mitoses

The division of the generative cell, on the other hand, is obscured by the densely packed starch grains that have accumulated during the interval between the two mitoses.

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983

On the female side only a single cell in the kernel-to-be undergoes meiosis, and the embryo sac arises from only one of the four spores produced by the two meiotic mitoses.

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983

This cycle, initially detected at the first mitosis in a microspore, could now be followed in subsequent mitoses.

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983

When no telomere is present, attempts to replicate this uncapped end may be responsible for the apparent "fusions" of the replicated chromatids at the position of the previous break as well as for perpetuating the chromatid type of breakage-fusion-bridge cycle in successive mitoses.

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983

This one haploid cell, the megaspore, then undergoes three successive mitoses to form the embryo sac, or the female gametopyhte.

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983

Their modes of origin could be projected form the known behavior of broken ends of chromosomes in successive mitoses.

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983

Entrance of a newly ruptured end of a chromosome into the zygote is followed by the chromatid type of breakage-fusion-bridge cycle throughout mitoses in the developing plant.

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983

How would this newly broken end behave in subsequent mitoses?

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983

The following was noted: (1) In the majority of mitoses replication of the ring chromosome produced two chromatids that were completely free from each other and thus could separate without difficulty in the following anaphase.

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983

As mentioned earlier, this cycle continues during successive mitoses in the development of the endosperm.

Nobel Lecture The Significance of Responses of the Genome to Challenge 1983