cells that gathered together to form primary epidermal ridges, including sweat gland cords, buds, and immature sweat gland cells. The positive immunostaining for K7 appeared in early sweat gland buds at 14-16 weeks, and from then on K7 was concentrated in developing sweat gland cords or cells. At 14-16 weeks, positive epidermal growth factor, MMP-2, and MMP-7 expression was first observed weakly in developing sweat gland buds. The immunoreactivity of these proteins was then gradually increased in the developing sweat gland buds and extracellular stroma from 14 to 20 weeks. The intensity of the positive signal peaked at 20-22 weeks of gestational age. After that, the intensity of immunostaining for MMP-2 and MMP-7 proteins was gradually weakened. However, the expression of epidermal growth factor did not show an apparent decrease. These results suggest that epidermal stem cells are the source of sweat glands. Epidermal growth factor is one of the main inducers in the development and maturity of sweat gland buds or cells and the local activated MMPs may play an important role in cleaving the major matrix components in the basement membrane.     

胰酶-EDTA差速消化法纯化原代培养的汗腺细胞

目的：探讨胰酶-EDTA差速消化法纯化原代培养的汗腺细胞的效果.方法：取新鲜的腹部手术患者腹部皮肤,D-Hanks液浸洗去除皮肤中的血液,剪成1 mm×1 mm大小的皮粒,将剪碎的皮粒放入装有5 ml （2 mg/ml） 的Ⅱ型胶原酶的培养皿中,置于37 ℃、5%CO2孵箱中消化8-12 h,倒置相差显微镜直视下吸取游离的汗腺,用汗腺培养基培养5-7 d,观察细胞形态和生长状况,加入胰酶-EDTA混合溶液2 ml（胰蛋白酶0.25,EDTA 0.53 mol/L）消化3 min,成纤维细胞收缩变圆后立即加入胎牛血清5 ml终止消化,吸弃消化液,D-Hanks冲洗2~3次,加入5 ml含10%胎牛血清DMEM培养液继续培养.镜下观察成纤维细胞去除效果,并对纯化后的细胞进行免疫细胞化学鉴定.结果：汗腺分离培养5-7 d后,汗腺细胞呈铺路石样生长,并且汗腺细胞周围生长有大量的成纤维细胞;用胰酶-EDTA消化3 min后,细胞计数显示约有95%以上的成纤维细胞被去除;免疫细胞化学鉴定结果显示纯化后的细胞CEA和CK8染色阳性,而波形蛋白和成纤维细胞特异性蛋白染色阴性.结论：胰酶-EDTA差速消化法能够简单、快速、高效地纯化汗腺细胞.     

The interaction between epidermal growth factor (EGF) and matrix metalloproteinase induces the development of sweat glands in human fetal skin

Objective:The development of sweat glands is a very complicated biological process involving many factors. In this study, we explore the inter-relationship between epidermal growth factor (EGF),matrix metalloproteinases (MMP-2,MMP-7) and development of sweat glands in human embryos. Furthermore, we hope to elucidate the mechanism(s) underlying the induction of epidermal stem cells into sweat gland cells. Methods:Skin biospies of human embryos obtained from spontaneous abortions at different gestational ages from 11 to 31 weeks were used in this study. The dynamical expression of EGF, MMP-2, MMP-7 and keratin-7 (K7) in developing sweat gland cells or extracellular stroma surrounding the sweat gland cells were examined with S-P immunohistochemical methods.The localization of the cellular sources of MMP-2 and MMP 7 was examined with in situ hybridization. Results:At 14-20 wk of gestation, a gradual increase in EGF immunoreactivity was observed not only in developing sweat gland buds but also in extracellular stroma surrounding the buds,and the expression intensity peaked at 20-22 wk of gesta- tional age. All mRNA-positive buds or cells in developing sweat glands contained corresponding immunoreactive proteins. Positive immunostaining for K7 appeared in early sweat gland buds at 14-16wk of gestation, and from then on, K7 was concentrated in developing sweat gland cords or cells. Conclusions: The morphogenesis of sweat gland in human fetal skin begins at 14-16wk of gestational age, and essentially completes by 24wk. There is a close relationship among EGF,extracellular matrix remodeling and morphogenesis of sweat glands, and EGF is one of the inducers in the development and maturity of sweat gland buds or cells.     

The interaction between epidermal growth factor and matrix metalloproteinases induces the development of sweat glands in human fetal skin

BACKGROUND: The development of sweat glands is a very complicated biological process involving many factors. In this study, we explore the interrelationship among epidermal growth factor (EGF), matrix metalloproteinase 2 (MMP-2), matrix metalloproteinase 7 (MMP-7), and the development of sweat glands in human embryos. Furthermore, we hope to elucidate the mechanism(s) underlying the induction of epidermal stem cells into sweat gland cells. MATERIALS AND METHODS: Skin biopsies of human embryos obtained from spontaneous abortions at different gestational ages from 11 to 31 weeks were used in this study. The dynamic expression of EGF, MMP-2, MMP-7, and keratin-7 (K7) in developing sweat gland cells or extracellular stroma surrounding the sweat gland cells was examined with SP immunohistochemical methods. The localization of the cellular sources of MMP-2 and MMP-7 was examined with in situ hybridization. RESULTS: At 14-20 weeks of gestation, a gradual increase in EGF immunoreactivity was observed not only in developing sweat gland buds but also in extracellular stroma surrounding the buds, and the expression intensity of EGF peaked at 20-22 weeks of gestational age. All mRNA-positive buds or cells in developing sweat glands contained corresponding immunoreactive proteins. Positive immunostaining for K7 appeared in early sweat gland buds at 14-16 weeks of gestation, and from then on, the positive signal of K7 was concentrated in developing sweat gland cords or cells. CONCLUSIONS: The morphogenesis of sweat glands in human fetal skin begins at 14-16 weeks of gestational age, and is essentially complete by 24 weeks. There is a close relationship among EGF, extracellular matrix remodeling, and morphogenesis of the sweat glands. EGF is one of the inducers in the development and maturity of sweat gland buds or cells.     

人胚胎期表皮干细胞与汗腺发生过程关系的研究

目的　观察表皮干细胞与胚胎期汗腺发生过程的关系 ,为诱导表皮干细胞向汗腺细胞定向分化奠定基础。　方法　分别取 13～ 3 1周胎龄人胎儿背部全层皮肤 ,采用常规组织学、免疫组织化学染色法 (SP法 ) ,动态观察汗腺原基细胞、汗腺胚芽细胞及汗腺细胞中 β1整合素与细胞角蛋白 19(K19)的表达特征。以细胞角蛋白 8(K8)免疫组化染色阳性为汗腺发生及成熟的鉴定标准。　结果　组织学观察显示 ,胎龄 16周的皮肤 ,初级表皮嵴基底层细胞呈灶性聚集 ,形成小丘状 ,继而形成圆柱状细胞索向深层切入 ;至胎龄第 2 4周时 ,细胞索末端部分形成蟠状 ,表现为成熟汗腺特征。不仅汗腺原基细胞、汗腺胚芽细胞表达 β1整合素与K19,成熟的汗腺细胞亦有表达 ,并持续存在于汗腺发生全过程。K8始于 14～ 16周 ,在汗腺胚芽细胞内表达并持续存在。　结论　汗腺于胎龄 14～ 16周开始发生 ,至第 2 4周基本成熟。胚胎期汗腺发生过程中 ,表皮干细胞是汗腺发生的源泉