Embryology · Nervous system and senses
Pituitary gland: Rathke pouch and the neurohypophysis !
- Embryonic structure
The pituitary is built from two pieces: one that grows up from the roof of the mouth and one that grows down from the brain.
Updated 2026-11-01
See it in 3D: Pituitary gland · Hypothalamus · Optic chiasm · Third ventricle
What it is
The pituitary has a dual origin: Rathke's pouch, an ectodermal outpocketing of the roof of the stomodeum, forms the adenohypophysis; the infundibulum, an extension of the diencephalon, forms the neurohypophysis. This explains why the anterior lobe is glandular and the posterior lobe is nervous tissue, and why pouch remnants can give rise to a craniopharyngioma.
Key facts
- Week 3: Rathke's pouch appears in the roof of the stomodeum, in front of the oropharyngeal membrane.
- The pouch grows toward the infundibulum, which grows down from the floor of the diencephalon.
- End of the second month: the pouch loses its connection with the oral cavity.
- Anterior wall of the pouch → anterior lobe and pars tuberalis; posterior wall → pars intermedia.
- The infundibulum forms the stalk and posterior lobe, with glia (pituicytes) and axons from the hypothalamus.
- Remnants of the pouch stalk can persist in the pharyngeal roof or the sphenoid.
Structure
- Adenohypophysis: oral ectodermal epithelium (Rathke's pouch).
- Neurohypophysis: neuroectoderm of the diencephalon (infundibulum).
- The transcription factors HESX1, PROP1 and PIT1 specify the cell lines of the anterior lobe.
What it becomes
- Pars distalis (anterior lobe): GH, prolactin, TSH, ACTH, FSH and LH.
- Pars intermedia: rudimentary in humans.
- Pars tuberalis: wraps the stalk.
- Pars nervosa (posterior lobe): releases ADH and oxytocin made in the hypothalamus.
- Pouch remnants: a possible source of craniopharyngioma.
Markers
- HESX1
- PROP1
- POU1F1 (PIT1)
- LHX3
- SOX2
Clinical notes
- Craniopharyngioma: a tumor of Rathke's pouch remnants, often calcified; it compresses the chiasm (bitemporal hemianopia) and causes hormone deficits and diabetes insipidus.
- Septo-optic dysplasia: optic nerve hypoplasia, pituitary deficiency (mainly GH) and midline defects; linked to HESX1.
- Congenital hypopituitarism: neonatal hypoglycemia, prolonged jaundice, micropenis, short stature.
- Holoprosencephaly: pituitary dysfunction, particularly diabetes insipidus.
Test yourself
Think of the answer, then tap the question to see it.
Which embryonic structure does the anterior pituitary come from?
Rathke's pouch, an outpocketing of the ectoderm of the stomodeal roof.
Which tumor arises from Rathke's pouch remnants, and what visual defect does it cause?
Craniopharyngioma; by compressing the optic chiasm it causes bitemporal hemianopia.
Which syndrome combines optic nerve hypoplasia with pituitary deficiency?
Septo-optic dysplasia, linked in some cases to HESX1 variants.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Brain vesicles: from three to five and what each becomes
- The pharyngeal apparatus: arches, pouches, clefts and membranes
- Holoprosencephaly
- Eye: optic vesicle, optic cup and lens
- Adrenal gland: cortex from mesoderm, medulla from neural crest
Related conditions
- Hypopituitarism (incl. Sheehan syndrome and pituitary apoplexy)
- Diabetes insipidus (central and nephrogenic)
- Prolactinoma (hyperprolactinaemia)
- Acromegaly and gigantism
Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.
Sources: Septo-optic dysplasia: MedlinePlus Genetics (U.S. National Library of Medicine, 2024); Nonsyndromic holoprosencephaly: MedlinePlus Genetics (U.S. National Library of Medicine, 2024); Langman's Medical Embryology, 13th ed., ch. 18: Central Nervous System (Wolters Kluwer, 2015).
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Representative model, for educational purposes only.