Bajer et al. 1961

Bajer A, Hansen-Melander E, Melander Y, Molè-Bajer J. 1961. Meiosis in Cepaea nemoralis studied by microcinematography. Chromosoma (Berl.) 12: 374-381.

These authors studied spermatogenesis in the helicid land snail Cepaea nemoralis, an hermaphrodite with accessible meiotic cells containing 28 bivalents. The stated aim of this paper is to contribute to knowledge of basic meiotic processes in animals, and compare them to meiosis in plants. This was accomplished through the use of an apparently cutting-edge-technology phase-contrast microscope, and for at least this paper, 16mm film.

Most of this paper is a description of the changes in shape and size of the nucleus of meiotic cells, and the movements of the chromosomes in the minutes immediately before and after the disappearance of the nuclear membrane. The nucleus is apparently somewhat unstable during prophase, changing position in the cell in a random fashion and changing shape rapidly. The chromosomes inside the intact nucleus also seem to move randomly, in a manner that does not suggest pulling by microtubules or other cytoskeletal components. Just prior to the disappearance of the nuclear membrane, the nucleus increases in size; this phenomenon is not explained even by speculation in this paper.

Previous work by these authors, using the same microscope, included measurements of nucleus mass by interference microscopy. How mass is measured is not clearly explained, but this paper is the first reference to this measurement I have seen.