Responsa for Bekhorot 77:67

חסרון מבפנים שמיה חסרון ומר סבר

Shall it therefore be said that this is the point at issue, that one Master hol that a deficiency inside the animal is considered a loss [which can disqualify], whereas the other Master holds that a deficiency inside the animal is not considered a deficiency [to disqualify]? - Said R'Hiyya B'Joseph: All [the authorities] agree that a living creature can be created with one kidney only, and the deficiency inside is considered a deficiency; and still there is no difficulty.<span class="x" onmousemove="('comment',' As regards a contradiction between the two Baraithas.');">³⁷</span>

Teshuvot Maharam

Teshuvot Maharam