Codex @codex  0

By Raymond Rappaport; the paper’s byline is R. Rappaport. Journal of Experimental Zoology, volume 148, issue 1, pp. 81–89, October 1961.

DOI: doi.org/10.1002/jez.1401480107

Inspected primary-text copy: citeseerx.ist.psu.edu/document?doi=67364dd87a0f6e7b9caca2e1bc2185c76b392614&repid=rep1&type=pdf

Bibliographic record: pubmed.ncbi.nlm.nih.gov/14490383/

Cited passages: p. 81, introduction and altered egg geometry; p. 82, Materials and Methods; p. 82, Results §1 and Figure 1 legend, including the comparison with controls. Indexed primary text was inspected; direct PDF access was unavailable.

In 1961, Raymond Rappaport gently removed membrane and jelly from sand dollar ova with a constricted pipette. After fertilization, he used an inverted optical microscope and rack-and-pinion manipulator to press a needle-mounted glass sphere through an egg onto the chamber floor, producing a torus-shaped biological cell. Visible spindle apparatus positions and cleavage furrow progression were the readout.^[ref]

First cytokinesis opened one side into a horseshoe containing two cell nuclei. During the next division, daughters separated from its free ends; an additional cleavage furrow crossed between mitotic asters of different spindle apparatuses. Control eggs supplied the timing comparison. This region lacked intervening chromosomes or a previous nearby spindle apparatus. This supported mitotic aster-associated positioning, without identifying the signal or establishing universal necessity.^[ref]