人胎儿真皮乳头和皮纹发生的研究

本文用扫描电镜法研究了入胎儿的皮纹发生过程,包括初级真皮嵴、次级真皮嵴、真皮乳头和表皮隆线的发生。为研究人皮纹的发生和皮肤的异常提供了皮肤正常发育的形态学依据。共观察111例从第6周到第9个月胎儿的皮纹区皮肤,表明第3个月末胎儿开始形成初级真皮嵴,以后逐渐加深,至第16周嵴的顶端中央产生纵沟形成两条平行的次级真皮嵴;自19周后,次级真皮嵴局部隆起,由波浪形逐渐形成乳头。至30周乳头呈犬牙状。表皮隆线于第4—5月形成,随真皮乳头的增高而渐趋明显。至第6个月,全部皮纹图样已可辨认。本文还讨论了真皮乳头发生的过程。     

羧甲基壳聚糖促进小鼠皮肤毛囊再生修复的组织形态学研究

目的:观察羧甲基壳聚糖(CMC)促进小鼠皮肤毛囊再生修复的组织形态学结构变化,并与新生小鼠皮肤毛囊的组织形态学结构对比。方法:通过切除皮肤组织建立小鼠背部皮肤组织全层缺损模型,随机分为4组:CMC组、清得佳组、生理盐水组与空白对照组,除空白对照组外其余3组每天分别连续给药,第21天处死;为评估造模后小鼠皮肤毛囊组织的再生修复程度,另取新生小鼠36只,每日处死3只;应用Image J技术观察并测量各组小鼠皮肤组织创面修复率;HE染色后光镜下观察新生小鼠皮肤组织厚度、毛囊及"腺泡样"结构数量;对比分析各组小鼠模型第21天和新生小鼠皮肤毛囊的组织形态学结构。结果:第3天和17天各组小鼠模型皮肤创面再生修复率:CMC组为33.07±9.52%和96.75±2.11%,清得佳组为24.18±6.14%和92.22±0.62%,生理盐水组为21.06±11.59%和87.38±2.79%,空白对照组为8.66±2.27%和85.15±1.34%;采用线性模型重复度量方差分析法,对CMC组与清得佳组、生理盐水组和空白对照组小鼠皮肤创面第17天再生修复率比较存在显著性差异(F=11.970,17.666,8.828,P0.05)。新生小鼠皮肤厚度、毛囊及"腺泡样"结构数量随小鼠日龄增长而增加(r=0.983,0.922,P0.05)。与新生小鼠皮肤毛囊的组织形态学结构相比,第21天CMC组、清得佳组、生理盐水组及空白对照组小鼠模型皮肤组织再生修复程度分别相当于新生小鼠皮肤毛囊发育后期、中期、初期及瘢痕组织。结论:CMC具有促进皮肤毛囊组织形态学结构再生修复的重要作用。     

孕马血清促性腺激素对幼龄鼠卵巢和子宫发育的影响

目的探明孕马血清促性腺激素（PMSG）调控哺乳动物生殖生理机制。方法用4 IU PMSG分别处理出生第5天、第10天、第15天和第21天幼鼠,观察其对卵巢和子宫发育的影响。结果（1）PMSG处理后,出生第15天幼鼠的卵巢指数（33.08%）与对照组（27.16%）间差异显著（P〈0.05）;（2）PMSG处理后,第5天、10天和第15天幼鼠的初级卵泡和有腔卵泡相对数量与对照相比无差异,而21 d处理组次级卵泡相对数量显著增加;（3）虽然出生后10 d前的幼鼠子宫对PMSG的反应较弱,但是,PMSG对出生后15-21 d幼鼠子宫重量指数、子宫肌层和子宫内膜层厚度发育具有明显的促进作用,而对子宫腺体数量增加无影响。结论PMSG对幼鼠卵巢的发育无明显影响;PMSG对出生后第15天前后的子宫发挥作用,而且其作用随着出生日龄的增加而增强。     

SD大鼠皮肤组织病理学观察

目的观察不同日龄SD大鼠皮肤组织学结构。方法10％甲醛固定,行石蜡切片,HE染色。结果新生大鼠皮肤较薄,透明层缺乏,皮脂腺发育良好。6月龄时表皮、真皮和皮下组织明显增厚,毛囊增粗,生长旺盛,毛囊深入皮下脂肪层。24月龄时,大鼠皮脂腺及汗腺萎缩,表皮变薄,真皮成纤维细胞、血管数量减少,弹力纤维变细。结论不同日龄SD大鼠皮肤组织学结构有差异。     

小鼠卵巢几个重要发育事件的初步研究

选定多个阶段小鼠卵巢进行切片染色和生殖细胞计数统计等分析,以发现该阶段小鼠卵巢的发育特点。结果显示在胚胎发育第12.5 d的生殖嵴中,大部分的生殖细胞正进行有丝分裂增殖,并以生殖包囊的形式存在;在出生后第2 d的小鼠卵巢中,有大量紧密接触的原始卵泡,表明生殖包囊刚完成重组形成原始卵泡;在第5 d的小鼠卵巢中,原始卵泡仍占有大部分比例,但也有大量的初级卵泡处于发育之中;在出生后第10 d的卵巢中同时有原始卵泡、初级卵泡和次级卵泡的发育;老年小鼠(16个月大)卵巢中已基本没有卵母细胞。     

Hr突变体转基因小鼠的构建和表型分析

无毛基因（Hr）定位于8p12,在染色体上跨越14 kb,包含19个外显子。无毛基因的自发突变能引起人和动物毛发脱落及相关毛发疾病的产生。为深入研究Hr基因的功能,本文利用Gateway技术构建Hr表达载体,在该基因的3 427位引入点突变(G→A),通过显微注射建立转基因小鼠。采用PCR方法鉴定出阳性的转基因小鼠,确定首建鼠,通过与C57BL/6小鼠回交后互交数代建系。观察转基因小鼠毛发生长发育规律。结果表明,成功构建了pRP(Exp)-EF1A>mHairless mutant>IRES/EGFP真核表达载体,通过与野生型小鼠杂交获得阳性子代,进行同窝交配,第2代小鼠出生后14 d开始脱发,30 d左右脱落的毛发重新长出。取部分皮肤组织做石蜡切片,皮肤组织学观察发现,脱毛期无毛小鼠毛囊瓦解,真皮内形成大小不等的包囊,毛发重新生长时,真皮内见大量新生的毛囊。蛋白印迹实验表明,转基因小鼠脱发时HR蛋白表达量明显高于同龄阴性小鼠。本文成功建立稳定遗传的Hr突变的转基因小鼠品系,推测无毛基因突变引发转基因小鼠的脱发,为研究Hr基因的功能提供了良好的动物模型。     

氧氟沙星对小鼠生殖毒性和致畸性的研究

目的研究氧氟沙星对昆明系小鼠胚胎和胎鼠发育的影响,确定其是否存在生殖毒性和致畸性。方法①雄鼠分别灌服各剂量氧氟沙星,连续10d,末次给药24h后与母鼠合笼,在妊娠第三天取胚胎,记录各剂量组胚胎发育率。②孕鼠妊娠零天给药,分别经口灌服高、中、低剂量[36、72和360mg(kg.bw)]氧氟沙星溶液,连续给药3d,在妊娠第三天收集胚胎,记录胚胎发育率。③孕鼠妊娠零天给药,分别经口灌服各剂量氧氟沙星溶液,连续给药10d,在妊娠第16天取出胎鼠,记录胎鼠体重、胎盘重、活胎数、胎鼠外观畸形和内脏畸形等指标。结果给药组与对照组相比,雄鼠服用高剂量组360mg(kg.bw)氧氟沙星对着床前胚胎发育影响显著(P<0.05),而中等剂量和低剂量组对着床前胚胎发育的影响不显著(P>0.05)。雌鼠服用不同剂量氧氟沙星对着床前胚胎发育影响不显著(P>0.05)。氧氟沙星对受孕鼠的活胎数和吸收胎数均无明显影响,给药组的活鼠体重、胎盘重均未见明显差异(P>0.05);药物组和对照组均未出现外观畸形和内脏畸形,也不存在剂量和效应关系。结论孕鼠服用不同剂氧氟沙星对昆明系小鼠胚胎和胎鼠发育无明显的影响,表明氧氟沙星对雌性鼠不具有明显的生殖毒性和致畸性;但雄鼠服用高剂量氧氟沙星对着床前胚胎发育影响显著。     

小鼠睾丸表皮生长因子受体及增殖细胞核抗原表达的加龄变化研究

观察了表皮生长因子受体及增殖细胞核抗原在生后１天至生后１０月龄昆明种小鼠睾丸内的表达,结果表明：精原细胞及初级精线产细胞从生后第２周至生后４周龄ＤＮＡ复制旺盛,增殖细胞核抗原免疫反应阳性细胞面密度于生后１４天出现峰值。生长因子受体在间质细胞、精母细胞内均有表达。生后４周时,精母细胞表皮生长因子受体表达较强,便于表皮生长因子发挥调节细胞增殖、调亡的作用。     

Edar信号通路调控毛囊发育的研究进展

Edar信号通路最早发现于人少汗型外胚层发育不良综合征(hypohidrotic ectodermal dysplasia,HED)疾病患者,它是调控胚胎发育早期皮肤附属物——头发、指甲、牙齿、外分泌腺等的形态发生、发育过程的重要信号通路。与人类相同,小鼠皮肤内毛囊于胚胎期发生并发育成熟,出生后进入动态变化的毛囊周期性生长。小鼠模型的相关研究表明,Edar信号通路在早期初级毛囊的发生、成体毛囊周期性生长和被毛纤维直径等方面都发挥重要的调控作用。现综述Edar通路中重要信号分子的结构特点、转导途径及其在皮肤和毛囊早期形态发生中的作用;阐述Edar信号通路对毛囊生长周期的调控,对维持皮肤微环境稳态、促进皮肤损伤修复和表皮再生的作用,以及在临床治疗HED相关疾病方面的潜在应用前景。     

小鼠毛囊发育分子遗传学机制研究进展

毛囊作为皮肤的附属器官,具有不断进行组织再生的特点,是研究干细胞的一种理想模型。毛囊发育机制十分复杂,其形态发生与持续终生的再生循环过程涉及表皮(上皮)和真皮(间充质)之间的相互作用。现已有相关的小鼠遗传模型被用于研究毛囊发育及再生的分子机制。该综述介绍最新的小鼠遗传学研究,主要涉及在毛囊发育过程中分别来自表皮和真皮中关键信号分子的敲除或过表达,以描绘一个控制毛囊发育和周期性循环的信号网络,为深入立体地理解毛囊发育机制和临床毛发疾病发病机制提供理论依据。     

Embryonic dermal condensation and adult dermal papilla induce hair follicles in adult glabrous epidermis through different mechanisms

Hair induction in the adult glabrous epidermis by the embryonic dermis was compared with that by the adult dermis. Recombinant skin, composed of the adult sole epidermis and the embryonic dermis containing dermal condensations (DC), was transplanted onto the back of nude mice. The epidermis of transplants formed hairs. Histology on the induction process demonstrated the formation of placode-like tissues, indicating that the transplant produces hair follicles through a mechanism similar to that underlying hair follicle development in the embryonic skin. An isolated adult rat sole skin piece, inserted with either an aggregate of cultured dermal papilla (DP) cells or an intact DP between its epidermis and dermis, was similarly transplanted. The transplant produced hair follicles. Histology showed that the epidermis in both cases surrounded the aggregates of DP cells. The epidermis never formed placode-like tissues. Thus, it was concluded that the adult epidermal cells recapitulate the embryonic process of hair follicle development when exposed to DC, whereas they get directly into the anagen of the hair cycle when exposed to DP. The expression pattern of Edar and Shh genes, and P-cadherin protein during the hair follicle development in the two types of transplants supported the above conclusion.     

Notch1 is essential for postnatal hair follicle development and homeostasis

Notch genes encode evolutionarily conserved large, single transmembrane receptors, which regulate many cell fate decisions and differentiation processes during fetal and postnatal life. Multiple Notch receptors and ligands are expressed in both developing and adult epidermis and hair follicles. Proliferation and differentiation of these two ectodermal-derived structures have been proposed to be controlled in part by the Notch pathway. Whether Notch signaling is involved in postnatal hair homeostasis is currently unknown. Here, we investigate and compare the role of the Notch1 receptor during embryonic hair follicle development and postnatal hair homeostasis using Cre-loxP based tissue specific and inducible loss-of-function approaches. During embryonic development, tissue-specific ablation of Notch1 does not perturb formation and patterning of hair follicle placodes. However, Notch1 deficient hair follicles invaginate prematurely into the dermis. Embryonic as well as postnatal inactivation of Notch1 shortly after birth or in adult mice results in almost complete hair loss followed by cyst formation. The first hair cycle of Notch1 deficient mice is characterized by shortened anagen and a premature entry into catagen. These data show that Notch1 is essential for late stages of hair follicle development during embryogenesis as well as for post-natal hair follicle development and hair homeostasis.     

Dynamic regulation of retinoic acid-binding proteins in developing, adult and neoplastic skin reveals roles for beta-catenin and Notch signalling

Retinoic acid (RA) signalling is essential for epidermal differentiation; however, the mechanisms by which it acts are largely unexplored. Partitioning of RA between different nuclear receptors is regulated by RA-binding proteins. We show that cellular RA-binding proteins CRABP1 and CRABP2 and the fatty acid-binding protein FABP5 are dynamically expressed during skin development and in adult tissue. CRABP1 is expressed in embryonic dermis and in the stroma of skin tumours, but confined to the hair follicle dermal papilla in normal postnatal skin. CRABP2 and FABP5 are expressed in the differentiating cells of sebaceous gland, interfollicular epidermis and hair follicles, with FABP5 being a prominent marker of sebaceous glands and anagen follicle bulbs. All three proteins are upregulated in response to RA treatment or Notch activation and are negatively regulated by Wnt/β-catenin signalling. Ectopic follicles induced by β-catenin arise from areas of the sebaceous gland that have lost CRABP2 and FABP5; conversely, inhibition of hair follicle formation by N-terminally truncated Lef1 results in upregulation of CRABP2 and FABP5. Our findings demonstrate that there is dynamic regulation of RA signalling in different regions of the skin and provide evidence for interactions between the RA, β-catenin and Notch pathways.     

NG2 proteoglycan expression in mouse skin: altered postnatal skin development in the NG2 null mouse.

In early postnatal mouse skin, the NG2 proteoglycan is expressed in the subcutis, the dermis, the outer root sheath of hair follicles, and the basal keratinocyte layer of the epidermis. With further development, NG2 is most prominently expressed by stem cells in the hair follicle bulge region, as also observed in adult human skin. During telogen and anagen phases of the adult hair cycle, NG2 is also found in stem cell populations that reside in dermal papillae and the outer root sheaths of hair follicles. Ablation of NG2 produces alterations in both the epidermis and subcutis layers of neonatal skin. Compared with wild type, the NG2 null epidermis does not achieve its full thickness due to reduced proliferation of basal keratinocytes that serve as the stem cell population in this layer. Thickening of the subcutis is also delayed in NG2 null skin due to deficiencies in the adipocyte population.     

Multiple roles for elastic fibers in the skin.

Dermal elastic fibers are believed to have a primary role in providing elastic stretch and recoil to the skin. Here we compare the structural arrangement of dermal elastic fibers of chick skin and different animal species. Most elastic fibers in chick skin are derived from cells that line the feather follicle and/or smooth muscle that connects the pterial and apterial muscle bundles to feather follicles. Elastic fibers in the dermis of animals with single, primary hair follicles are derived from cells lining the hair follicle or from the ends of the pili muscle, which anchors the muscle to the matrix or to the hair follicle. Each follicle is interconnected with elastic fibers. Follicles of animals with primary and secondary (wool) hair follicles are also interconnected by elastic fibers, yet only the elastic fibers derived from the primary follicle are connected to each primary follicle. Only the primary hair follicles are connected to the pili muscle. Human skin, but not the skin of other primates, is significantly different from other animals with respect to elastic fiber organization and probably cell of origin. The data suggest that the primary role for elastic fibers in animals, with the possible exception of humans, is movement and/or placement of feathers or hair.     

Transformation of amnion epithelium into skin and hair follicles

There is increasing interest into the extent to which epithelial differentiation can be altered by mesenchymal influence, and the molecular basis for these changes. In this study, we investigated whether amnion epithelium could be transformed into skin and hair follicles by associating E12.5 to E14.5 mouse amnion from the ROSA 26 strain, with mouse embryonic hair-forming dermis from a wild-type strain. These associations were able to produce fully formed hair follicles with associated sebaceous glands, and skin epidermis. Using beta-galactosidase staining we were able to demonstrate that the follicular epithelium and skin epidermis, but not the associated dermal cells, originated from the amnion. As Noggin and Sonic hedgehog (Shh) were recently shown to be required for early chick ventral skin formation, and able to trigger skin and feather formation from chick amnion, we associated cells engineered to produce those two factors with mouse amnion. In a few cases, we obtained hair buds connected to a pluristratified epithelium; however, the transformation of the amnion was impeded by uncontrolled fibroblastic proliferation. In contrast to an earlier report, none of our control amnion specimens autonomously transformed into skin and hair follicles, indicating that specific influences are necessary to elicit follicle formation from the mouse amnion. The ability to turn amnion into skin and its appendages has practical potential for the tissue engineering of replacement skin, and related biotechnological approaches.     

Hoxa4 expression in developing mouse hair follicles and skin

We have examined the expression of the Hoxa4 gene in embryonic vibrissae and developing and cycling postnatal pelage hair follicles by digoxigenin-based in situ hybridization. Hoxa4 expression is first seen in E13.5 vibrissae throughout the follicle placode. From E15.5 to E18.5 its expression is restricted to Henle's layer of the inner root sheath. Postnatally, Hoxa4 expression is observed at all stages of developing pelage follicles, from P0 to P4. Sites of expression include both inner and outer root sheaths, matrix cells, and the interfollicular epidermis. Hoxa4 is not expressed in hair follicles after P4. Hoxb4, however, is expressed both in developing follicles at P2 and in catagen at P19, suggesting differential expression of these two paralogous genes in the hair follicle cycle.     

Development of interfollicular epidermis on the surface of collagen framework of the dermis in experimental animals]

The fate of interfollicular epidermis keratinocytes which filled the hair follicles bursas of collagen dermis framework was investigated in the autotransplantation experiment. Collagen dermis framework was prepared from the skin flap. Interfollicular epidermis was detached with the help of suction method and transferred to the collagen dermis framework surface which was placed previously on the full thickness skin defect surface. It was established that in this environment keratinocytes not only developed, but some of them migrated into the hair follicle bursas cavities. It resulted in the follicular-like structures formation, cell elements of which differentiated in the manner characteristic of interfollicular epidermis. However, in spite of the fact that the epidermal cells partially retained their proliferating ability, ingrowing would completely disappear by the 15th to 20th day after the transplantation.     

Reprogramming adult dermis to a neonatal state through epidermal activation of β-catenin

Hair follicle formation depends on reciprocal epidermal-dermal interactions and occurs during skin development, but not in adult life. This suggests that the properties of dermal fibroblasts change during postnatal development. To examine this, we used a PdgfraEGFP mouse line to isolate GFP-positive fibroblasts from neonatal skin, adult telogen and anagen skin and adult skin in which ectopic hair follicles had been induced by transgenic epidermal activation of β-catenin (EF skin). We also isolated epidermal cells from each mouse. The gene expression profile of EF epidermis was most similar to that of anagen epidermis, consistent with activation of β-catenin signalling. By contrast, adult dermis with ectopic hair follicles more closely resembled neonatal dermis than adult telogen or anagen dermis. In particular, genes associated with mitosis were upregulated and extracellular matrix-associated genes were downregulated in neonatal and EF fibroblasts. We confirmed that sustained epidermal β-catenin activation stimulated fibroblasts to proliferate to reach the high cell density of neonatal skin. In addition, the extracellular matrix was comprehensively remodelled, with mature collagen being replaced by collagen subtypes normally present only in developing skin. The changes in proliferation and extracellular matrix composition originated from a specific subpopulation of fibroblasts located beneath the sebaceous gland. Our results show that adult dermis is an unexpectedly plastic tissue that can be reprogrammed to acquire the molecular, cellular and structural characteristics of neonatal dermis in response to cues from the overlying epidermis.