| TC | target cell; taurocholate; temperature compensation; teratocarcinoma; tertiary cleavage; tetracyclin... |
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| total cleavage | Cleavage in which the blastomeres are completely separated; the entire egg participates in cell division. Synonym: complete cleavage, total cleavage. (05 Mar 2000) |
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| enamel cleavage | The splitting of enamel in a plane parallel to the direction of the enamel rods. (05 Mar 2000) |
| equal cleavage | Cleavage producing blastomeres of like size. (05 Mar 2000) |
| equatorial cleavage | Cleavage in which the plane of cytoplasmic division is at right angles to the axis of the ovum. (05 Mar 2000) |
| yolk cleavage | Segmentation of the vitellus. (05 Mar 2000) |
| unequal cleavage | Cleavage producing blastomeres of different sizes at the two poles. (05 Mar 2000) |
| freeze cleavage | Method of specimen preparation for the electron microscope in which rapidly frozen tissue is cracked so as to produce a fracture plane through the specimen. The surface of the fracture plane is then shadowed by heavy metal vapour, strengthened by a carbon film and the underlying specimen is digested away, leaving a replica that can be picked up on a grid and examined in the transmission electron microscope. The great advantage of the method is that the fracture plane tends to pass along the centre of lipid bilayers and it is therefore possible to get en face views of membranes that reveal the pattern of Integral membrane proteins. The E face is the outer lamella of the plasma membrane viewed as if from within the cell, the P face the inner lamella viewed from outside the cell. Fracture planes also often pass along lines of weakness such as the interface between cytoplasm and membrane, so that outer and inner membrane surfaces can be viewed. Further information about the structure can be revealed by freeze etching. Extremely rapid freezing followed by deep etching has allowed the structure of the cytoplasm to be studied without the artefacts that might be introduced by fixation. (18 Nov 1997) |
| vestibular lip of limbus of spiral lamina | vestibular labium of limbus of spiral lamina |
| hamulus of spiral lamina | The upper hooklike termination of the bony spiral lamina at the apex of the cochlea. Synonym: hamulus laminae spiralis, hamulus cochleae, hook of spiral lamina. (05 Mar 2000) |
| proximal spiral septum | See: spiral septum. (05 Mar 2000) |
| secondary spiral lamina | A ridge on the outer wall of the first turn of the cochlea opposite the spiral lamina. Synonym: lamina spiralis secundaria, secondary spiral plate. (05 Mar 2000) |
| secondary spiral plate | A ridge on the outer wall of the first turn of the cochlea opposite the spiral lamina. Synonym: lamina spiralis secundaria, secondary spiral plate. (05 Mar 2000) |
| hook of spiral lamina | The upper hooklike termination of the bony spiral lamina at the apex of the cochlea. Synonym: hamulus laminae spiralis, hamulus cochleae, hook of spiral lamina. (05 Mar 2000) |
| spiral | Of leaves or floral organs, borne at different levels on the main stem, in an ascending spiral. Compare: cyclic. (09 Oct 1997) |
| spiral and curved bacteria | A large, very diverse group of bacteria in which some species are curved, some helical. (12 Dec 1998) |