Spindle birefringence

Immediately, two problems are obvious in attempting to relate birefringence and microtubules. First, the birefringence must be preserved during preparation for electron microscopy. Spindle birefringence in some materials is said to be maintained by a modified fixation procedure (Inou and Sato, 1967), but the possible effect of later... 

Exploiting the fact that the spindle hbers are optically anisotropic, or birefringent, with different indices of refraction in different directions (i.e., parallel or perpendicular to the hber axis), Inoue (2) developed a sensitive polarized light microscope... 

Fig. 1. A living primary spermatocyte of Pardalophora apiculata (a grasshopper) as viewed in Inoue s rectified polarizing microscope. A., Metaphase kinetochores of one bivalent are indicated by arrows ("k ) and polar regions by p". Birefringent chromosomal spindle fibers run from each kinetochore toward a pole the diffuse background birefringence of interpolar fibers is identified only with difficulty In the prints but Is readily measured. B., Metaphase the opposite compensator setting. C, D. Anaphase 22 and 36 minutes, respectively, after A. XI,500.

Forer, A. 1965. Local reduction of spindle fiber birefringence in living Nephrotoma suturalis (Loew) spermatocytes induced by ultraviolet microbeam irradiation. J. Cell Biol., 25 (Mitosis Suppl.) 95-117. 

Sato, H. 1969. Analysis of the form birefringence in the mitotic spindle. Amer. Zool., 9 592 (abstr.). 

When the colloids just mentioned are sufficiently concentrated and their electro lyte content is not so high as to cause irregular flocculation, the sol separates into two phases a dilute isotropic and a more concentrated birefringent one. Under the microscope between crossed nicols one observes that the anisotropic phase forms spindle-shaped islands in the dilute phase. When the original sol is very concentrated the reverse phenomenon is observed, i.e., isotropic spindles are. formed in an anisotropic sol. The anisotropic spindles have been called tactoids by Freundlich Fig. 20 gives a fine... 

By one sided dark field illumination (Szegvari, Fig. 22) and also by determination of the sign of the birefringence it has been ascertained that in the spindles the rodlike particles are situated nearly parallel to the long axis of the spindle as shown schematically in Fig. 23 . 

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