中国林蛙胸腺类肌细胞的细胞学研究

目的通过对中国林蛙胸腺的组织细胞结构研究,探讨胸腺类肌细胞的结构特点及年周变化规律。方法选用崂山产中国林蛙(Rana chensinensis),雌雄兼有,逐月取材,应用H-E、铅苏木精、Grimelius嗜银和PAS等染色方法进行染色,超微结构用日立透射电子显微镜进行观察。结果类肌细胞是中国林蛙胸腺髓质中恒定出现的一种特征性细胞。细胞质包含许多类似于骨骼肌内的典型结构——肌纤维,根据结构特点可将细胞分为未成熟、成熟以及退化3种类型。肌细胞的出现伴有明显的年周变化,2、3月份开始逐渐增多,到9月份肌细胞的大小与数量达到最大,不同月份所含细胞类型也大有不同。结论类肌细胞是胸腺实质组织中的一种正常细胞,具有不同发育阶段的3种形态结构类型,细胞数量和类型具有年周变化特点,推测与胸腺的正常功能有密切关系。     

Low Dietary Selenium Induce Increased Apoptotic Thymic Cells and Alter Peripheral Blood T Cell Subsets in Chicken

The purpose of this 42-day study was to investigate the effects of low selenium (Se) on immune function by determining histopathological changes of thymus, apoptosis of thymic cells, and subpopulation of peripheral blood T cells. One hundred twenty 1-day-old avian broilers were randomly assigned to two groups of 60 each and were fed on a low Se diet (0.0342 mg/kg Se) or a control diet (0.2 mg/kg Se), respectively. The relative weight of thymus was significantly decreased in low Se group from 21 days of age in time-dependent manner when compared with that of control group. Histopathologically, lymphopenia in the cortex and medulla of thymus was observed in low Se group. In comparison with those of control group, the percentage of Annexin-V positive cells was increased, and the percentages of CD3⁺ and CD3⁺CD8⁺ T cells of the peripheral blood were decreased in low Se group, as measured by flow cytometry. These data suggested that low dietary Se induced histological lesions of thymus, increased apoptosis of thymic cells, and decreased T cell subsets. The cellular immune function was finally impaired in broilers.     

Ontogeny of T Cells in the Pig Fetus

Mononuclear cells isolated from thymus, spleen and cord blood of pig fetuses ranging in age from 48 to 112 days were examined for the presence of sheep red blood cell rosette-forming cells (SRBC-RFC). After an initial increase from 77 % (mean) at 48 days of gestation to 88 % at 60 days, the proportion of SRBC-RFC in thymus remained constant throughout the gestational period. In spleen and cord blood, the proportion of SRBC-RFC increased with age, from occasional rosette-forming cells at 48 days of gestation to 21 % and 30 %, respectively, at 112 days. The demonstrated development of SRBC-RFC in the thymus, spleen and cord blood is considered to reflect the ontogeny of T cells in these fetal pig tissues.     

Sertoli Cells Maintain Leydig Cell Number and Peritubular Myoid Cell Activity in the Adult Mouse Testis

The Sertoli cells are critical regulators of testis differentiation and development. In the adult, however, their known function is restricted largely to maintenance of spermatogenesis. To determine whether the Sertoli cells regulate other aspects of adult testis biology we have used a novel transgenic mouse model in which Amh-Cre induces expression of the receptor for Diphtheria toxin (iDTR) specifically within Sertoli cells. This causes controlled, cell-specific and acute ablation of the Sertoli cell population in the adult animal following Diphtheria toxin injection. Results show that Sertoli cell ablation leads to rapid loss of all germ cell populations. In addition, adult Leydig cell numbers decline by 75% with the remaining cells concentrated around the rete and in the sub-capsular region. In the absence of Sertoli cells, peritubular myoid cell activity is reduced but the cells retain an ability to exclude immune cells from the seminiferous tubules. These data demonstrate that, in addition to support of spermatogenesis, Sertoli cells are required in the adult testis both for retention of the normal adult Leydig cell population and for support of normal peritubular myoid cell function. This has implications for our understanding of male reproductive disorders and wider androgen-related conditions affecting male health.     

Ontogeny of the Solitary Chemosensory Cells in the Zebrafish, Danio rerio

Secondary epidermal solitary chemosensory cells (SCCs) are widespreadamong the primary aquatic vertebrates. They resemble taste budsensory cells in fine structure and may be innervated from facialor spinal nerves. According to previous studies, SCCs may constitutea water sampling system in the contexts of predator avoidance,habitat recognition and, in some cases, finding food. By quantitativescanning (SEM) and transmission electron microscopy (TEM) in60 specimens (57 SEM, 3 TEM) of 16 developmental stages, frompre-hatchlings to adults, we describe the ontogenetic developmentof SCC densities and shapes of sensory apices in the zebrafish,Danio rerio. This is put into perspective with the ontogenyof external taste buds. Just prior to hatching, 3 days afterfertilization (3d AF), sensory apices of SCCs penetrate betweenthe squamous epidermal cells, whereas taste bud pores only appearat the onset of exogenous feeding (5d AF). SCC densities increasesharply from hatching shortly after metamorphosis (25d AF) upto 6 x 10³ per mm² on the head and remain relatively constantin density thereafter. Conservatively estimated, there may be     

鸡胚细胞的微载体培养

国外有许多利用微载体培养各种贴壁细胞的报道。鸡胚细胞(CEF cells)是最早用于体外培养的细胞之一,用它可生产多种鸡的疫苗,如法氏囊、新城疫、马立克疫苗等。我国生产上多采用滚瓶法,近年来才有微载体法培养的探索。要进行细胞的大规模培养,转瓶是有效的模拟,可以模拟生物反应器培养的一些条件,为放大作准备。本文模拟生物反应器的培养条件,用500ml转瓶（装液200ml）研究了鸡胚细胞在徽栽体上巾壁和生长的规律,为放大培养作了准备。     

Troponin in Cultured Chicken Breast Muscle Cells

The onset of troponin accumulation and the localization of troponin in cultured chick embryo skeletal muscle cells were studied by means of indrect immunofluorescent microscopy. At 31 hr after plating, troponin components were detected in 54–62% of total mononucleated myogenic cells and in all myotubes as longitudial fibrous structures. ³H-thymidine incorporation stduy coupled with the immunofluorescent microscopy showed that mononucleated myogenic cells at the mitotic stage did not contain troponin. As myotube maturation proceeds, the troponin-containing fibers were organized into cross-striated structures. At the myotube stage, muscle cells were labeled with ³⁵S-methionine and proteins synthesized were analyzed by two-dimensional gel electrophoresis. It was found that myotubes in culture synthesized both fast and slow types of troponin-I and-C. Our results suggest that fast and slow types of troponin components are synthesized in cultured skeletal muscle cells before or at the early phase of myofibrillogenesis.     

Expression of Chicken Interleukin-2 in Insect Cells

Full-length chicken interleukin-2 (ChIL-2) protein was successfully expressed using the recombinant baculovirus/Sf9 insect cell system. The expressed protein was soluble and reached approximately 12 microg/ml. Similarly to native ChIL-2, baculovirus expressed ChIL-2 revealed two main bands corresponding to molecular masses of 22 and 20 kD as detected by SDS-PAGE and Western blot. Treatment of the expressed protein with N-endoglycosidase F for 2 h caused the complete disappearance of the 22 kD band, while the 20 kD band (which is close to the molecular weight predicted from the cloned cDNA sequence) remained unchanged. Together with results on native ChIL-2, it can be concluded that ChIL-2 is an N-glycosylated protein.     

Ultrastructural Study of Proplastid Ontogeny in Tobacco Mesophyll Cells in Vitro

Since the discovery of plastid DNA the continuity of plastids has well been established. It is known that in plant cultures a form of plastid can differentiate into others. However, only a little has been made in studing chloroplast dedifferentiation in vitro. In the work present here, we reported on ultrastructural changes of chloroplasts dedifferentiation and the proplastid origin in the mesophyll cells of cultured tobacco leaf explant. Fully expanded leaves of haploid tobacco (cv. Ge Xin No. 1) were cut into pieces of 5–6 mm width. These were inoculated on MS medium supplemented with 1 mg/L 2,4-D and 1 mg/l kinetin. The cultures were maintained at (30±2) ℃ and illuminatied by a bank of fluorescent lamps. For electronmicroseopic investigation, after 0, 1, 2, 3, 6 days of culture small leaf fragments were cut off along the cut edges of the explants. The samples were fixed and processed in the manner as described earlier. The sections were examined with a Hitachi HU-11A or a JEM-100CX electronmicroscope. Electronmicroscopic observation shows that the uncultured mesophyll cells are highly vacuolete, with a thin peripheral layer of cytoplasm in which a nucleus and some chloroplasts and other organelles are found in it. But these cells do not contain proplastids (Fig. l). In the explants cultured for 1 day there are no obviously changes in mesophyll cells, except a few cytoplasmic strands extend from periphery to central vacuole. At 2 days of culture quite obvious changes can be detected. A increase in the amount of cytoplasm becomes apparent and transvacuolar cytoplasmic strands grow up. Following cytoplasmic growth, the nucleus and chloroplasts move away from the peripheral cytoplasm and enter the central vacuolate zone (Fig. 2). At this stage some of mesophyll cells have completed the first cell division. After 3 days of culture numerous mesophyll cells have undergone several divisions and formed multicellular masses. In those subdivided cells a more important change of the chloroplasts is the occurrence of protrusions which we call proplastid buds. This phenomenon has also been named as chloroplast budding. According to observations on a large amount of sections chloroplast budding is a common phenomenon in the dedifferentiating mesophyll cells of tobacco leaf explants. Fig ure 3 exhibits a typical profile of a chloroplast with a proplastid bud. The proplastid buds observed are generally long-oval in shape and 1.0–2.5 μm long and about 0.5–0.7 μm thick. These dimensions agree with those of proplastids in meristematie cells. Inside of proplastids ribosomes and electron opaque areas containing DNA fibrils can be seen (Fig. 3). Near the proplastid buds proplastids can often be found (Fig.5). According to above observations we can conclude that the proplastids in dedifferentiating mesophyll cells originate from the proplastid buds by chloroplast budding. The newly formed proplastids usually surround the nucleus and sometimes undergo equal division to increase their number (Figs.5, 6). There are no inner membranes in the newly formed proplastids except vesicles connected with inner membrane of the envelope (Fig.7). While the proplastids are continuously produced, the chloroplasts themselves are filled with starch and gradually turned to large amyloplasts (Fig.5). On the other hand, a few of chloroplasts can divide into equal parts following the chloroplast budding (Fig.4). Israel and Steward (1967) suggested that when cultured carrot cells developed into plantlets the chloroplasts turned into leucoplastids, chromoplastids or proplastids. However, they did not describe how chloroplast became a proplastid. Several investigators reported that the chloroplasts in the dedifferentiating cells gradually lost their grana and intergranal lamellae and then became eueoplasts or proplastids. But according to our observation in tobacco explants, the initiation of proplastids is due to unequal division of chloroplasts, i.e. “budding fission” as described by Malzan and Miihlethaler in Splachnum ampullaceum. Since the proplastid is an organelle characteristic of meristematie cells, the ontogeny of proplastids and its control mechanism should be very important in studing cell dedifferentiation.     

Requirement of Stat3 Signaling in the Postnatal Development of Thymic Medullary Epithelial Cells

Thymic medullary regions are formed in neonatal mice as islet-like structures, which increase in size over time and eventually fuse a few weeks after birth into a continuous structure. The development of medullary thymic epithelial cells (TEC) is dependent on NF-κB associated signaling though other signaling pathways may contribute. Here, we demonstrate that Stat3-mediated signals determine medullary TEC cellularity, architectural organization and hence the size of the medulla. Deleting Stat3 expression selectively in thymic epithelia precludes the postnatal enlargement of the medulla retaining a neonatal architecture of small separate medullary islets. In contrast, loss of Stat3 expression in cortical TEC neither affects the cellularity or organization of the epithelia. Activation of Stat3 is mainly positioned downstream of EGF-R as its ablation in TEC phenocopies the loss of Stat3 expression in these cells. These results indicate that Stat3 meditated signal via EGF-R is required for the postnatal development of thymic medullary regions.     

Intercellular Protein Transfer from Thymocytes to Thymic Epithelial Cells

Promiscuous expression of tissue restricted antigens (TRAs) in medullary thymic epithelial cells (mTECs) is crucial for negative selection of self-reactive T cells to establish central tolerance. Intercellular transfer of self-peptide-MHC complexes from mTECs to thymic dendritic cells (DCs) allows DCs to acquire TRAs, which in turn contributes to negative selection and regulatory T cell generation. However, mTECs are unlikely to express all TRAs, such as immunoglobulins generated only in B cells after somatic recombination, hyper-mutation, or class-switches. We report here that both mTECs and cortical TECs can efficiently acquire not only cell surface but also intracellular proteins from thymocytes. This reveals a previously unappreciated intercellular sharing of molecules from thymocytes to TECs, which may broaden the TRA inventory in mTECs for establishing a full spectrum of central tolerance.     

Xenotransplantation of Human Stem Cells into the Chicken Embryo

The chicken embryo is a classical animal model for studying normal embryonic and fetal development and for xenotransplantation experiments to study the behavior of cells in a standardized in vivo environment. The main advantages of the chicken embryo include low cost, high accessibility, ease of surgical manipulation and lack of a fully developed immune system. Xenotransplantation into chicken embryos can provide valuable information about cell proliferation, differentiation and behavior, the responses of cells to signals in defined embryonic tissue niches, and tumorigenic potential. Transplanting cells into chicken embryos can also be a step towards transplantation experiments in other animal models. Recently the chicken embryo has been used to evaluate the neurogenic potential of human stem and progenitor cells following implantation into neural anlage^1-6. In this video we document the entire procedure for transplanting human stem cells into the developing central nervous system of the chicken embryo. The procedure starts with incubation of fertilized eggs until embryos of the desired age have developed. The eggshell is then opened, and the embryo contrasted by injecting dye between the embryo and the yolk. Small lesions are made in the neural tube using microsurgery, creating a regenerative site for cell deposition that promotes subsequent integration into the host tissue. We demonstrate injections of human stem cells into such lesions made in the part of the neural tube that forms the hindbrain and the spinal cord, and into the lumen of the part of the neural tube that forms the brain. Systemic injections into extraembryonic veins and arteries are also demonstrated as an alternative way to deliver cells to vascularized tissues including the central nervous system. Finally we show how to remove the embryo from the egg after several days of further development and how to dissect the spinal cord free for subsequent physiological, histological or biochemical analyses.     

Appearence of LH-Immunoreactive Cells in the Rathke's Pouch of the Chicken Embryo

The differentiation of the pituitary of the chicken embryo was studied by means of an immunohistochemical technique using antisera to turkey and chicken pituitary hormones. Immunoreactive LH-cells are detected in 4-day embryos (stage 23 of Hamburger and Hamilton) when the primordium of the anterior pituitary, the Rathke's pouch is only composed of a single-layer epithelium lined with an undifferentiated mesenchyme. A few immunoreactive cells are observed grouped on the posterior aspect of the pouch. As development proceeds, a strip of positive cells is detected encircling the Rathke's pouch. Prolactin-, growth hormone-, and ACTH-immunoreactive cells are detected in 6- and 7-day embryos, only after the pituitary has acquired its characteristic structure with cords in which different cell types become progressively recognizable. The early appearance of immunoreactive LH-cells following a precise distribution shows that secretory properties and differentiation capacities are acquired simultaneously in the epithelium of the Rathke's pouch and may be induced by the same stimulus.     

人胎气管内胰岛淀粉样多肽免疫反应细胞的个体发生(英文)

为了进一步探讨胰岛淀粉样多肽（ＩＡＰＰ）的分布、定位以及它与其他生物活性物质的关系;用ＩＡＰＰ组织化学ＰＡＰ邻片双标法,观察了１８例１４～３８周人胎气管内ＩＡＰＰ免疫反应（ＩＲ）细胞的个体发生及与５羟色胺（５－ＨＴ）的关系。结果显示,胎１４周,气管粘膜表面的假复层柱状上皮中已有ＩＡＰＰ－ＩＲ细胞（Ｆｉｇ．１＆２）;１５周开始,粘膜固有层气管腺导管上皮中也出现分散的ＩＡＰＰ－ＩＲ细胞（Ｆｉｇ．３）;随胎龄增长,１７～２１周,气管上皮内ＩＡＰＰ－ＩＲ细胞逐渐增多;免疫染色加深（Ｆｉｇ．４＆５）,有些细胞发出细突直达腔面（Ｆｉｇ．６＆７）,粘膜下层的气管腺腺泡中也有ＩＡＰＰ－ＩＲ（Ｆｉｇ．８）; ２２～３８周,气管内 ＩＡＰＰ－ＩＲ 细胞又呈逐渐减少趋势,ＩＡＰＰ－ＩＲ仅出现在基底锥形细胞中（Ｆｉｇ．９＆１０）,且免疫染色较深。邻片未显５－ＨＴ－ＩＲ。本研究表明,人胎儿期气管上皮细胞内有ＩＡＰＰ的表达;且ＩＡＰＰ－ＩＲ细胞随胎期的发育而发生变化。     

蛇胸腺肌样细胞呈CRF和Mot免疫反应阳性

蛇胸腺肌样细胞呈ＣＲＦ和Ｍｏｔ免疫反应阳性陆宇燕李丕鹏（烟台师范学院生物系烟台２６４０２５）关键词蛇胸腺ＣＲＦＭｏｔ胸腺微环境在Ｔ细胞发育分化过程中起着重要的作用,因此研究胸腺基质细胞的生物学特性已成为免疫生物学的又一热点。胸腺微环境结构复杂,基质...     

鸡胚胎原始生殖细胞体外培养

以14-15期鸡胚血液为材料,采用Ficoll密度梯度离心方法,提取鸡胚胎原始生殖细胞(primordial germ cells,PGCs),在无基质细胞和基质细胞上分别进行体外培养。从实验结果可以看出：在含有胎牛血清(fetal bovine serum,FBS)、鸡血清(chicken serum,CS)、碱性成纤维细胞生长因子(bFGF)、人胰岛素样生长因子(hIGF-1)、小鼠白血病抑制因子(mLIF)和青,链霉素双抗的M199培养液中培养时,鸡PGCs最多能够存活4天：当采用细胞因子和5天鸡胚胎性腺基质细胞共培养时能存活23代且每代细胞增殖可达近10倍。提纯后的PGCs细胞冻存复苏后,经台盼蓝染色鉴定存活率可达80％左右。     

Ontogeny of Cell-Mediated Immunity of Murine Thymocytes and Spleen Cells

The ontogeny of cell-mediated immunity of spleen cells and thymocytes from B10 mice was studied in both in vitro mixed leukocyte culture and cell-mediated lympholysis reactions. Results show that newborn spleens contain cells competent to respond to X-irradiated allogeneic spleen cells in mixed leukocyte culture. The mixed leukocyte culture response of spleen cells, in terms of both index of stimulation and increment of tritiated thymidine incorporation, seems to be higher for mice four weeks or older than for mice less than four weeks old. The cell-mediated lympholysis response of spleen cells is not detectable until two days postpartum. It reaches adult levels in terms of % cytolysis by day four after birth. Thus, the transition period of the ontogeny of cell-mediated lympholysis response of spleen cells is apparently 0–4 days of age.
Newborn and early postnatal thymocytes (0–7 days of age) respond in mixed leukocyte culture at least as strongly as adult thymocytes (2–3 months of age). The cell-mediated lympholysis response of thymocytes is already detectable at birth, but weaker in terms of % cytolysis when compared with the cell-mediated lympholysis response of thymocytes from two days to six weeks of age. The cell-mediated lympholysis response of thymocytes starts to decline at 6–8 weeks of age. Thus, around the time of birth, there is a transition period in the cell-mediated lympholysis response of thymocytes during which thymocytes start to show high cell-mediated lympholysis reactivity. There is a second transition period between six and eight weeks of age during which the cell-mediated lympholysis response of thymocytes diminishes. The early, as well as late, postnatal cell-mediated lympholysis response of both spleen cells and thymocytes seems to be specific in nature.