Pharyngeal pituitary: development, malformation, and tumorigenesis

Area of Science:

• Developmental biology
• Endocrinology
• Neuroscience

Background:

• The pharyngeal pituitary (PhP) is a distinct pituitary structure whose developmental trajectory and functional significance remain incompletely understood.
• Previous research has primarily focused on the sellar pituitary (SP), leaving the PhP's embryogenesis and potential roles less explored.

Observation:

• Morphological and immunohistochemical analyses revealed that PhP begins hormone production at 17-18 weeks of gestation, significantly later than SP.
• A rare craniopharyngeal pituitary (CPhP) remnant was observed in one fetus, and ectopic pituitary adenomas often appear in locations corresponding to PhP.
• Systemic examination of fetuses with cranioneural malformations identified novel PhP malformations, including agenesis, fragmentation, and pharyngosellar pituitary formations.

Findings:

• PhP is consistently present across all examined fetuses, including anencephalic individuals, challenging previous assumptions about SP agenesis in anencephaly.
• Hormone production in malformed PhP tends to be delayed, suggesting developmental vulnerability.
• The consistent location of ectopic pituitary adenomas strongly implicates PhP as a potential origin, though CPhP cannot be entirely ruled out.

Implications:

• This study provides the first comprehensive description of PhP development and its associated malformations.
• Findings suggest PhP plays a crucial role in pituitary development and may be the origin of certain ectopic pituitary adenomas.
• The presence of PhP in anencephalic fetuses necessitates a re-evaluation of pituitary development in severe congenital brain malformations.