Biomaterial Database

Correlated scanning and transmission electron microscopy of developing lens vesicle in the chick. 1979

J J Van Rybroek, and M D Olson

Cells within the lens placode undergo transient surface modifications during the course of invagination. At stage 13, cellular apices bulge outward and display decreased surface diameters when compared to adjacent surface ectoderm. The lens vesicle is well invaginated by stage 14. An area of modified cells can be recognized ventral to the lens vesicle aperture. These cells present a smaller surface area and increased pleomorphism. Normal surface ectoderm extends to the dorsal and lateral edges of the aperture. The apical surfaces of cells which line the lumen of the lens vesicle display a complex topography such that individual cell boundaries are not easily distinguished. At stage 17, cellular processes which partially occlude the closing aperture of the lens vesicle may assist in reestablishing ectoderm over the newly formed lens. Preliminary results of cytochalasin B exposure on the invaginating lens vesicle suggest that the contractile action of microfilaments influences the complex cellular topography.

UI	MeSH Term	Description	Entries
D007908	Lens, Crystalline	A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.	Eye Lens,Lens, Eye,Crystalline Lens
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D008855	Microscopy, Electron, Scanning	Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.	Scanning Electron Microscopy,Electron Scanning Microscopy,Electron Microscopies, Scanning,Electron Microscopy, Scanning,Electron Scanning Microscopies,Microscopies, Electron Scanning,Microscopies, Scanning Electron,Microscopy, Electron Scanning,Microscopy, Scanning Electron,Scanning Electron Microscopies,Scanning Microscopies, Electron,Scanning Microscopy, Electron
D002642	Chick Embryo	The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.	Embryo, Chick,Chick Embryos,Embryos, Chick
D004475	Ectoderm	The outer of the three germ layers of an embryo.	Apical Ectodermal Ridge,Apical Ectodermal Ridges,Ectodermal Ridge, Apical,Ectoderms
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia