tPA, uPA, PAI-1和 PAI-2在人和恒河猴胎盘中的原位杂交和荧光免疫定位(英文)

用原位杂交和荧光免疫定位方法研究了组织型（ｔ）和尿激酶型（ｕ）纤溶酶原激活因子ｔＰＡ、ｕＰＡ和相应的抑制因子ＰＡＩ－１、ＰＡＩ－２在人和恒河猴胎盘中的定位和分布。结果表明：（１）激活因子ｔＰＡ、ｕＰＡ（Ｆｉｇ．１＆４）和抑制因子ＰＡＩ－１（Ｆｉｇ．２）、ＰＡＩ－２（Ｆｉｇ．３）一般都在不同程度上定位于两者胎盘的相同部位;（２）它们主要分布在绒毛干和蜕膜的血管壁、 ＲＯｈｒ’ｓ和Ｎｉｔａｂｕｃｈ’ｓ纹间的基盘外绒毛滋养层细胞、滋养壳、蜕膜细胞和腺体细胞。并且发现;ｔＰＡ和它的抑制因子ＰＡＩ－１更明显地定位于邻近母体组织离层界面的区域,而ｕＰＡ和抑制因子ＰＡＩ－１更集中在绒毛滋养层和外绒毛滋养细胞中;（３）激活因子和抑制因子的ｍＲＮＡ和蛋白的定位和分布基本上一致,但是、在绒毛核体滋养层细胞上未发现其ｍＲＮＡ表达,却有很强的免疫荧光的分布;（４）激活因子和抑制因子合成和分布部位与其作用底物,即纤蛋白类分子的产生部位一致;（５）未发现上述分子在人和恒河猴胎盘分布上的不同。上述实验结果说明,在妊娠的各个阶段 ＰＡ和它的抑制因子协同表达,局限在作用范围很小的特定产生底物的区域。它们的相互作用可能是维持正常妊娠所必需。在妊     

大鼠肝生长发育过程中ACP、AKP、HSC70/HSP68和PCNA的变化(英文)

磷酸酶（ＡＣＰ、ＡＫＰ）在生物的机能分化中起重要作用,热休克蛋白（ＨＳＰｓ）是近几年发现的一类在胚胎发育、细胞生存中起重要作用的分子,无论是胚胎发育还是细胞结构和功能构建都和细胞增殖密切相关,增殖细胞核抗原（ＰＣＮＡ）是检测细胞增殖的良好指标。 本实验用组织化学、免疫组织化学、Ｗｅｓｔｅｒｎ印迹、酶的原位复性电泳、体视学分析等方法定性和定量分析了酸性磷酸酶（ＡＣＰ）（Ｆｉｇ．１＆２）、碱性磷酸酶（ＡＫＰ）（Ｆｉｇ．４＆５）、构成性热休克蛋白 ７０／诱导性热休克蛋白 ６８（ＨＳＣ７０／ＨＳＰ６８）（Ｆｉｇ．６）和ＰＣＮＡ（Ｆｉｇ．７＆８, Ｔａｂｌｅ１）在大鼠肝生长发育（从１４天胚胎到成体）过程中的动态变化。结果表明：（１）在大鼠肝生长发育过程中,ＡＣＰ有两个活性高峰期,其时段处于大鼠吃奶和吃饲料起始期（Ｆｉｇ．１＆２）;（２）在ＡＣＰ的第一个活性高峰期时,ＡＫＰ活性降低;而在ＡＣＰ的第二个活性高峰期时,正值ＡＫＰ的活性高峰期（Ｆｉｇ．３）;（３）ＡＣＰ活性高峰期也是ＰＣＮＡ含量高峰期;（４）ＨＳＣ７０／ＨＳＰ６８在刚断奶的幼鼠肝和成体肝中表达量较多,其他时段表达极少。根据上述结果推测：ＡＣＰ和ＰＣＮＡ通过调节细     

影响火炬松胚性悬浮细胞原生质体的胚胎发生的因素(英文)

火炬松（ＰｉｎｕｓｔａｅｄａＬ．）是我国亚热带和部分热带地区最重要的绿化和造林树种。它的生长周期长,杂合程度高,难以用常规的杂交方法进行品种改良。建立火炬松的原生质体胚胎发生体系,有可能、进而以遗传转化为基础进行火炬松等针叶树的品种改良。本研究以湖南省绍阳市的火炬松成熟种子为材料,建立胚性细胞悬浮系。将其培养至对数生长期,用１％ＲＳ、２．５％Ｒ１０和０．２％Ｙ２３的酶混和液分离原生质体,活力达９０％以上（Ｆｉｇ．１）。纯化原生质体,在再生培养基上培养２天后,细胞壁再生（Ｆｉｇ．２）;;６天后,６５％的原生质体第１次分裂（Ｆｉｇ．３）;培养３周后,形成小细胞团（Ｆｉｇ．４）;６周后,形成大细胞团（Ｆｉｇ．５）;８周后,形成胚性胚柄细胞团（ＥＳＭ）（Ｆｉｇ．６）;１０周后,形成早期体细胞胚（ＥＳＥ）（Ｆｉｇ．７）;１２周后,形成后期体细胞胚（ＬＳＥ）（Ｆｉｇ．８）火炬松原生质体胚形成过程中的关键结构是ＥＳＭ,ＥＳＥ和ＬＳＥ。它们形成的最佳基本培养基是１．２５ＬＰ培养基。再生培养基中高浓度的ＢＡ和低浓度的肌醇有利于ＥＳＭ的形成,但不利于ＥＳＥ和ＬＳＥ的形成。反之,低浓度的ＢＡ和高浓度的肌醇不利于ＥＳＭ的形成,     

大鼠生后发育期间胰腺IAPP免疫组织化学定位研究

本文应用免疫组织化学ＰＡＰ法对正常雄性Ｗｉｓｔａｒ大鼠生后发育期间胰腺ＩＡＰＰ－ＩＲ阳性细胞进行了定位研究。结果表明;生后１天的大鼠胰岛内即已存在ＩＡＰＰ－ＩＲ阳性细胞,双染法证实ＩＡＰＰ与胰岛素共存于胰岛Ｂ细胞的胞质内。ＩＡＰＰ细胞免疫反应强度随生后发育而变化,２８天以后趋于稳定。胰腺外分泌部也有散在的ＩＡＰＰ－ＩＲ细胞。本文初步探讨了上述结果的生物学意义。     

人胎视网膜神经肽Y免疫反应神经元的发育

本文用免疫细胞化学ＡＢＣ法,研究１５—３８周龄人胎视网膜神经肽Ｙ免疫反应（ＮｅｕｒｏｐｅｐｔｉｄｅＹｉｍｍｕｎｏｒｅｃｔｉｖｅ,ＮＰＹ－ＩＲ）神经元（以下称ＮＰＹ－ＩＲ细胞）的发育。结果表明：①胎龄１５周视网膜中央部已出现不同类型的ＮＰＹ－ＩＲ细胞：位于黄斑及其周围外核层的为ＮＰＹ－ＩＲ视锥细胞;位于内核层最内一列的为ＮＰＹ－ＩＲ无长突细胞位于节细胞层的可能为ＮＰＹ－ＩＲ移位无长突细胞或节细胞;内核层和节细胞层的ＮＰＹ－ＩＲ细胞的突起均分布在内网层的第１亚层。②胎龄２４周后,ＮＰＹ－ＩＲ视锥细胞完全消失。③随着视网膜的发育,内核层和节细胞层的ＮＰＹ－ＩＲ细胞数量增多,突起增粗增长,胞体分布由中央部扩展到周边部,其中内核层ＮＰＹ－ＩＲ细胞的密度呈现从中央部向周边部逐渐降低的分布方式,节细胞层ＮＰＹ－ＩＲ细胞则多数集中分布在视网膜的边缘和黄斑之间,形成较高密度的环状区。     

糖链结构不同的纤连蛋白与HT1080细胞结合研究

人血浆纤连蛋白（Ｆｉｂｒｏｎｅｃｔｉｎ,Ｆｎ）与人胎盘纤连蛋白两者在肽链结构上基本相同,但人血浆Ｆｎ的Ｎ－糖链结构为二天线结构,而人胎盘Ｆｎ不仅Ｎ－糖链的数量增加,同时还含有多天线结构,分别用~（１２５）Ｉ标记这两种具有不同糖链结构的Ｆｎ,观察两者与ＨＴ１０８０细胞的饱和结合的亲和性,结果发现,在４℃,人血浆Ｆｎ与ＨＴ１０８０细胞的饱和结合为１２９ｎｇ／１０~５细胞,解离常数为２．８３×１０~（－８）ｍｏｌ／Ｌ,人胎盘Ｆｎ与ＨＴ１０８０细胞的饱和结合为１３３ｎｇ／１０~６细胞,解离常数为２．６４×１０~（－８）ｍｏｌ／Ｌ．因而,人血浆Ｆｎ与人胎盘Ｆｎ上Ｎ－糖链的不同并未影响其与受体的结合．     

用RAPD法研究火炬松愈伤组织发生的遗传特性(英文)

体外培养对于植物的快速繁殖是非常有效的。和其它一些松果类硬木植物一样,火炬松的体外培养成功率却一直很低。本工作研究了不同的基本培养基和低温条件对于火炬松Ｊ－５６, Ｓ－１００３, ａｎｄ Ｅ－４４０等三个品系的成熟合子胚形成愈伤组织、分化出芽、成苗的影响。在不同的基本培养基条件下芽分化的程度差异很大。合子胚经过９－１２周培养,开始分化,形成具有器官发生的愈伤组织（Ｆｉｇ．２ａ）。分化后３周,开始诱导出芽（Ｆｉｇ．２ｂ）,芽的生长快慢不同（Ｆｉｇ．２ｃ,ｄ）。同一个愈伤组织上会生出几个芽来（Ｆｉｇ．２ｅ）。在添加有ＩＢＡ和ＢＡ的ＴＥ培养基上芽生长最快（Ｆｉｇ．１）。低温条件持续 １５天,能增加芽的数量和分化的程度（Ｔａｂｌｅ１）。上述培养基中增加ＧＡ３时表明,ＧＡ３对于根的诱导有决定性的作用。将９８株再生苗转移到特殊的混合土壤上;成活了７５株苗（Ｆｉｇ．２ｆ）。以这三种火炬松的再生苗尖为材料制备ＤＮＡ。用２０个引物进行ＲＡＰＤ分析,结果表明：这三种火炬松苗的扩增产物是相同的（Ｆｉｇ．２ｇ,ｈ＆ｉ）。这说明：用愈伤组织克隆植株的过程中没有引起植物遗传变异。     

地塞米松诱导红系细胞凋亡的观察(英文)

正常机体内,红细胞生成素（ＥＰＯ）诱导红系细胞分化,并阻止其凋亡,使其维持机体所需足够的数量。本文采用诱发贫血病毒（ＦＶＡ）诱导ＢＡＬＢ／ｃ小鼠脾细胞所形成的红细胞为实验系统,研究了外界因子？？地塞米松（Ｄｅｘ）对ＥＰＯ作用的影响。取６８周雌性ＢＡＬＢ／ｃ小鼠,尾部静脉注射含ＦＶＡ的小鼠血清。１５天后,断颈处死。取脾于ＩＭＤＭ中漂洗、剪碎、过滤、离心、制成单细胞悬液,在ＥＰＯ存在下,于平皿中培养至不同的时期后,进行不同浓度、不同时间的Ｄｅｘ处理。取细胞进行：（１）台盼蓝染色计数死细胞数;（２）观察ＤＮＡ电泳图谱;（３）电镜检察细胞学变化。Ｆｉｇ．１表明：随着Ｄｅｘ处理浓度和时间的增加,细胞死亡率也增加。Ｆｉｇ．２表明：１０－４浓度Ｄｅｘ处理,即可使早（１２ｈ）、中（２４ｈ）幼期红细胞凋亡,ＤＮＡ断裂成多聚核小体,产生明显ＤＮＡ梯形带。Ｆｉｇ．３表明：高浓度Ｄｅｘ可以使早幼期红细胞凋亡。电镜观察表明：与对照（Ｆｉｇ．４）比较,Ｄｅｘ处理后,细胞核固缩,染色质沿核膜内面周边凝聚,核周间隙扩张,胞质内出现空泡（Ｆｉｇ．５）;随后细胞破碎,出现大量凋亡小体（Ｆｉｇ．６）。Ｄｅｘ拮抗ＥＰＯ,诱导红系细胞凋亡的现象此     

朱顶红生殖细胞胞质分裂的两种方式(英文)

大多数植物以形成细胞权方式完成胞质分裂过程,也有些植物以类似于动物和单细胞植物在赤道区形成收缩沟的方式而分成两部分。本工作应用电镜对朱顶红体外萌发９～１８小时花粉管中的生殖细胞胞质分裂进行了研究。结果表明：７０％的细胞表现的是第一种方式、３０％却是第二种方式。即：朱顶红生殖细胞胞质分裂同时存在两种方式。前者最初以细胞板亚单位的形式出现于有丝分裂晚后期,它们聚集于成膜体的中央区域并于分裂末期融合成一个大的连续的单位（Ｆｉｇ．１～３）。大量新的微管形成于两组染色体之间（Ｆｉｇ．１）。分裂末期,细胞板形成并具胞质通道（Ｆｉｇ．２）。成膜体微管规则排列并穿过胞质通道向新形成的末期核伸展（Ｆｉｇ．２＆３）。这些微管与构成细胞板的质膜紧密联系（Ｆｉｇ．３）。后者则在有丝分裂后期开始（Ｆｉｇ．４）,当两群染色体彼此分离时,生殖细胞质膜在中央区由两侧向内凹陷形成收缩沟。有时生殖细胞几乎被收缩沟分成两个部分（Ｆｉｇ．６）。发生缢缩的细胞中细胞器与具细胞板的无差异,但微管稀少并且排列紊乱（Ｆｉｇ．４＆５）,染色体的状态使得难以准确区分细胞分裂时期。而且核膜的形成似乎始于有丝分裂后期、出现于染色体边缘（Ｆｉｇ．７）。有时尚有落后     

豚鼠腹腔神经节迟慢兴奋性突触后电位与5－HT和P物质的关系

应用细胞内记录,研究了豚鼠腹腔神经节（ＣＧ）细胞非胆碱能迟慢兴奋性突触后电位（ＬＳ－ＥＰＳＰ）与５－羟色胺（５－ＨＴ）及Ｐ物质（ＳＰ）的相互关系。当重复电刺激内脏大神经（ＳＮ）时,有７８．２％的细胞（１６１／２０６）在动作电位发放后出现ＬＳ－ＥＰＳＰ,灌注或压力注射５－ＨＴ或ＳＰ,分别在６８．５％的细胞（１０２／１４９）及５２．１％的细胞（９８／１８８）上引起５－ＨＴ或ＳＰ去极化反应,两者差异非常显著（Ｐ＜０．０１）;大部分具有ＬＳ－ＥＰＳＰ的细胞对５－ＨＴ（７３／８８,８３．０％）或ＳＰ（６８／１１４５９．６％）敏感,而不出现ＬＳ－ＥＰＳＰ的细胞仅有少数对５－ＨＴ（１０／２６,３８．５％）或ＳＰ（１１／３６,３０．６％）敏感,两类细胞的差异非常显著（５－ＨＴ：Ｐ＜０．０００１,ＳＰ：Ｐ＜０．０１）。上述结果支持５－ＨＴ与ＳＰ均作为递质参与ＬＳ－ＥＰＳＰ形成的观点。此外,在１３３个细胞上同时检测了５－ＨＴ与ＳＰ的作用,其中有６６个细胞（４９．６％）对５－ＨＴ及ＳＰ均敏感,提示在ＣＧ细胞,５－ＨＴ与ＳＰ之间可能存在某种机能联系。     

IAPP与SS在大鼠和家兔背根神经节细胞内分布与共存的免疫组织化学研究

应用免疫组织化学ABC法,观察到在大鼠和家兔背根神经节内存在胰岛淀粉样多肽免疫阳性反应细胞.用相邻镜像邻片免疫双标记技术,证实胰岛淀粉样多肽存在于背根神经节内那些生长抑素免疫反应阳性的细胞中,说明胰岛淀粉样多肽在大鼠和家兔背根神经节内与生长抑素共存.实验结果为胰岛淀粉样多肽的胰腺外研究提供了新的资料,为进一步研究背根神经节内生物活性物质间的关系及生理作用提供了形态学证据.     

人胎杏仁核基底外侧核群含一氧化氮合酶神经元的发育

用组织化学方法研究了人胎杏仁核基底外侧核群含一氧化氮合酶（ＮＯＳ）神经元的发育。胎龄分别为１６,２１,２３,２８,３１,３８周。ＮＯＳ阳性神经元在基底外侧核群存在有两种不同的发育模式。１．在外侧核和基底核,单位面积内的阳性细胞数分别在２１周,２３周时较多,随后渐减,从３１～３８周又开始增多。２．在付基底核,２１周时阳性细胞数较多,２３周时减少,随后渐增多。从３１～３８周又渐减少。ＮＯＳ阳性神经元在整个基底外侧核群内的均面积的变化,从１６～２８周ＮＯＳ阳性神经元的均面积是渐增大的,从２８～３１周有所减少。从３１～３８周又渐增大。结果提示,ＮＯＳ阳性神经元出现于人胎基底外侧核群的发育早期,在此核的发育过程中起着很重要的作用     

Morphometric studies on the development of human thyroid gland in early fetal life.

Histological and morphometric studies were performed on 30 thyroid glands obtained from normal human fetuses. Their crown-rump length (CRL) ranged from 57 to 190 mm, corresponding to the gestational age of 10-20 weeks. The weight of the thyroid gland increased proportionally in relation to CRL, foot length and fetus weight. The first follicles containing PAS-positive colloid were observed in the peripheral part of the thyroid gland of 57 mm CRL fetus. The number of follicles per 1 mm2 of thyroid surface section increased up to 85 mm CRL and thereafter gradually declined for the end of studied period of fetal life. The volumes (in mm3) of thyroid epithelium, colloid and stroma, beginning from 85 mm increased proportionally to the CRL while the height of epithelial cells did not change. The epithelium/colloid ratio decreased notably to 165 mm CRL and thereafter remained constant. Results of the present study suggest that the thyroid gland of human fetus approaches structural maturity in 17.5 week of gestation.     

Ontogeny of endocrine cells in the respiratory system of Syrian golden hamsters

The ontogeny of protein gene product 9.5 (PGP 9.5), serotonin (5-HT), calcitonin gene-related peptide (CGRP), and calcitonin (CT) immunoreactivity was evaluated in small-granule endocrine cells of hamster laryngotracheal epithelium from fetal day 11 to adulthood. Two centrifugal (proximal-to-distal) patterns of differentiation occur. The first pattern begins during fetal life. Endocrine cells, single and clustered in groups (presumptive-or protoneuroepithelial bodies, pNEBs), initially colocalize immunostaining for PGP 9.5, 5-HT, and CGRP in the larynx and proximal 2/3 of the trachea on day 12 and spread to the caudal trachea on day 13.5-HT disappears fleetingly during the 24 h preceding birth; other-wise immunoreactivity for all three substances persists into adulthood. The clusters of endocrine cells survive beyond birth but are so diluted by expansion of the nonendocrine epithelium as to become inconspicuous. Since innervation was not actually observed, these clusters may persist as pNEBs, without developing connections to afferent or efferent nerve fibers. The second pattern concerns single small-granule cells stainable for CGRP but not for 5-HT. These cells first appear in the larynx and cartilaginous part of the cranial trachea on postnatal day 3, and in the middle and caudal trachea, on day 5. The cells increase in number on day 7. In adults, they predominate among endocrine cells of the cartilaginous region. A subset of these cells begins to co-express CT proximally on postnatal day 10, reaching the caudal end of the trachea by 3 weeks. A few elements of the older 5-HT-positive population may also become immunoreactive for CT in juvenile hamsters.     

Expression of the androgen receptor and 5α-reductase type 2 in the developing human fetal penis and urethra

Normal penile development is dependent on testosterone, its conversion via steroid 5 alpha-reductase type 2 to dihydrotestosterone, and a functional androgen receptor (AR). The goal of this study was to investigate the distribution of AR and 5 alpha-reductase type 2 in the developing human fetal external genitalia with special emphasis on urethra formation. Twenty fetal genital specimens from normal human males (12-20 weeks gestation) were sectioned serially and stained by avidin-biotinylated peroxidase complex method with antigen retrieval. Stained sections throughout male genital development documented the expression of AR and 5 alpha-reductase type 2 in the phallus. Between 12 and 14 weeks of gestation, AR was localized to epithelial cells of the urethral plate in the glans, the tubular urethra of the penile shaft, and stromal tissue surrounding the urethral epithelium. In the fetal penis between 16 and 20 weeks gestation, the density of AR expression was greatest in urethral epithelial cells versus the surrounding stromal tissues. There was a characteristic pattern of AR expression in the glandular urethral epithelium between 16 and 20 weeks gestation. AR expression was greater along the ventral aspect of the glandular urethra than along the dorsal aspect of the urethral epithelium. The expression of 5 alpha-reductase type 2 was localized to the stroma surrounding the urethra, especially along the urethral seam area in the ventral portion of the remodeling urethra. These anatomical studies support the hypothesis that androgens are essential for the formation of the ventral portion of the urethra and that abnormalities in either the AR or 5 alpha-reductase type 2 can explain the occurrence of hypospadias.     

Fetal gender determination in early pregnancy through qualitative and quantitative analysis of fetal DNA in maternal serum

Fetal DNA in maternal plasma and serum has been shown to be a useful material for fetal gender determination and for screening tests for abnormal pregnancies except during early gestational ages. Maternal serum samples were obtained from 81 pregnant women during the 5th-10th weeks of gestation. Fetal gender was determined by conventional polymerase chain reaction (PCR) to detect a Y-chromosomal sequence (DYS14) in maternal serum during early gestation and confirmed by examination of the newborns after delivery. Real-time quantitative analyses of the SRY and beta-globin genes were also performed in order to determine fetal gender and to quantify fetal DNA concentration in maternal serum during early gestation. When using conventional PCR, the total sensitivity of identifying a male fetus was 95%, but its sensitivity after the 7th week was 100%, whereas in real-time quantitative PCR, the total sensitivity after the 5th week was 100%. Quantitative analyses of the SRY gene revealed that the mean concentration of fetal DNA in maternal serum was 30.55 copies/ml, that fetal DNA concentration showed a tendency to increase with the progression of pregnancy, and that it had a wide normal range. Thus, we could confidently determine fetal gender by using maternal serum samples taken as early as the 7th week.     

Functional maturation of the human corticotropin releasing factor-adrenocorticotropic hormone system during intrauterine life. An in vitro study

Radioimmunoassay was used to determine ACTH secretion by cultured hypophyses of human fetuses from the 6th to the 30th week of intrauterine life and their responsiveness to hypothalamic extracts obtained from adult animals. CRF-like activity in the human hypothalamus was measured within the 6th to the 32nd week of prenatal development from changes in ACTH release by cultured cells of the adult rat hypophysis. It was established that starting from weeks 6-7 of embryogenesis, the human fetal hypophysis is capable of synthesizing and secreting immuno-reactive ACTH in vitro. The human fetus hypothalamus of the first trimester of gestation contained no CRF-like substance. The fetus hypothalamus of the second and third trimesters of pregnancy manifested a considerable amount of CRF-like substance. It is suggested that CRF appears at the end of the first trimester of pregnancy.     

The involvement of proliferation and apoptosis in the early human gonad development

Distributions of the Ki-67, TP53, caspase-3 and AIFM1 markers were histologically investigated in the 5th to 9th week developing gonads of 12 human conceptuses using immunohistochemical and immunofluorescence methods. Between the 5th and 8th developmental week, proliferation gradually increased in the surface gonad epithelium (26–52 %) and stroma (19–42 %), but then slightly decreased in the surface epithelium (35 %) during the early foetal period. In medulla, low proliferation activity decreased from 15 to 12 % between the 7th and 9th week. At earliest stages of gonadal development, primordial germ cells (PGC) were only rarely TP53 positive. In the 7th and 8th week, almost all PGC-s displayed TP53 positivity, while their number decreased in early fetal period. During the investigated period, caspase-3 reactivity gradually decreased in surface epithelium, while it increased in PGC and medulla of developing gonad AIFM1-positivity first appeared in surface gonad epithelium and then predominantly in PCG-s while caspase-3 characterized different cell populations within the developing gonad. AIFM1 and caspase-3 co-localized only during the migration of PCG-s. The number and distribution of Ki-67, TP53, caspase-3 and AIFM1 reacting cells changed coincidently with development end regression of the sex cords in indifferent and early fetal gonad. Our results indicate that the number of PGC might be controlled by balance of TP53 and AIFM1, leading to caspase-3 independent cell death. Other cell populations are probably eliminated by caspase-3-dependent cell death. Both pathways of cell death seem to operate during early human gonad development, while their intensity varies depending on the cell type and developmental period analysed.     

Development of the omasum in sheep

Data are presented on the histogenesis of the omasal mucosa in sheep from the 2.5 cm crown-rump (c-r) length fetus to the adult. 11 stages of fetal development, and 4 post-natal stages, were studies. The distribution of glycogen in the omasal epithelium was also studied. During fetal life the omasal epithelium was initially stratified cuboidal in type, but the superficial layers of cells became flattened in later stages of gestation. This epithelium became extremely thick by the late stages of fetal life, reaching a maximum of 358 micron, and consisting of greater than 20 layers of cells, in the 45 cm c-r fetus (approximatelay 140 days). After birth the epithelium became markedly reduced in thickness, being approximately 77 micron in the adult, and had differentiated into a cornified stratified squamous epithelium of the adult type by 12 weeks after birth. Glycogen was extremely abundant in the omasal epithelium of the 2.5 cm fetus, and declined gradually thereafter to be almost completely absent in post-natal specimens. 4 orders of laminae were present in the adult omasum, distributed in the seqeunce 1-4-3-4-2-4-3-4-1. The 1st order was already present in fetuses of 2.5 cm c-r length, with the 2nd, 3rd and 4th appearing by the 3.5, 5.5 and 11.0 cm stages, respectively. Initial stages in the development of conical papillae were first seen in 15.0 cm fetuses, but the development of these papillae was not completed until after birth.     

Proliferation and apoptosis in the epithelium of the developing human cornea and conjunctiva.

To determine the distribution of proliferating and apoptotic cells in the human cornea during prenatal and early postnatal development, we examined sections of the bulbar conjunctiva, the limbus as well as the central and peripheral cornea between 11 weeks of gestation and 6 months after birth. The objective was to localize dividing cells by proliferating cell nuclear antigen-like immunoreactivity (PCNA-LI) and apoptotic cells by terminal transferase-mediated nick-end labeling (TUNEL). Before the 17th gestational week, PCNA-LI was absent in all 4 regions examined, indicating negligible cell proliferation during early development. After 20 weeks, strong PCNA-labeling was observed in all regions examined suggestive of high proliferative activity not only in the limbus and the bulbar conjunctiva, but also in the central and peripheral cornea. This rise in proliferative activity was followed by a steady decline: after 28 weeks, anti-PCNA staining gradually disappeared in the central and peripheral cornea, so that, at 6 months after birth, it was confined to the limbus and the bulbar conjunctiva, resembling the picture described for the adult cornea. TUNEL-positive cells were virtually absent in all 4 regions examined before the 38th gestational week. Apoptotic cells only started to appear at 38 weeks; at this stage, they were confined to the bulbar conjunctival epithelium. At 6 months after birth, TUNEL-positive cells were observed in the bulbar conjunctival epithelium and the entire cornea; the limbus, however remained devoid of apoptotic cells throughout the entire prenatal and early postnatal period. The present study for the first time localizes proliferating and apoptotic cells in the epithelium of the developing human cornea. Three stages of development can be distinguished: Minimal proliferation (until 17th week), vigorous proliferation over the entire cornea including the limbus and the bulbar conjunctiva (until 28th week) and gradual decrease in proliferative activity (after 28th week) accompanied by the appearance of apoptotic cells.