Whilst it is the truth, new techniques were used from 1956, it is not the whole truth, others ignored their own pictures, that are still available today, which clearly show 23.
A quote from Robert Matthews, “For years biochemists refused to believe humans possess 23 pairs of chromosomes”. Why? “Because it contradicted the claims” of this “influential American zoologist”. So, “many ignored the evidence of their own eyes rather than challenge the great man”. "The problem was not so much that Painter had blundered, but that “scientists had preferred to bow to authority rather than believe the evidence of their own eyes. Checking photographs of chromosomes reprinted in textbooks, researchers later found that 23 pairs were clearly shown—and yet captions under the photographs declared the figure to be 24.”
We have had numerous dissusions where I point out that I rely on the numbers (the data) not the commentary that follows it. The above is a prime example, anyone who looks the pictures can count 23 pairs, but the commentary that follows it says 24.