Embryonic development of endoderm in chicken (Gallus gallus domesticus)

The poultry industry is a sector of agribusiness which represents an important role in the country's agricultural exports. Therefore, the study about embryogenesis of the domestic chicken (Gallus gallus domesticus) has a great economic importance. The aim of this study was to evaluate embryonic development of the endoderm in chicken (Gallus gallus domesticus). Forty fertilized eggs of domestic chickens, starting from the 1st day of gestation and so on until the 19 days of the incubation were collected from the Granja São José (Amparo, SP, Brazil). Embryos and fetus were fixed in 10% formaldehyde solution, identified, weighed, measured, and subjected to light and scanning electron microscopy. The endoderm originates the internal lining epithelium of the digestive, immune, respiratory systems, and the organs can be visualized from the second day (48 h) when the liver is formed. The formation of the digestive system was complete in the 12th day. Respiratory system organs begin at the fourth day as a disorganized tissue and undifferentiated. Their complete differentiation was observed at the 10 days of incubation, however, until the 19 days the syrinx was not observed. The formation of immune system at 10th day was observed with observation of the spleen, thymus, and cloacal bursa. The study of the organogenesis of the chicken based on germ layers is very complex and underexplored, and the study of chicken embryology is very important due the economic importance and growth of the use of this animal model studies such as genetic studies. Microsc. Res. Tech. 76:803–810, 2013. © 2013 Wiley Periodicals, Inc.     

A histological and immunohistochemical study on the parabronchial epithelium of the domestic fowl's (Gallus gallus domesticus) lung with special reference to its scanning and transmission electron microscopic characteristics

The current study was designed to give complete histo-and immunohistochemical features of the parabronchial epithelium of domestic fowl's (Gallus gallus domesticus) lung with special reference to Scanning electron microscope (SEM) and mean transmission electron microscope (TEM) features. The lung exhibited variable-sized atrial openings encircled by exchange tissue zones. The parabronchial atrial chambers appeared as ovoid and polygonal-shaped that separated by the well-developed interatrial septum. The deep atrial lumens had blood vessels pierced by openings that represent the infundibula. The parabronchial blood capillaries meshwork was branched and exhibited ovoid-shaped air capillaries with numerous extravasated blood vessels. By TEM, there were several air capillaries and groups of squamous and endothelial respiratory cells and the squamous cells had oval nucleus with evenly distributed chromatin. The endothelial respiratory cells had few microvilli on their free surfaces. The parabronchial tubes opened into a group of widened atria that had smooth muscle bundles at the interatrial septa. The atrial chambers led to narrow infundibula. Moreover, the lining epithelium of parabronchi, atria, infundibula, and air capillaries was formed by simple squamous epithelium. Air capillary walls were lined by two types of respiratory cells (Types-I and II). Collagen fibers were concentrated within the tunica externa layers of the parabronchial blood vessels as well as, they were observed in CT interparabronchial septa. Immunohistochemically, the elastin immunoreactivity was detected around the parabronchial blood vessels, at the base of each parabronchial atria, and in the area encircling the alveolar-capillary walls. Our work concluded that there are a relation between the fowl's lifestyle and the surrounding environmental conditions.     

Spatial and functional relationships between air conduits and blood capillaries in the pulmonary gas exchange tissue of adult and developing chickens

The documented data regarding the three-dimensional structure of the air capillaries (ACs), the ultimate sites of gas exchange in the avian lung is contradictory. Further, the mode of gas exchange, described as cross-current has not been clearly elucidated. We studied the temporal and spatial arrangement of the terminal air conduits of the chicken lung and their relationship with the blood capillaries (BCs) in embryos as well as the definitive architecture in adults. Several visualization techniques that included corrosion casting, light microscopy as well as scanning and transmission electron microscopy were used. Two to six infundibulae extend from each atrium and give rise to numerous ACs that spread centrifugally. Majority of the ACs are tubular structures that give off branches, which anastomose with their neighboring cognates. Some ACs have globular shapes and a few are blind-ending tapering tubes. During inauguration, the luminal aspects of the ACs are characterized by numerous microvillus-like microplicae, which are formed during the complex processes of cell attenuation and canalization of the ACs. The parabronchial exchange BCs, initially inaugurated as disorganized meshworks, are reoriented via pillar formation to lie predominantly orthogonal to the long axes of the ACs. The remodeling of the retiform meshworks by intussusceptive angiogenesis essentially accomplishes a cross-current system at the gas exchange interface in the adults, where BCs form ring-like patterns around the ACs, thus establishing a cross-current system. Our findings clarify the mode of gas exchange in the parabronchial mantle and illuminate the basis for the functional efficiency of the avian lung.     

Morphogenesis of the different types of photoreceptors of the chicken (Gallus domesticus) retina and the effect of amblyopia in neonatal chicken

Despite the great variety in chicken photoreceptors, existing morphogenetic studies only deal with two types: rods and cones. We have therefore examined by scanning electron microscopy the first appearance and maturation of different retinal photoreceptors in 36 chicken embryos (Gallus domesticus), aged 5-19 days prehatching. On day 5 of incubation, chicken retinae were only composed of proliferating ventricular cells devoid of photoreceptors. On day 8, outer mitotic cells were separated from inner differentiating photoreceptors, by the transient layer of Chievitz. Ball-like protrusions appeared at the ventricular surface, representing the first signs of photoreceptor inner segment formation. From day 10 onward, double cones, single cones, and rods could be clearly distinguished, and occasional cilia were detected at their tip. On day 12, inner segments had increased in length and diameter, and frequently carried a cilium representing the beginning of outer segment formation. On day 14, most photoreceptors displayed a distinct outer segment. On day 19, photoreceptors had essentially assumed adult morphology. Based on the shape of their outer segments, two subtypes of cones and three subtypes of double cones could be distinguished. Throughout development, we observed microvilli close to maturing photoreceptors, either originating from their lateral sides, from their tip, or from Müller cells. Microvillus density peaked between day 12 and 14, indicating an important role in photoreceptor morphogenesis. Unilateral occlusion of the eyes of posthatching chicken reduced the proportion of double cones to single cones in the retina, indicating dependence of retinal morphogenesis upon functional activity of visual cells.     

Circadian organization and the role of the pineal in birds

All organisms exhibit significant daily rhythms in a myriad of functions from molecular levels to the level of the whole organism. Significantly, most of these rhythms will persist under constant conditions, showing that they are driven by an internal circadian clock. In birds the circadian system is composed of several interacting sites, each of which may contain a circadian clock. These sites include the pineal organ, the suprachiasmatic nucleus (SCN) of the hypothalamus, and, in some species, the eyes. Light is the most powerful entraining stimulus for circadian rhythms and, in birds, light can affect the system via three different pathways: the eyes, the pineal, and extraretinal photoreceptors located in the deep brain. Circadian pacemakers in the pineal and in the eyes of some avian species communicate with the hypothalamic pacemakers via the rhythmic synthesis and release of the hormone melatonin. Often the hypothalamic pacemakers are unable to sustain persistent rhythmicity in constant conditions in the absence of periodic melatonin input from the pineal (or eyes). It has also been proposed that pineal pacemakers may be unable to sustain rhythmicity in constant conditions without periodic neural input from the SCN. Significant variation can occur among birds in the relative roles that the pineal, the SCN, and the eyes play within the circadian system; for example, in the house sparrow pacemakers in the pineal play the predominant role, in the pigeon circadian pacemakers in both the pineal and eyes play a significant role, and in Japanese quail ocular pacemakers play the predominant role.     

ANSYS有限元分析二次开发技术探讨

运用UIDL和APDL语言,ANSYS中对一个长方体的有限元分析过程进行了二次开发,在软件中建立了专有菜单,实现了前处理、求解、后处理全过程的自动计算。ANSYS二次开发方法可应用于其他产品的有限元分析中,特别适合于简单几何模型及同类工况的有限元分析。二次开发后的ANSYS便于普通设计人员使用,避免了大量的重复性工作,提高了分析效率。     

VBA在图纸后处理中的开发及其应用

在工程设计过程中,诸如审图、明细表等图纸后处理工作占用了太多的时间和精力.结合多年的工程经验,利用Auto-CAD VBA二次开发技术,实现图纸质量和工作效率的双提高.     

AutoCAD二次开发中外部数据库使用方法研究

从AutoCAD二次开发入手,研究了外部数据库在AutoCAD二次开发中的应用,提出了通过配置外部数据库、创建连接、创建标签的基本方法,实现外部数据库在AutoCAD二次开发中的应用。     

UG二次开发中利用MFC的方法

介绍了UG二次开发工具和二次开发方法,重点阐述了UG二次开发中利用MFC的方法和步骤,并给出应用实例,方便了UG二次开发,扩展了UG二次开发的功能。     

图形变换在AutoCAD二次开发中的应用

通过实列介绍一种利用图形变换对AutoCAD进行二次开发的方法。     

基于UG二次开发的铣削参数优化仿真系统研究

对切削参数保守的选择严重制约了我国机床效率的发挥,文中通过利用UG的二次开发技术对基于UG的铣削参数优化仿真系统进行了研究,并且验证了系统的可行性。     

基于VisualC++的SolidWorks二次开发技术

本文介绍了应用可视化程序设计语言VisualC++6.0开发SolidWorks的基本原理,并通过实例论述了开发Solid Works的关键技术和方法。     

基于UG二次开发的谐波减速器的参数化设计

传统的谐波减速器的三维零件设计复杂,利用UG的二次开发可以提高UG的设计效率,缩短产品的设计周期.通过VC++编写优化算法程序,得到谐波齿轮减速器主要构件的三维参数数据.综合利用VC++和UG二次开发工具集,编写接口函数,实现谐波齿轮减速器的参数化设计,分别建立零件ACCESS数据库进行综合管理.并以减速器中最重要的构件柔轮的设计为例,说明UG二次开发的流程.     

UG二次开发技术在铣刀刀柄参数化设计中的应用

为了缩短产品设计周期、有效提高UG（UnigraphicsNX）平台的使用效率,文中介绍了一种利用UG的二次开发技术、Visual C＋＋、ACCESS相结合的形式实现铣刀刀柄参数化设计的一种方法。     

提高手机注塑模具设计开发效率的探讨

通过对当前公司注塑模具设计的调查分析,结合当前市场的需求,手机注塑模模具设计朝着高效,精密的方向不断地推进。手机的快速更替要求手机模具设计的设计周期必须进一步缩短。针对手机注塑模模具设计的特点,基于三维建模软件进行二次开发,针对性的开发适合本公司的软件,是整合当前的规范和经验、提高设计效率的必然途径。     

UG二次开发中MFC调用方法的研究

通过对UG／OPENAPI应用程序运行机理和开发流程的分析，深入介绍了如何真正在UG二次开发中调用MFC的实现方法，并奉例说明应用UG／OPENUlStyler，MenuScript，API实现对MFC的调用。     

基于Eplan二次开发的电气辅助设计工具集的设计与实现

对于DCS等规模较为庞大的仪控系统,在进行工程硬件设计时,工程设计软件的作用极为重要.Eplan软件作为成熟的计算机辅助工程软件,提供了二次开发接口便于用户根据实际需要进行针对性开发.本文基于Eplan软件在DCS电气设计过程中的应用,进行了软件的二次开发,针对提高设计过程中的便利性、容错性的目的,设计了一系列辅助设计...     

UG二次开发技术在虚拟装配干涉检验中的应用

为了缩短产品设计周期、有效提高UG(Un igraph ics NX)平台的使用效率,介绍了一种利用UG的二次开发技术与V isual C++相结合实现在UG虚拟装配模块中提高干涉检验效率的方法。     

Snout cutis of the domestic pig (Sus scrofa domesticus,Linnaeus, 1758): Using light and transmission electron microscopy

The current study was designed to give microscopic view on the snout skin of the domestic pig (Sus scrofa domesticus) to clear its adaptations with the function of exploring for the food and pushing the objects. This study carried out on the snout skin of apparently healthy 1 year five pigs (Sus Scrofa) and examined under the light and transmission electron microscopy. Our results clarify that the snout skin cutis composed of the epidermis and the dermis. The epidermis consisted of stratum corneum, stratum granulosum, stratum spinosum, and stratum basale. The stratum corneum and the stratum spinosum appeared thicker than other parts. The dermis consisted of a reticular and a papillary dermis. For tightness junction between the dermis and the epidermis, the hemidesmosomes were observed, while the desmosomes were presented in abundant numbers at the level of stratum basale to ensure the adhesion between the keratinocytes. The merocrine sweat glands were observed in abundant numbers to provide the wetness of the snout to avoid its injury from friction during food exploring or pushing of the objects. We concluded that the adaptation of the snout skin with the environmental condition surrounding the studied domestic pig.     

VERICUT 仿真技术在转向架制造领域的应用及二次开发

随着制造技术的不断提高,产品更新换代的周期越来越短,数控机床满足了越来越复杂的产品加工需求,随之而来的问题是如何保证数控机床试切的安全性,缩短产品的试制周期和试验费用,降低制造过程中的废品率,减少制造的工时成本,最大限度地提高数控设备的使用率。基于企业的上述需要,虚拟仿真加工技术成为数控加工前一个必不可少的重要环节。从长客股份公司转向架生产中典型大部件数控加工中存在的问题入手,结合VERICUT计算机辅助仿真技术,指出了在高速加工中进行加工虚拟仿真的必要性,并描述了VERICUT仿真软件在转向架制造领域的应用情况及效果。