男系断絶が皇統の断絶と同義であるという事は、女王を戴く英国人でさえ認識しています。

Japan's Chrysanthemum Throne claims to have the oldest line of succession of any monarchy,
with the first legendary emperor ascending to the title in 660BC.
That history is under threat of being snuffed out because of a dearth of male descendants in the royal family.

http://www.guardian.co.uk/international/story/0,,1647566,00.html