By 1931, however, means of studying the "string" in some detail was provided by newly developed methods of examining the ten chromosomes of the maize complement in microsporocytes at the pachytene stage of meiosis.    From Wordnik.com.  [Nobel Lecture The Significance of Responses of the Genome to Challenge] Reference

Each chromosome is identifiable by its relative length, by the location of its centromere, which is readily observed at the pachytene stage, and by the individuality of the chromomeres strung along the length of each chromosome.    From Wordnik.com.  [Nobel Lecture The Significance of Responses of the Genome to Challenge] Reference