A study of the inductive capacity of post-nodal primitive-streak pieces after treatment with follicle-stimulating hormone.

Chick embryos at the primitive-streak stage were treatedin vitro with 0.002 and 0.008% follicle-stimulating hormone (FSH)(NIH-FSH-S1) for 24 hours. Post-nodal primitive-streak pieces 0.8 mm behind the node level were grafted into host chick embryos at the primitive-streak stage to assess the capacity of the grafted pieces to produce inductions.Control grafts from donors maintained under identical conditions were unable to cause induction; all of them were resorbed into the host embryo. The post-nodal pieces treated with FSH acquired capacity to induce neural tissue. The grafts seemed to induce foregut formation also. FSH appeared to have supported differentiation of the grafts into somites and mesenchyme.