转移生长因子β1对体外培养破骨细胞功能影响的实验研究

目的探讨转移生长因子β1(TGF-β1)对体外培养破骨细胞功能影响的机制.方法酶动力学法测定培养基中酸性磷酸酶和抗酒石酸酸性磷酸酶活性;共聚焦激光扫描显微镜观察体外培养破骨细胞内氢离子随TGF-β1浓度的变化情况;Leica Quantimet 500图像分析系统对骨吸收陷窝进行图像分析;扫描电镜观察骨吸收陷窝变化.结果随着TGF-β1浓度的升高,处理组与对照组ACP和TRAP的活性分别从(1.71±0.33U)/L和(1.41±0.29)U/L降低到(1.32±0.21)U/L和(1.01±0.11)U/L(均为P＜0.01),骨吸收陷窝的数目与面积从(16.67±1.35)个/片和(582.24±178.68)μm2减少到(13.29±1.47)个/片与(442.38±148.27)μm2,处理组与对照组比较差异具有显著性(P＜0.01).破骨细胞相对荧光值无显著性差异,表明TGF-β1对体外培养破骨细胞分泌H+无明显影响.结论TGF-β1虽然不能抑制氢离子释放,但能通过改变酸性磷酸酶和抗酒石酸酸性磷酸酶活性,进而直接抑制体外培养破骨细胞的骨吸收功能.     

血小板衍生生长因子-AA对破骨细胞功能的影响

目的　研究血小板衍生生长因子 (PDGF) AA对破骨细胞功能的影响。　方法　利用免疫电镜技术证明PDGF α受体在破骨细胞膜得以表达 ;酶动力学法测定培养基中酸性磷酸酶与抗酒石酸酸性磷酸酶活性 ;通过荧光探针在共聚焦显微镜下观察破骨细胞内氢离子随PDGF AA浓度的变化情况 ;利用甲苯胺蓝对骨吸收陷窝染色并在图像分析仪下测定其面积和数目。　结果　破骨细胞膜有胶体金颗粒沉着 ,抗酒石酸酸性磷酸酶的活性无显著变化 (P >0 0 5 ) ,细胞内氢离子显著增加 ,但PDGF AA不能促进其释放 ;骨吸收陷窝的面积与数目均无显著变化。　结论　PDGF AA虽然能够促进氢离子在细胞内产量增加 ,但由于不能显著改变抗酒石酸酸性磷酸酶活性 ,因而不能直接促进破骨细胞的骨吸收功能。     

骨水泥颗粒促进肿瘤坏死因子α诱导的破骨细胞形成及其骨吸收作用

目的:验证骨水泥颗粒对肿瘤坏死因子α(TNFα)诱导的破骨细胞形成及其生物学活性的影响。方法:体外培养外周血单核细胞,对照组加入TNFα和白细胞介素-1α(IL-1α)及巨噬细胞克隆集落刺激因子(M-CSF),实验组并分别加入含有或不含有硫酸钙的骨水泥(PMMA±BaSO4)颗粒。对培养终末细胞作组织化学染色检测破骨细胞标志物抗酒石酸酸性磷酸酶(TRAP)的表达,并以象牙磨片上虫蚀样骨吸收陷窝的形成为指标检测破骨细胞的生物学活性;并比较各实验组中TRAP阳性多核细胞(multinucleatedcells,MNCs)及虫蚀样骨吸收陷窝形成时间的早晚。结果:各组TRAP阳性MNCs的数量无明显差异;PMMA±BaSO4组象牙磨片上骨吸收陷窝的面积均较对照组大,差异具有显著性(P<0.01);并且PMMA±BaSO4组TRAP阳性的MNCs及虫蚀样骨吸收陷窝的形成均较对照组早。结论:PMMA±BaSO4颗粒能够促进TNFα诱导的破骨细胞分化提早发生并促进其骨吸收活性。     

体外研究橙皮苷抑制钛颗粒介导的破骨细胞分化

目的研究橙皮苷对钛颗粒介导前破骨细胞分化及成熟的影响。 方法骨髓巨噬细胞在巨噬细胞集落刺激因子(M-CSF)30 ng/ml及核因子κB受体活化因子配体(Rankl)50 ng/ml刺激下,诱导分化为破骨细胞。扫描电镜观察钛磨损颗粒形貌结构。对不同浓度下橙皮苷对巨噬细胞增殖的影响进行t检验分析得出最低有效浓度;对抗酒石酸酸性磷酸酶(TRAP)阳性细胞数及骨吸收陷窝面积判断橙皮苷对破骨细胞分化及成熟的影响。最后通过实时定量PCR(RT-PCR)验证橙皮苷对钛颗粒介导的破骨基因,包括活化T细胞核因子(NFATc1)、组织蛋白酶K (CTSK)、TRAP的影响。TRAP阳性细胞数及骨吸收陷窝面积、RT-PCR结果数据均采用t检验分析。 结果扫描电镜显示钛磨损颗粒大小在1～3 μm。CCK-8实验结果显示橙皮苷对巨噬细胞增殖有促进作用,浓度超过40 μmol/L后,会对巨噬细胞产生抑制作用(F＝40.1, P<0.01),所以选择40 μmol/L作为对巨噬细胞分化的影响。在抗酒石酸酸性磷酸酶染色中发现40 μmol/L的橙皮苷会明显抑制前破骨细胞的分化,TRAP阳性细胞数目及破骨细胞的面积明显减少(t＝5.5,P<0.05)。与对照组相比,扫描电镜观察钛颗粒介导骨吸收陷窝面积明显增多,但加入40 μmol/L的橙皮苷后,这种吸收效果或明显减少(t＝6.1,P<0.05)。最后,通过RT-PCR实验得出,40 μmol/L的橙皮苷会明显抑制破骨细胞分化相关NFATc1, CTSK,TRAP基因(t＝7.1、4.8、9.1,均为P<0.05)。 结论橙皮苷抑制钛颗粒介导的破骨细胞分化及成熟。     

阿司匹林对大鼠破骨细胞分化成熟和骨吸收活性的影响

目的 研究不同浓度阿司匹林对体外培养大鼠破骨细胞(Osteoclast,OC)分化成熟及骨吸收活性的影响.方法 建立由核激活因子受体配体(receptor activator of NF-κB ligand,RANKL)和巨噬细胞集落刺激因子(Macrophage colony stimulating factor,M-CSF)共同作用的大鼠破骨细胞骨髓诱导体系,将雌激素(10-6 mmol/L)和不同浓度的阿司匹林(0.25 mmol/L、0.5 mmol/L、1.0 mmol/L、1.5 mmol/L)分别作用于破骨细胞.诱导培养后分别对破骨细胞进行抗酒石酸酸性磷酸酶(The tartrate-resistant acid phosphatase,TRAP)染色,观察细胞形态,并计数破骨样细胞数量;将各组破骨细胞接种于骨磨片上,建立破骨细胞-骨磨片活性分析模型,于不同时间点对骨磨片进行光镜和扫描电镜观察,分析计算骨吸收陷窝面积.结果 与正常对照组相比,雌激素组破骨细胞数量和骨吸收陷窝面积低于正常对照组,差异有统计学意义(P＜0.05);且随着阿司匹林浓度的增加,阿司匹林组TRAP阳性多核破骨细胞数量、骨吸收陷窝面积逐渐减少直至消失,差异有统计学意义(P＜0.05).与雌激素组相比,低浓度阿司匹林组(0.25mmol/L)没有明显差异;但中、高浓度阿司匹林实验组(0.5mmol/L、1.0mmol/L、1.5mmol/L)破骨细胞数量和骨吸收陷窝面积减少,差异有统计学意义(P＜0.05).结论 阿司匹林对破骨细胞的分化成熟及骨吸收功能有抑制作用,且呈剂量依赖性,从而具有抗骨质疏松的作用.     

共育体系中成骨细胞和破骨细胞生物学特性观察

目的建立成骨细胞和破骨细胞的体外共育体系,观察在此体系中成骨细胞和破骨细胞生物学特性的变化,探讨成骨细胞和破骨细胞间的相互作用。方法取髂骨松质骨,Ⅱ型胶原酶消化,分次获得成骨细胞和破骨细胞。建立培养上清相通但二者互不接触的成骨细胞-破骨细胞共育模型。以细胞增殖(MTT法)、碱性磷酸酶(ALP)活性代表成骨细胞的成骨活性,以抗酒石酸酸性磷酸酶(TRAP)活性、骨吸收陷窝面积代表破骨细胞的破骨能力,检测共育对成骨细胞和破骨细胞生物学特性的影响。结果成骨细胞呈饱满的梭形,ALP染色阳性;破骨细胞呈多核,TRAP染色阳性,可以吸收骨质形成骨陷窝。当成骨细胞与破骨细胞共育后,其MTT法OD值(0.60±0.08)较单独培养时(0.36±0.03)明显提高(P=0.000);其ALP活性(23.37±2.48)u/mg较单独培养时(18.33±0.34)u/mg明显提高(P=0.000)。破骨细胞与成骨细胞共育后,形成骨吸收陷窝的平均面积犤(6.55±0.34)×10-2犦μm2较单独培养时犤(5.15±0.17)×10-2犦μm2明显增大(P=0.000)。结论共育体系中成骨细胞和破骨细胞的功能相互促进,为骨组织代谢的体外研究提供了可靠的模型。     

辛伐他汀抑制甲状旁腺素相关肽诱导的破骨细胞生成和功能

目的:探讨辛伐他汀对骨髓来源的破骨细胞形成和功能的影响。方法:取Balb/C雄性小鼠双侧股骨和胫骨的骨髓,以不含血清的α-MEM培养液洗涤并收集骨髓细胞,再将细胞重新悬浮于含100 m l/L胎牛血清的α-MEM培养液中,细胞计数后,配成1.5×109/L的细胞悬液,同时加入甲状旁腺素相关肽(PTHrP)和不同剂量的辛伐他汀(10-7、10-6、10-5mol/L)于24孔培养板进行培养,并设阳性对照(只加PTHrP)和阴性对照(PTHrP和辛伐他汀都不加)组,每组均有1孔放置骨磨片1片,培养6 d后;去除上清,抗酒石酸(TRAP)染色检测培养板底部破骨细胞形成;骨磨片用甲苯胺蓝染色,电镜检测骨磨片的吸收陷窝。结果:小鼠骨髓细胞在PTHrP的诱导下获得大量的TRAP染色阳性的破骨细胞,骨磨片有吸收陷窝形成;用辛伐他汀(10-7、10-6mol/L)和PTHrP共同培养下TRAP染色阳性的破骨细胞形成数量均明显减少(P<0.01),辛伐他汀在10-5mol/L时则无TRAP染色阳性的破骨细胞形成;辛伐他汀在10-7mol/L时骨磨片有吸收陷窝的形成但少于阳性对照组(P<0.01),在10-6、10-5mol/L时骨磨片则无吸收陷窝的形成。结论:辛伐他汀对小鼠骨髓来源的破骨细胞的形成有着明显的抑制作用,并且呈剂量依赖关系。     

活体外骨保护蛋白基因治疗磨屑诱导的骨溶解

本研究通过验证骨保护蛋白(OPG)逆转录病毒载体转导的成纤维细胞样滑膜细胞(FLS)表达OPG并抑制磨屑诱导破骨细胞生成的作用,探讨OPG基因治疗磨屑诱导的无菌性松动的可行性。首先建立了稳定转染细胞系。体外骨片吸收陷窝试验结果表明,FLS-OPG培养上清液抑制破骨细胞骨吸收功能,骨吸收陷窝面积为0.01(±0.01)mm~2,而FLS-LacZ培养上清液组骨吸收陷窝面积为3.53(±0.31)mm~2(P<0.001)。取健康雌性CBA×B6小鼠,麻醉下行颅骨表面正中矢状切口,暴露1×1cm~2颅骨表面,保留骨膜完整。根据植入材料不同,分5组:即30mg钛颗粒和10~(-7)FLS-OPG组、30mg钛颗粒和1~(-7)FLS-LacZ组、10~(-7)FLS-OPG组、10~(-7)FLS-LacZ组、单纯手术组(SHAM)。造模3天后,     

唑来膦酸钠在抑制钛颗粒诱导骨溶解中作用的体外实验研究

目的：研究唑来膦酸钠（ ZOL）对钛颗粒诱导的骨溶解的影响。方法分离6～8周C57BL/6J小鼠长骨中的前体破骨细胞（ OCP）并分为6组,A组：OCP＋细胞培养液,B组：OCP＋巨噬细胞集落刺激因子（M-CSF）＋NF-κB 受体活化因子配体（RANKL）＋细胞培养液,C组：OCP＋钛颗粒＋细胞培养液,D组：OCP＋上清液（钛颗粒刺激巨噬细胞24 h后上清液）＋细胞培养液,E组：OCP＋M-CSF＋RANKL＋ZOL＋细胞培养液,F组：OCP＋上清液＋ZOL＋细胞培养液。每组细胞分别接种在玻璃盖玻片、皮质骨磨片和含骨检测表面的96孔板上,10 d后检测玻璃盖玻片上细胞抗酒石酸磷酸酶（ TRAP）的表达及皮质骨磨片上骨吸收陷窝的形成,并以骨检测表面的骨吸收面积为指标比较各组破骨细胞的骨吸收活性。结果 B组、D组、E组和F组的OCP均能分化为能被TRAP染色成阳性的破骨细胞并形成骨吸收陷窝,其余组均未发现TRAP染色阳性的破骨细胞和骨陷窝。加入ZOL的F组骨吸收面积（5.54％±1.25％）较D组（10.34％±1.69％）明显减少,差异具有统计学意义（t＝5.61,P＜0.01）。结论在体外实验中钛颗粒并不能直接刺激前体破骨细胞向破骨细胞转化;唑来膦酸钠可以抑制钛颗粒诱导的骨溶解作用。     

重组人骨保护素与重组核因子κb活化因子受体蛋白对破骨前体细胞分化的影响

目的:对比重组人骨保护素(rhOPG-Fc)与重组核因子κb活化因子受体蛋白(rhRANK)对破骨前体细胞分化的影响.方法:采用成骨细胞与破骨前体细胞RAW264.7混合培养,在地塞米松、1,25 (OH) 2VitD3诱导下生成破骨细胞的方法.研究分3组:rhRANK组:10-5 g/L;rhOPG-Fc组:10-5 g/L;空白对照组.作用9d后观察破骨细胞数目和形态,抗酒石酸酸性磷酸酶(TRAP)染色阳性细胞个数,骨磨片吸收陷窝计数.结果:在空白对照组,小鼠成骨细胞与破骨前体细胞RAW264.7混合培养6d后,开始出现多核细胞,9d时可见大量成熟多核细胞,经TRAP染色证实为成熟破骨细胞,而rhRANK组及rhOPG-Fc组TRAP染色阳性多核细胞数较对照组均减少,特别是rhRANK组减少更明显.骨片吸收陷窝计数显示rhRANK组及rhOPG-Fc组较对照组也明显减少,而相对来说,rhRANK组较rhOPG-Fc组更少.结论:rhOPG-Fc与rhRANK均可以有效抑制破骨前体细胞分化成为成熟破骨细胞,且rhRANK较rhOPG-Fc抑制效果更明显.     

Polypeptide growth factors and the kidney: a developmental perspective

A variety of polypeptides with stimulatory or inhibitory effects on cell proliferation have been identified. In addition to stimulating or inhibiting the proliferation of cells and maintaining their viability, polypeptide growth factors play significant roles in embryogenesis and differentiation. The current review focuses on five specific polypeptide growth factor families (epidermal growth factor, insulin-like growth factors, transforming growth factors, platelet-derived growth factor, and fibroblast growth factors) and discusses their possible relationship to normal renal physiology, abnormal renal pathophysiology, and renal organogenesis. On the basis of current data, it is clear that polypeptide growth factors are multifunctional agents with important effects on renal function and renal organogenesis.     

Changes in gene expression of growth factors and their receptors during castration-induced involution and androgen-induced regrowth of rat prostates

To find candidates for the mediator of the growth-promoting action of androgen in rat prostates, the changes in the steady-state levels of mRNAs coding for several growth factors and their receptors were examined by Northern blot analysis during castration-induced involution, and subsequent regrowth induced by androgen in the ventral and dorsolateral lobes. The changes in the growth factor systems and a typical secretory protein in the ventral lobe were similar to, but more prominent than, those in the dorsolateral lobe, showing the higher androgen dependency of the ventral lobe. Among the growth factors and their receptors investigated, only epidermal growth factor (EGF) showed apparent positive androgen dependency: EGF mRNA content in the ventral lobe decreased to about 30% of the normal level within 24 hr after castration, and increased, attaining about 200–300% of the normal level 3–5 days after androgen administration to castrated rats. mRNAs coding for all other factors examined, i.e., transforming growth factor-α (TGF-α), EGF receptor, basic fibroblast growth factor (bFGF), keratinocyte growth factor (KGF), FGF receptor 1, TGF-β1, TGF-β type II receptor, hepatocyte growth factor (HGF), and c-MET/HGF receptor, increased after castration in greater or lesser degree, and after a brief pause or a decrease some of them increased again attaining a second peak 3–5 days after androgen replacement. The second increase was evident in TGF-α, EGF receptor, KGF, and c-MET mRNAs. These results indicate the possibility that multiple growth factor-receptor systems participate in the androgen-dependent regrowth of castrated rat prostates. © 1996 Wiley-Liss, Inc.     

Activity of Keratinocyte Growth Factor-Like Substance Extracted from Rabbit Liver on Renal Tubular Cell Growth during Compensatory Renal Hyperplasia

Background : In response to unilateral nephrectomy, the rabbit liver transiently produces 2 growth regulators for cultured renal cortical tubular cells: a tubular cell growth factor and a growth inhibitor. We report on the effects of the tubular cell growth factor on a variety of cell lines.
Methods : The tubular cell growth factor activity was partially purified from the rabbit liver by using gel filtration and ion-exchange chromatography. The activity was monitored by the incorporation of iododeoxyuridine into DNA of cultured cells. Expression of the fibroblast growth factor receptor-2 in the rabbit kidney was determined by the immunoblot analysis.
Results : This growth factor stimulated the DNA synthesis in LLC-PK, cells, LLC-RK, cells, and human keratinocytes. It did not affect the growth of BS-C-1 cells, MDCK cells, BALB/c 3T3 fibroblasts, or rat parenchymal hepatocytes. The additive effect of this factor on the DNA synthesis of cultured tubular cells maximally was stimulated by insulin-like growth factor-l, basic fibroblast growth factor, and epidermal growth factor, but was not stimulated by keratinocyte growth factor. The amount of this activity also increased in the liver after sham operation. In the days after surgery, expression of fibroblast growth factor receptor-2, which includes the keratinocyte growth factor receptor, was down-regulated in the kidneys of both uninephrectomized and sham-operated rabbits.
Conclusion : These findings indicate that tubular cell growth factor in the liver seems to be a keratinocyte growth factor, and acts in an endocrine manner in renal tubular hyperplasia.     

PDGF与IGF对骨形成的协同作用及机制

骨的形成、发生、发展是一个极其复杂的过程,在众多的影响因素中,生长因子的局部调节发挥着重要的作用[1].同时,在任何时候,骨细胞的微环境中都存在不止一种生长因子,骨的形成是在多种生长因子相互作用的网络调节下实现的.因此研究骨生长因子之间的相互作用,对进一步阐明骨形成、发生机理,筛选有协同作用的生长因子联合应用修复骨缺损,治疗骨组织疾病,具有重要的理论和实践意义.现就PDGF与IGF的协同作用作以下综述.……     

软骨生长因子对兔软骨细胞作用的实验研究

目的：探讨软骨生长因子（CDGF）对体外培养兔软骨细胞的作用。研究了CDGF,胰岛素样生长因子－I（IGF－I）及软骨细胞生长代谢三者之间的关系。方法：体外单层培养兔软骨细胞,取生长良好的第二代细胞实验,分别或共同加入不同浓度CDGF和IGF－I,利用氯胺T法和MTTI地分别观察比较细胞培养液中羟脯氨酸与能量的合成及细胞的增殖情况,结果：CDGF与IGF－I均能剂量依赖性的促进细胞外基质中羟脯氨酸的合成以及细胞的增殖与能量合成;对两种作用的最佳刺激浓度,CDGF分别为16ng/ml和32ng/ml,IGF-I为30ng/ml;二者联合应用能明显增强对软骨细胞作用。结论：CDGF可以刺激软骨细胞的增殖与胶原合成,并与IGF－I有协同作用。     

表皮细胞生长因子和碱性成纤维细胞生长因子在不同发育阶段大鼠皮肤表达特征的比较性研究

目的 研究表皮细胞生长因子（EGF）和碱性成纤维细胞生长因子（bFGF)在胚胎、新生及成年三个不同发育阶段大鼠皮肤的表达特征及其可能的生物学意义。方法 取胚胎、新生和成年大鼠皮肤,经4%多聚甲醛固定、包埋与切片后,用SP免疫组织化学法研究EGF和bFGF的定位与表达特征。结果 EGF的阳性表达可见于胚胎、新生及成年三个发育阶段大鼠皮肤,主要位于表皮棘细胞,真皮成纤维细胞、毛囊上皮细胞和血管内皮细胞胞浆,bFGF在新生和成年大鼠表皮及真皮呈强阳性表达,但在胎鼠皮肤则为弱阳性乃至阴性,结论 EGF在不同发育阶段大鼠皮肤呈强阳性表达,表明其对上皮的发生、表型维持以及损伤后的修复十分重要。而大鼠胚胎皮肤bFGF低表达或缺乏的结果表明它可能是动物胚胎创伤后无瘢痕愈合的原因之一。     

表皮细胞生长因子及其受体在胎儿和成人肠道组织中的表达特征

目的探讨表皮细胞生长因子(EGF)及其受体(EGFR)在不同发育阶段人小肠组织中的表达特征及其可能的生物学意义。方法24例被测标本中包括胎儿(胎龄13～31周)的小肠组织18例，成人(16～54岁)的小肠组织6例。用病理学技术和免疫组织化学方法确定EGF及EGFR两种蛋白在胎儿、成人小肠组织中的定位以及表达量的变化规律．结果EGF及EGFR在不同胎龄的胎儿和成人小肠组织中均有阳性表达。随着胎儿生长发育，小肠组织中EGF和EGFR的蛋白含量逐渐增加，这一变化趋势一直保持到成人小肠组织中。其中EGF主要存在于小肠黏膜上皮细胞、黏膜下层的血管内皮细胞内和浆膜上皮细胞的胞浆和胞外基质中，EGFR则分布于这些细胞的细胞膜上。结论EGF及EGFR在不同发育阶段的小肠组织中呈阳性表达，这种细胞因子可能以自分泌或旁分泌方式调节人肠道的生长发育、结构和功能的维持，并可能在小肠损伤后的修复中起重要作用。     

Polypeptide growth factors in metanephric growth and segmental nephron differentiation

Although the developing nephron expresses receptors for various polypeptide growth factors, the specific roles of such factors in renal organogenesis are unknown. Therefore, the effects of epidermal growth factor (EGF) (8.2×10^–11 M-1.6×10^–8 M), multiplication stimulating activity (MSA) (6.6×10^–10 M-1.3×10^–8M) and transforming growth factor beta (TGF-) (1×10^–12 M-1×10^–9 M) on organotypic renal growth and segmental nephron differentiation were studied in a serum-free hormonesupplemented, murine metanephric organ culture system. Following culture in control or growth-factor-supplemented medium, explant growth was assessed, and explant growth and differentiation were determined morphometrically in four defined nephron segments which were identified morphologically or immunohistologically with segment-specific antibodies and/or lectins: glomeruli, proximal tubules, thick ascending limb-early distal tubules, and collecting tubules. Results showed that EGF increased overall renal growth and specific differentiation of distal elements, but retarded differentiation of glomeruli and proximal tubules. EGF also induced hyperplastic cystic malformation in proximal tubules. MSA stimulated explant growth and promoted segmental differentiation of all tubular segments. TGF- globally retarded in vitro nephrogenesis. Such data demonstrate that polypeptide growth factors have multiple and often disparate effects on overall renal growth in relation to differentiation of discrete nephron segments and provide insight into the factors which may regulate normal and abnormal renal embryogenesis.     

Clinical significance of EGF and EGFR expression changes in cryptorchid boys

Aim: To explore the changes of epidermal growth factor (EGF) and epidermal growth factor receptor (EGFR) expressions in cryptorchid children and their clinical significance. Methods: The level of serum EGF was measured by radioimmunoassay (RIA) and the expression of EGFR by immunohistochemistry. Results: (1) The level of serum EGF was significantly lower in cryptorchid children than in normal subjects at age group of 59 years (P<0.01) and 10-14 years (P<0.01), (2) The level of EGF was significantly lower in boys with impalpable testis than in those with extracanalicular and intracanalicular testes (P<0.01), (3) The serum EGF level increased significantly 6 months after orchiopexy (P<0.05), (4) The EGFR expression in testicular Leydig's cells was lower in 2-4 year-old boys than in those over 5 years (P<0.05) and (5) the EGFR expression was less positive in the impalpable group and the intracanalicular group than that of the extracanalicular group (P<0.01). Conclusion: The EGF and EGFR expr essions may co