THE KINETOCHORE OR SPINDLE FIBRE LOCUS IN AMPHIUMA TRIDACTYLUM

¹ From the Department of Zoölogy, Columbia University, New York City

1. The kinetochore is a compound body composed of a commissural region and a spindle spherule, so far as univalent chromosomes are concerned.

2. The half spindle component connects with the chromosome through the spindle spherule.

3. Already during the diakinetic phases of meiosis, each tetrad has two kinetochores which are distinct and separate from each other. Each of these is provided with two spindle spherules, so that each tetrad carries a total of four spindle spherules.

4. In the first spermatocyte division, the kinetochores lead the way to the poles. The dyads resulting from this division each show two spindle spherules until the resting stage is reached.

5. At metaphase of the second spermatocyte, each dyad is already sharply differentiated into two chromatids or univalent chromosomes. Each of these carries a kinetochore provided with a spindle spherule.

6. Aside from its structure, various staining reactions mark the kinetochore as an organ quite distinct from the ordinary chromomere.

7. The possible relation of the kinetochore to cell mechanics is discussed, and certain cytogenetic aspects are considered.

This article has been cited by other articles:

				A. T. L. Chen and A. Falek Centromeres in Human Meiotic Chromosomes Science, November 21, 1969; 166(3908): 1008 - 1010. [Abstract] [PDF]