Figure 1.

Deficiency of FREM2 and FRAS1 cause anterior sac hernias in mice. (A) A retrosternal diaphragmatic hernia in a FREM2-deficient Frem2^ne/ne mouse as viewed from the thorax. The herniated viscera are covered by a membranous sac (yellow outline). (B) A retrosternal diaphragmatic hernia (yellow arrow) in a Frem2^ne/ne mouse as viewed from the abdomen. (C, D) H&E-stained coronal sections through the hernial sac of a Frem2^ne/ne mouse reveal herniated liver tissue (Lv) and the gallbladder (G, red arrow) surrounded by a thin membranous sac. There is a rapid transition from the muscularized diaphragm (*) to a thin amuscular sac (blue arrow). (E) A retrosternal diaphragmatic hernia in a FRAS1-deficient Fras1^{Q1263*/Q1263*} mouse as viewed from the thorax. The herniated viscera are covered by a membranous sac (yellow outline). (F) The same retrosternal diaphragmatic hernia (yellow arrow) shown in (E) but viewed from the abdomen after reduction of the gallbladder and a pedunculated liver mass (Lv). D, diaphragm; St, sternum.