Science. 2020 Oct 23;370(6515):463-467. doi: 10.1126/science.aba4767. PMID: 33093109
These researchers used lineage tracing, combined time-lapse imaging with single cell RNA sequencing in zebrafish, and identified that endoderm actually also contributes to the formation of adenohypophysis primordium and resultant pituitary.
The pituitary gland is considered to be formed from an evagination of neural ectoderm that forms the posterior lobe and an invagination of oral ectoderm called Rathkes pouch, which gives rise to the anterior and intermediate lobes. Furthermore, endoderm can generate a rudimentary adenohypophysis-like structure in the near absence of ectodermal contributions. It would be interesting to see whether the endoderm also participates in the pituitary formation in other vertebrates, and if there is any extensive interchange-ability of ectodermal and endodermal epithelia in generating diverse cranial organs.