Figure 3.
Diagram of a Dividing Plant Cell in Late Metaphase.
This figure depicts a system of Ca2+-containing endoplasmic reticulum that extends from the spindle poles to the chromosomes along kinetochore microtubules. It was suggested that during anaphase, Ca2+ release from the endoplasmic reticulum activates motile processes (e.g., microtubule depolymerization) and thus facilitates movement of the chromosomes to the spindle poles. In support of this model, Ca2+-stimulated depolymerization of microtubules and facilitation of chromosome motion have been observed (Zhang et al., 1992). Although an endogenous increase in [Ca2+]i during anaphase has been reported using the absorbance indicator arsenazo III (Hepler and Callaham, 1987), this has not been repeated with a more efficacious fluorescent dye. (Figure courtesy of Hepler et al., 1981, Figure 7, with kind permission of Springer Science and Business Media.)