Abstract
While an enormous amount of research has been carried out on the permeability of the external cell membrane, very little consideration has been given to the permeability of the nuclear membrane. In fact, only one paper, that of Monne 1 on diffusion of microinjected dyes from cytoplasm to nucleus, has come to our attention.
A few preliminary experiments, carried out at the end of the past season at Woods Hole, indicate the possibility of making quantitative and extended studies on the permeability to water of the nuclear membrane in permanently immature eggs of the starfish, Asterias forbesii. The great advantage of this cell over others. examined is that the nucleus is of a size sufficient to make possible fairly accurate measurements of its diameter with high dry magnification and the filar ocular micrometer. In the mature starfish egg the nucleus is of much smaller size than in the immature egg. Some of the eggs in every lot remain permanently immature and with care in selection immature eggs almost spherical in shape and with a spherical germinal vesicle may be secured.
Measurements of the swelling and shrinking of each egg were conducted separately. The egg was isolated, transferred to sea water diluted to the desired degree, and placed with a quantity of the diluted sea water in a small, closed glass chamber with optically plane faces. The temperature was about 21°C. but was not controlled. Measurements on cell and nucleus diameters were started as soon as possible after transfer to the diluted sea water, and were continued until both cell and nucleus reached an equilibrium volume, whereupon the egg was returned to 100% sea water and a new set of measurements made.
Get full access to this article
View all access options for this article.