根田鼠视网膜的胚后发育

视觉对动物的生活习性尤其是取食具有重要意义。本文对根田鼠视网膜的胚后发育进行了研究,结果表明:出生3d内根田鼠视网膜分化程度较低,神经节母细胞层尚未分化,占据了视网膜层的一半以上;5日龄时,外网层开始出现;6日龄时,外网层开始清晰,外核层与内核层更加清晰;18日龄时,视网膜结构与成年根田鼠结构相似,各层结构清晰可见。测量了神经节细胞层和外核层的细胞密度以及核层厚度,结果表明:随着个体发育,外核层细胞层厚度及细胞密度不断增加;而神经节细胞层厚度及细胞密度不断减少。与褐家鼠、黑线姬鼠、大仓鼠、棕色田鼠、甘肃鼢鼠、达乌尔黄鼠、岩松鼠视网膜相比,根田鼠视网膜结构介于夜行性与昼行性鼠类之间[动物学报52(2):376-382,2006]。     

不同胚龄北京鸭视网膜节细胞层细胞大小、数量及密度

采用视网膜铺片Nissl染色法和Scion Image图像分析法,研究北京鸭胚胎期11（E11）、14、117、20、23和26日龄视网膜节细胞层（Ganglion cell layer,GCL）细胞大小、数量及密度分布变化。结果表明：E11-E14,GCL细胞小,均呈圆形,E17开始出现大细胞;E11至E26视网膜中央区（CA）细胞大小增长1．97倍,而颞侧周边区（TP）增长3．1倍,相邻胚龄间细胞大小差异显著。GCL细胞总数在E17达到最大值2．03×10^6个,随后细胞数量显著下降。视网膜中央-周边密度梯度在E11出现。CA细胞密度在E17达到最大值2．54×10^4个/mm^2,随后密度下降;周边区细胞密度随胚龄增长而持续下降,且TP细胞密度下降最显著。结果提示,北京鸭胚胎发育过程中,GCL细胞大小、数量及密度均发生显著变化,而E17是其中的一个重要转折点[动物学报54（6）：1082—1088,2008]。     

不同胚龄大鼠胚胎组织切片制作体会

全胚切片标本是发育生物学教学及其相关研究的基础。本实验采用石蜡包埋和免疫组织化学技术对如何制作完整和连续的不同胚龄之全胚切片进行了探索,并研究了亨廷顿相关蛋白1在孕中期胚鼠的表达。     

胚龄和激素对小麦幼胚组织培养的影响

以扬麦158为试验材料,通过田间取样室内培养的方法研究了胚龄和激素对小麦幼胚组织培养的作用。结果表明,幼胚组织培养最适宜的胚龄为14—16d;适宜的2,4-D浓度为1．5-2．5mg/L;适宜的IAA浓度为2．0-3．0mg/L;适宜的6-BA浓度为0．1-0．8mg/L;适宜的KT浓度为0．5—1．5mg/L。因此,胚龄和激素对于小麦幼胚组织培养具有明显的调节作用．在组织培养实践中,充分认识和综合协调这些因素对小麦幼胚组织培养的作用,可以提高组织培养效率,使其更加有利于生物学研究、遗传转化和快速育种等工作。     

2，4-D诱导的花生体细胞胚发生的组织学研究

花生成熟胚胚叶在MS附加 2 0mg/L 2 ,4_D的培养基上诱导 2 0d后 ,转移至无激素培养基MS0 继续培养 ,可获高频体细胞胚发生。组织学观察表明 ,体细胞胚起源于胚叶上表皮及表皮下数层细胞 ,这些细胞脱分化形成细胞质浓厚、细胞核大的胚性细胞团 ,胚性细胞团继续分裂形成体细胞胚。体细胞胚的发育过程经历球形胚、心形胚、鱼雷胚、子叶胚四个时期     

2,4-D诱导的花生体细胞胚发生的组织学研究

花生成熟胚胚叶在佃附加20mg/L 2,4-D的培养基上诱导20d后,转移至无激素培养基MS0继续培养,可获高频体细胞胚发生。组织学观察表明,体细胞胚起源于胚叶上表皮及表皮下数层细胞,这些细胞脱分化形成细胞质浓厚、细胞核大的胚性细胞团,胚性细胞团继续分裂形成体细胞胚。体细胞胚的发育过程经历球形胚、心形胚、鱼雷胚、子叶胚四个时期。     

离体培养下大豆体细胞胚胎发生的组织学研究

大豆胚状体可以直接从未成熟的子叶表皮及表皮下面1—3层细胞发生。这些细胞经过脱分化后,首先形成细胞质浓厚、核大的胚的发生细胞,胚发生细胞再分裂形成胚性细胞团,胚性细胞团再继续分裂形成胚状体。胚状体的发育过程和合子胚一样,经过球形、心形,鱼雷期和子叶期等诸阶段发育成小植株。此外,在诱导胚状体发生过程中,还观察到另一值得注意的现象:在未成熟胚的子叶表皮下面1至较深处的数层细胞,也转变成分生状细胞团,这些分生状细胞团呈不规则状,从其起源看,可称它们为内生“胚状体”,这些内生“胚状体”培养至20天,即停止生长发育。     

四指马鲅视网膜早期发育的组织学研究

本文采用石蜡连续切片技术、H.E染色和显微测量法,对四指马鲅(Eleutheronema tetradactylum)早期发育过程中视网膜的结构、分化和形成过程以及视觉特性进行了研究。结果显示,受精后8 h54 min,视杯已经形成。初孵仔鱼视网膜没有分化。2日龄仔鱼可以清晰的辨认出色素上皮层、外核层、内核层和神经节细胞层。3日龄仔鱼内核层已经分化出水平细胞、双极细胞和无长突细胞。4日龄仔鱼视网膜10层结构完整。9日龄至14日龄,外核层胞核数目与神经节细胞数目的比值增大,视网膜会聚程度升高,是该鱼视觉特性发生变化的过渡期,这与其从浮游到浅海中下层和泥沙质海底活动的生态迁移相适应。在生长发育的早期阶段,其视网膜内核层水平细胞仅有1到2层,属于感光系统不甚发达的类型。该鱼在仔鱼浮游生活阶段,视敏度较高,视觉对其行为和摄食活动具有重要作用,适应生活于光照较充足的环境中,转入浅海中下层和泥沙质海底后,光敏度和视敏度均较差,视觉在其行为和摄食活动中不具有主要作用。     

细菌鞭毛染色菌龄初试

细菌鞭毛染色的适宜菌龄,一般在10—24小时之间,但在实践中发现,不同种细菌染色菌龄有不同特点。普通变形菌、铜绿色假单胞菌和大肠埃希氏菌都是无芽孢菌,因而不会由于产生芽孢而使鞭毛脱落,所以染色菌龄较长,从4小时开始,到24、48、72小时均可进行染色,结果也比较理想。可见,这几株菌的鞭毛染色几乎不受菌     

秦岭滑蜥视网膜年龄相关的显微结构特征和胶质纤维酸性蛋白免疫组织化学定位

光学显微镜下观察了秦岭滑蜥Scincella tsinlingensis视网膜年龄相关的显微结构特征,并对胶质纤维酸性蛋白(GFAP)免疫组织化学定位及表达强度进行了统计分析。结果显示:秦岭滑蜥视网膜由内至外共分为10层,与昼行性蜥蜴类视网膜结构特征一致。亚成体和成体视网膜总厚度较幼体明显增加,但三者神经节细胞层、外界膜以及视杆视锥层厚度之间无明显差异。不同年龄组视网膜细胞核层数无差异:外核层1~2层,神经节细胞层3~4层,内核层6~8层。视网膜GFAP免疫阳性主要定位于内界膜和神经纤维层,且神经纤维层阳性最强。GFAP阳性表达呈现成体最强、幼体较强、亚成体最弱的年龄相关性,这可能与视网膜胚后发育中的生理功能调节相关。     

大熊猫雌性个体发情期生殖内分沁变化的研究

本文首次报道了用黄体生成素的生物测定法测定大熊猫发情期黄体生成素的生物活性与雌二醇、孕酮的关系。雌性大熊猫在发情高潮后两天,尿中黄体生成素的生物活性与雌二醇同时出现峰值,并与雄性变配。随后尿中孕酮浓度迅速增长,其浓度远远大于发情前期的水平。生殖内分泌的变化证实:雌性大熊猫在发情期中有成熟的卵子排出。     

Formation of neuroblastic layers in chicken retinospheroids: the fibre layer of Chievitz secludes AChE-positive cells from mitotic cells

Summary The significance of the classical subdivision of the retinal primitive neuroepithelium into an outer and an inner neuroblastic layer by the transient fibre layer of Chievitz (LOC) is little understood. We examine here the formation of neuroblastic layers by regenerating fully laminated retinospheroids from dissociated cells of the embryonic chick eye margin in rotary culture. By tracing cellular processes with the fibre-specific F11-antibody in retinospheroids, we occasionally find, in addition to an outer and an inner plexiform layer, a cell-free F11-positive LOC homologue, subdividing the inner nuclear layer. Moreover, we demonstrate that the LOC precisely separates postmitotic AChE-positive cells of the inner retina from an AChE-negative outer part holding all BrdU-labelled mitotic cells. These in vitro data suggest that the inner neuroblastic layer is exclusively composed of AChE-positive cells, thus representing a primary differentiation zone of the retina.     

Dlx1 and Dlx2 function is necessary for terminal differentiation and survival of late-born retinal ganglion cells in the developing mouse retina

Dlx homeobox genes, the vertebrate homologs of Distal-less, play important roles in the development of the vertebrate forebrain, craniofacial structures and limbs. Members of the Dlx gene family are also expressed in retinal ganglion cells (RGC), amacrine and horizontal cells of the developing and postnatal retina. Expression begins at embryonic day 12.5 and is maintained until late embryogenesis for Dlx1, while Dlx2 expression extends to adulthood. We have assessed the retinal phenotype of the Dlx1/Dlx2 double knockout mouse, which dies at birth. The Dlx1/2 null retina displays a reduced ganglion cell layer (GCL), with loss of differentiated RGCs due to increased apoptosis, and corresponding thinning of the optic nerve. Ectopic expression of Crx, the cone and rod photoreceptor homeobox gene, in the GCL and neuroblastic layers of the mutants may signify altered cell fate of uncommitted RGC progenitors. However, amacrine and horizontal cell differentiation is relatively unaffected in the Dlx1/2 null retina. Herein, we propose a model whereby early-born RGCs are Dlx1 and Dlx2 independent, but Dlx function is necessary for terminal differentiation of late-born RGC progenitors.     

Immunocytochemical localisation of neuronal nitric oxide synthase in developing and transplanted rabbit retinas

 Nitric oxide (NO) acts as a modulator of neuronal transmission in mature neuronal systems, including the retina. Recently, NO has also been suggested to have a trophic function during development. We examined immunocytochemically the distribution of NO-producing cells in developing and transplanted rabbit retinas. An antibody detecting the neuronal isoform of its biosynthetic enzyme, nitric oxide synthase (NOS), was used on normal developing retinas [starting at embryonic day (E) 15] and on rabbit retinal transplants after various survival times (1–139 days after surgery). Weakly stained cell bodies were first observed in the proximal margin of the neuroblastic layer at E 29. Stained processes projecting towards a developing inner plexiform layer were also visible at this time point. Immunoreactive cells were located at later stages in the innermost part of the inner nuclear layer and in the ganglion cell layer, and are likely to correspond mainly to amacrine cells. NOS-labelled cells were also found in retinal transplants. The first NOS-labelled cells appeared, as in normal developing retinas, in ages corresponding to E 29 and were still detected in transplants corresponding to postnatal day 123. NOS-labelled cells were seen in areas between rosettes, where amacrine cells are located. NOS-labelled processes were at times seen to project for long distances, forming very distinct plexuses. NOS-containing amacrine cells thus appear both in the transplants and in developing retinas in the embryonic stages, long before synaptic function involving these cells can be expected, suggesting a role for NO not only in neuromodulation but also in retinal development. Accepted: 22 January 1997     

Distribution of transferrin and transferrin receptor of the eype 1 in the process of formation of the rat eye retina in early postnatal ontogenesis

By the method of indirect immunohistochemistry, distribution of transferrin and of transferrin receptor of the type 1 (TFR1) was studied in the formed rat eye retina at the period of early postnatal ontogenesis (from birth to opening of eyelids). It has been established that the character of distribution of these proteins and intensity of specific staining change dependent on the retina formation stage. Retina of the newborn rat is characterized by diffuse transferrin distribution in nuclear retina layer (in the neuroblast layer-NBL) and in the ganglionic cell layer (GCL) as well as in the eye pigment epithelium (PE); relative immunoreactivity to transferrin is not high. At the 5th postnatal day, immunoreactivity to transferrin is maximal and is revealed both in nuclear and in plexiform layers of retina and in the eye PE, the greatest signal being characteristic of NBL. At the 10th postnatal day the transferrin signal intensity in retina decreases, specific staining is revealed in GCL, PE, and in the area of formed outer segments of photoreceptors. At the 15th postnatal day, transferrin is revealed in GCL, in outer and inner photoreceptor segments and in the eye PE. TFR1 is present in all retina layers at all stages of the retina formation; the relative immunoreactivity to TFR1 sharply rises beginning from the 10th postnatal day; correlation between distribution of transferrin and TFR1 is detected in the entire retina of newborn rats as well as in the external retina area at subsequent stages of its development. A possible role of transferrin at various stages of formation of retina is discussed.     

THE ROLE OF THE PIGMENT EPITHELIUM IN THE ETIOLOGY OF INHERITED RETINAL DYSTROPHY IN THE RAT

Visual cell outer segment renewal was studied in eyes of mutant Royal College of Surgeons (RCS) and Sprague-Dawley (control) rats by a combination of microscopy and radioautography with the light and electron microscopes. RCS and control rats were injected with amino acids-³H at 11 days of age. Radioactive rod outer segment discs were assembled at the outer segment base from radioactive proteins synthesized in the rod inner segments. In controls, all radioactive discs assembled at 11 days of age were displaced the length of the outer segments, removed from outer segment tips, and phagocytized by the pigment epithelium by 8 days after injection. In the RCS rats, disc assembly and displacement resembled controls for the first 3 days after injection. However, as disc assembly continued for some time thereafter, a layer of labeled, disorganized, lamellar debris accumulated between the outer segment tips and the pigment epithelium. The buildup of debris was accompanied by visual cell death. At no time during the study was there evidence for phagocytic activity by the pigment epithelium. 61 days after injection, the layer of debris was the only heavily radioactive component in the retina. In the retina of RCS rats, the outer segment renewal mechanism malfunctions because the pigment epithelium does not fulfill its normal phagocytic role. The end result is visual cell death and blindness.     

Differential effect of dopamine on mitosis in early postnatal albino and pigmented rat retinae

Insufficient levels of L-DOPA, released from the retinal pigment epithelium (RPE), in albino animals are considered responsible for the abnormal development of the underlying neural retina. L-DOPA normalizes retinal neurogenesis by reducing levels of cell proliferation either by acting on the cells directly or by being converted into dopamine. Here we report the effects of dopamine on mitosis in early postnatal neural retinae from albino and pigmented rats, using 4D (x, y, z and time) confocal microscopy. Exogenous dopamine significantly prolongs mitosis in retinae from albino, but not pigmented, animals. As fewer cells move into and divide in the ventricular zone (VZ) in the presence of dopamine, we conclude that the overall cell cycle is affected. The D1 receptor blocker, SCH 23390, inhibits these effects. Thus, the differential effects of dopamine on neural retinae from pigmented and albino rats in vitro must result from the activation of D1 receptors, which are present in the retina from birth. Immunohistochemical labeling of D1 receptors shows that the pattern of their distribution is similar between pigmentation phenotypes, but levels of expression may be elevated in albinos. Labeling is most intense in the inner plexiform layer but is present throughout the neuroblastic layer. These findings are discussed in light of previous reports of reduced catecholamine levels in the albino retina.     

移植视网膜NOS阳性神经元的发育

目的 观察不同年龄组段大鼠正常视网膜及移植视网膜内NOS阳性神经元的发育情况及其定位分布。方法 实验分正常视网膜发育组和移植视网膜发育组,应用还原型烟酰胺腺嘌呤二核苷酸磷酸（NADPH）组织化学方法显示。结果 1、NOS阳性神经元最早出现于生后第五天（P5）,P18时阳性神经元数目达到最高峰,2、移植视网膜具有正常视网膜的各层结构和相似的生长规律,NOS阳性神经元在生后第4天移植视网膜（TP4）中出现,TP12数量达到高峰值,TP22后降至正常成年鼠水平。结论 根据NOS阳性神经元的定位,分布,推测其为无长突细胞,移位无长突细胞及节细胞。