"Sections through the unilaminar (A), bilaminar (B), and trilaminar (C) conditions of the typical biastoder. Ect., ectoderm; Ent., entoderm; Mes., mesoderm; c, primitive connective tissue." — Encyclopedia Britannica, 1893

Unilaminar

"Sections through the unilaminar (A), bilaminar (B), and trilaminar (C) conditions of the typical biastoder.…