Area postrema: fetal maturation, tumours, vomiting centre, somatic growth and role in neuromyelitis optica
Bibliographic record
Abstract
The area postrema (AP) in the caudal 4th ventricular floor is unique, highly vascular without blood/brain or /CSF barrier. In addition to its function as the vomiting centre, several other important functions are: part of the circumventricular organs for vasomotor and angiotensin II regulation; a role in neuromyelitis optica related to aquaporin-4; contributor to fetal and postnatal somatic growth. Functions are immature at birth. The purpose of this study was to demonstrate AP neuronal/synaptic/glial maturation in normal fetuses and 3 AP tumours. Transverse sections of the caudal 4th ventricle of 18 normal human fetal brains at autopsy, 6 to 40 weeks were examined; also 3 infants 3-18mos; 2 children. A battery of immunocytochemical neuronal and glial markers: MAP2; calretinin; synaptophysin; vimentin; nestin; GFAP; S-100β protein; were applied to paraffin sections. Two children with AP tumours and one with neurocutaneous melanocytosis, all with pernicious vomiting, were studied. In normal fetuses, AP neurons exhibited cytological maturity and well-formed synaptic circuitry by 14wk gestation. Size/volume increase was disproportionately greater than brainstem growth in 2nd and 3rd trimesters and postnatally. Astrocytes co-expressed vimentin/GFAP but glia were best demonstrated by S-100β protein. Ependyma over the AP in fetuses is simple cuboidal, adjacent to pseudostratified columnar of the 4th ventricular floor. Melanocytes infiltrated AP in the toddler with pernicious vomiting; 2 children had primary AP pilocytic astrocytomas. Though AP is cytologically mature by 14wk, growth increases and functions mature into the postnatal months. We recommend that AP neuropathology include synaptophysin and S-100β at autopsy if AP dysfunction suspected. LEARNING OBJECTIVES This presentation will enable the learner to: 1. Explain the maturation of neurons, synaptic circuits and glial elements of the AP 2. List and recognize tumours that can affect the area postrema 3. Describe functions of the area postrema
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".