restriction. n. 1. something that restricts; a restrictive measure, law, etc. 2. the act of restricting or the state of being restricted. 3. (Logic) logic maths a condition that imposes a constraint on the possible values of a variable or on the domain of arguments of a function.
The primitive gut that forms during gastrulation in the developing embryo is known as the archenteron or the digestive tube.It develops into the digestive tract of an animal.ach is controlled by the dorsal blastopore, and primitive node (also known as Hensen's node), respectively. During Gastrulation, the Archenteron develops into the digestive tube, with the blastopore developing into either the mouth (Protostome) or the anus (Deuterostome).
The primitive streak is a structure that forms in the blastula during the early stages of avian, reptilian and mammalian embryonic development.The presence of the primitive streak will establish bilateral symmetry, determine the site of gastrulation and initiate germ layer formation.he formation of the primitive streak in the blastocyst involves the coordinated movement and re-arrangement of cells in the epiblast. Even before the streak is visible, epiblast cells have started to move. Two counter-rotating flows of cells meet at the posterior end, where the streak forms.