OBJECTS: During ontogeny, part of Rathke's pouch, a physiologically superior pouching of the stomodeal ectoderm, may remain, forming the usual anomaly known as Rathke's cleft cyst. More rarely, however, the entire pouch (i.e., the craniopharyngeal canal) remains, resulting in transsphenoidal meningoencephalocele. This study is aimed to provide a better understanding of the pathogenesis. MATERIALS AND METHODS: We histologically evaluated the inferior protrusion of the putative hypophysial fossa in 35 embryonic and fetal heads, respectively (15 at 5-8 weeks and 20 at 12-16 weeks of gestation). RESULTS: In 3 of the 35 specimens, we observed a complete cleft originating from the adenohypophysis, passing through the sphenoid and connecting with the pharyngeal epithelium or pharyngobasilar fascia. In another 18 specimens, we observed a duct-like structure protruding from the fossa and ending in the sphenoid. The sellar protrusion contained vein-like structures and debris of red blood cells. The protrusion was located on the anterior or anterosuperior side of the notochord. No ossification center was observed around the sellar region of the embryos. Although ossification occurred in 12 of the 20 fetuses, nine of the latter showed no evidence of cleft or protrusion, indicating that the incidence of Rathke's pouch remnant was lower in the fetuses (11/20) than in the embryos (11/15). CONCLUSION: Rathke's pouch may be closed by ossification of the sphenoid, but increased cell proliferation and/or large amounts of degenerated veins may provide a structure resistant to the mechanical pressure caused by ossification.
OBJECTS: During ontogeny, part of Rathke's pouch, a physiologically superior pouching of the stomodeal ectoderm, may remain, forming the usual anomaly known as Rathke's cleft cyst. More rarely, however, the entire pouch (i.e., the craniopharyngeal canal) remains, resulting in transsphenoidal meningoencephalocele. This study is aimed to provide a better understanding of the pathogenesis. MATERIALS AND METHODS: We histologically evaluated the inferior protrusion of the putative hypophysial fossa in 35 embryonic and fetal heads, respectively (15 at 5-8 weeks and 20 at 12-16 weeks of gestation). RESULTS: In 3 of the 35 specimens, we observed a complete cleft originating from the adenohypophysis, passing through the sphenoid and connecting with the pharyngeal epithelium or pharyngobasilar fascia. In another 18 specimens, we observed a duct-like structure protruding from the fossa and ending in the sphenoid. The sellar protrusion contained vein-like structures and debris of red blood cells. The protrusion was located on the anterior or anterosuperior side of the notochord. No ossification center was observed around the sellar region of the embryos. Although ossification occurred in 12 of the 20 fetuses, nine of the latter showed no evidence of cleft or protrusion, indicating that the incidence of Rathke's pouch remnant was lower in the fetuses (11/20) than in the embryos (11/15). CONCLUSION: Rathke's pouch may be closed by ossification of the sphenoid, but increased cell proliferation and/or large amounts of degenerated veins may provide a structure resistant to the mechanical pressure caused by ossification.
Authors: Raluca Trifanescu; Olaf Ansorge; John A H Wass; Ashley B Grossman; Niki Karavitaki Journal: Clin Endocrinol (Oxf) Date: 2012-02 Impact factor: 3.478
Authors: Ji Hyun Kim; Jose Francisco Rodríguez-Vázquez; Samuel Verdugo-López; Kwang Ho Cho; Gen Murakami; Baik Hwan Cho Journal: Anat Rec (Hoboken) Date: 2011-04-28 Impact factor: 2.064
Authors: T M Mehemed; Y Fushimi; T Okada; M Kanagaki; A Yamamoto; T Okada; T Takakuwa; S Yamada; K Togashi Journal: AJNR Am J Neuroradiol Date: 2016-04-28 Impact factor: 3.825