The mucosa of the cervical canal (endocervix) is composed of a single layer of mucin-secreting columnar epithelium, which lines both the surface and the underlying glandular crypts. Isolated neuroendocrine epithelial cells of argentaffin type or argyrophil type are admixed with the normal endocervical cells.
Air travel Pregnant travellers can normally travel safely by air. In the absence of medical or obstetrical complications, pregnant women can safely fly up to 36 weeks gestation. Most airlines restrict travel in late pregnancy or may require a written confirmation from a physician.
After week 28 of pregnancy, the airline may ask for a letter from your doctor or midwife confirming your due date, and that you aren't at risk of complications. Long-distance travel (longer than five hours) carries a small risk of blood clots (deep vein thrombosis, or DVT).