Early Regressive Development of the Subcommissural Organ of Two Human Fetuses with Non-Communicating Hydrocephalus

Abstract

Hydrocephalus is a central nervous system condition characterized by CSF buildup and ventricular hypertrophy. It is divided into two types: communicative and non-communicating hydrocephalus. Congenital hydrocephalus has been linked to several changes in the subcommissural organ (SCO). However, it is unclear whether these changes occur before or as a result of the hydrocephalic illness. This report presents three cases of human fetuses with hydrocephalus: one non-communicating case, two communicating cases, and two controls. Hematoxylin-Eosin (H&E) or cresyl violet and immunohistochemistry with anti-transthyretin were used to analyze SCO morphological and secretory changes. We conclude that in the cases presented here, there could be an early regression in the SCO of the communicating cases that is not present in the non-communicating case.

Keywords: human congenital hydrocephalus; subcommissural organ; transthyretin.

Figure 1

(A) Panoramic view of the SCO of a 21GW non-hydrocephalic control fetus (C1), stained with hematoxylin-eosin (bar = 250 μm). (A1): precommissural part of the SCO (bar = 25 μm), (A2): subcommissural part of the SCO (bar = 25 μm), (A3): retrocommissural part of the SCO (bar = 25 μm). (B) Panoramic view of the SCO of a 22GW non-hydrocephalic control fetus (C2) (bar = 250 μm), stained with cresyl violet. (B1): precommissural part of the SCO (bar = 25 μm), (B2): subcommissural part of the SCO (bar = 25 μm), (B3): retrocommissural part (bar = 25 μm). (C) Panoramic view of the SCO of a fetus with non-communicating hydrocephalus (Dandy–Walker) of 21GW (H1) (bar = 250 μm), stained with hematoxylin-eosin. (C1): precommissural part of the SCO (bar = 25 μm), (C2): subcommissural part of the SCO (bar = 25 μm), (C3): retrocommissural part (bar = 25 μm). (D) Panoramic view of the SCO of a fetus with communicating hydrocephalus of 22 GW (H2) (bar = 250 μm), stained with hematoxylin-eosin. (D1): precommissural part of the SCO (bar = 25 μm), (D2): subcommissural part of the SCO (bar = 25 μm), (D3): retrocommissural part (bar = 25 μm). (E) Panoramic view of the SCO of a fetus with communicating hydrocephalus of 22 GW (H3) (bar = 250 μm), stained with hematoxylin-eosin. (E1): precommissural part of the SCO (bar = 25 μm), (E2): subcommissural part of the SCO (bar = 25 μm), (E3): retrocommissural part (bar = 25 μm). For all pictures: GW = gestational week MR = mesocoelic recess, PC = posterior commissure, PG = pineal gland, PRC = precommissural or rostral region of the SCO, RC = retrocommissural or caudal region of the SCO, SCO = subcommissural organ, SC = subcommissural or middle region of the SCO, ependymal cells, hypendymal cells.

Figure 2

(A) Panoramic view of the SCO of a 21GW non-hydrocephalic control fetus (C1), labeled with anti-transthyretin (TTR-ir) (bar = 250 μm). (A1): precommissural part of the SCO (bar = 25 μm), (A2): subcommissural part of the SCO (bar = 25 μm), (A3): retrocommissural part of the SCO (bar = 25 μm). (B) Panoramic view of the SCO of a 22GW non-hydrocephalic control fetus (C2), labeled with anti-transthyretin (TTR-ir) (bar = 250 μm), (B1): precommissural part of the SCO (bar = 25 μm), (B2): subcommissural part of the SCO (bar = 25 μm), (B3): retrocommissural part (bar = 25 μm). In both cases controls TTR-ir is observed in group of ependymal cells and several hypendymal cells in the three parts of SCO. (C) Panoramic view of the SCO of a 21GW (H1) fetus with non-communicating hydrocephalus (Dandy–Walker), labeled with anti-transthyretin (TTR-ir) (bar = 250 μm), (C1): precommissural part of the SCO (bar = 25 μm), (C2): subcommissural part of the SCO (bar = 25 μm), (C3): retrocommissural part (bar = 25 μm). (D) Panoramic view of the SCO of a fetus with communicating hydrocephalus of 22 GW (H2), labeled with anti-transthyretin (TTR-ir) (bar = 250 μm), (D1): precommissural part of the SCO (bar = 25 μm), (D2): subcommissural part of the SCO (bar = 25 μm), (D3): retrocommissural part (bar = 25 μm). (E) Panoramic view of the SCO of a fetus with communicating hydrocephalus of 22 GW (H3), labeled with anti-transthyretin (TTR-ir) (bar = 250 μm). (E1): precommissural part of the SCO (bar = 25 μm), (E2): subcommissural part of the SCO (bar = 25 μm), (E3): retrocommissural part (bar = 25 μm). For all pictures: GW = gestational week MR = mesocoelic recess, PC = posterior commissure, PG=pineal gland, PRC = precommissural or rostral region of the SCO, RC = retrocommissural or caudal region of the SCO, SCO = subcommissural organ, SC = subcommissural or middle region of the SCO, ependymal cells, (▲) hypendymal cells. In the case of non-communicating hydrocephalus, TTR-ir can be observed in the rostral and caudal parts of the SCO. However, in the H2 case of communicating hydrocephalus, the TTR-ir can mainly be observed in the sub and retrocomisural parts of the SCO and located in the ependymal cells. In the H3 case of communicating the TTR-ir is in the ependymal cells of the retro-commissural parts, mainly in its apical pole.