Fig. 5: Oocytes and eggs inside Xenoturbella bocki.

a MicroCT section showing immature oocytes as black spots present between the epidermis and the gut. b A group of oocytes present in a female. c Oocytes lined up in a near single row. d Mature egg found between the epidermis and the gut. e MicroCT section showing an oocyte in a pocket sinking within the gut. f Mature egg in a pocket sinking within the gut. g Mature egg that has almost sunk within the gastrodermal cells. h Mature egg that has sunk within the gastrodermal cells. The pocket is connected by a thin tunnel to the space between the epidermis and the gut. i A group of eggs present in a female. j The eggs in a group is divided by a thin layer into individual compartments. k Eggs lined up in a near single row in a female. l Volume rendering image from microCT scans showing five eggs within a female. The eggs are not in a complete single row. m MicroCT section showing empty pockets (black arrowheads) present in the gut. n Eggs present in the gut cavity. o A tunnel (white arrowhead) connecting the space between the epidermis and the gut and the gut cavity. Scale bars: a–e, g–i, k–o: 200 μm; f, j: 100 μm.