彼は源氏の嫡流を受け継ぐ家柄の出身だ。
He comes from a family in the direct line of the Minamoto clan.
嫡流が途絶えたため、分家から養子を迎えた。
Since the main line had died out, they adopted an heir from a branch family.
この家は藤原氏の嫡流を名乗っている。
This family claims to be the direct line of the Fujiwara clan.