Mesentery

Japanese: 間膜 - かんまく

…Except for a portion of the upper surface that is attached to the diaphragm, the surface is covered with the peritoneum (serosa), giving the liver a smooth and shiny appearance. The peritoneum that covers most of the liver surface is continuous with the peritoneum that lines the abdominal wall and covers other abdominal organs, so it forms folds (called mesenteries) in places on the liver surface that are free. The falciform mesentery, which runs vertically slightly to the right of the midline on the front of the liver, is attached at its lower end to the cord-like ligamentum teres hepatis, a remnant of the umbilical vein from the fetal period, and its upper end separates to the left and right on the upper surface of the liver, transitioning into the coronary mesentery, and then becoming the left and right intertriangular mesentery, which is then flipped over onto the underside of the diaphragm. …

From [serosa]

…The subserosal tissue is made up of thin, loose connective tissue and is rich in fibroblasts, free cells (lymphocytes, monocytes, histiocytes, etc.), blood vessels, lymphatic vessels, nerves, and adipose tissue. The area where the two serosal membranes meet is called the mesentery. Both sides of the mesentery are covered by serosal epithelium, which sandwiches the subserosal tissue between them. …

*Some of the terminology that mentions "mesenchyma" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…横隔膜と癒着している上面の一部を除いては，腹膜(漿膜)が表面を覆っているため，外観は平滑で光沢がある。　肝臓表面の大部分を覆っている腹膜は，腹壁を裏打ちし，他の腹腔諸臓器を覆う腹膜に連続しているため，肝臓表面のところどころでひだ(これを間膜という)となって遊離している。肝臓の前面で，正中線よりやや右寄りを縦走する肝鎌状間膜は，下端で胎生期の臍静脈が遺残した索状の肝円索に接着し，その上端は肝臓の上面で左右に離開し，冠状間膜へと移行し，さらに左右の三角間膜となって，横隔膜の下面へ翻転している。…