Biomaterial Database

Cleavage in the chick embryo. 1978

R Bellairs, and F W Lorenz, and T Dunlap

Chick embryos ranging from the stage of first cleavage to that of about 700 cells were removed from the oviduct and examined by transmission electron microscopy. Beneath the cell membrane is yolk-free cortical region containing microfilaments. Beneath this lies cytoplasm which contains yolk spheres which are graded in size, the dorsal ones being smaller than the ventral ones. The subgerminal periblast possesses a greater proportion of yolk to cytoplasm than do the cells proper, but it merges with the cytoplasm at the incomplete borders of the 'open' cells. Specialized accumulations of membranes lie in the marginal periblast, and it is suggested that they play a role in cell membrane formation.

UI	MeSH Term	Description	Entries
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
D001755	Blastocyst	A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.	Embryo, Preimplantation,Blastocysts,Embryos, Preimplantation,Preimplantation Embryo,Preimplantation Embryos
D001756	Blastoderm	A layer of cells lining the fluid-filled cavity (blastocele) of a BLASTULA, usually developed from a fertilized insect, reptilian, or avian egg.	Blastoderms
D002455	Cell Division	The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.	M Phase,Cell Division Phase,Cell Divisions,Division Phase, Cell,Division, Cell,Divisions, Cell,M Phases,Phase, Cell Division,Phase, M,Phases, M
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D002466	Cell Nucleolus	Within most types of eukaryotic CELL NUCLEUS, a distinct region, not delimited by a membrane, in which some species of rRNA (RNA, RIBOSOMAL) are synthesized and assembled into ribonucleoprotein subunits of ribosomes. In the nucleolus rRNA is transcribed from a nucleolar organizer, i.e., a group of tandemly repeated chromosomal genes which encode rRNA and which are transcribed by RNA polymerase I. (Singleton & Sainsbury, Dictionary of Microbiology & Molecular Biology, 2d ed)	Plasmosome,Cell Nucleoli,Nucleoli, Cell,Nucleolus, Cell,Plasmosomes
D002467	Cell Nucleus	Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Cell Nuclei,Nuclei, Cell,Nucleus, Cell
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
D003593	Cytoplasm	The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)	Protoplasm,Cytoplasms,Protoplasms
D005260	Female		Females