“The tip of the optic stalk is a considerable distance from the surface ectoderm.”

“The branchial arches begin as cylindrical cores of mesenchyme sandwiched between continuous sheets of epidermal ectoderm and internal endoderm.”

“The mouth and pharynx are derived by a secondary infolding of superficial ectoderm called the stomodeum.”

“During the last five hours of development followed here, the ectoblast begins to spread out over the macromeres.”

“This fold springs from the ectoblast or external series of cells in the embryo.”

“In each genus, some ectoblast tiers divide faster and others slower.”