The scanning electronmicroscopy of human cervical mucus in the non-pregnant and pregnant states.

The ultrastructure of the high viscosity phase of human cervical mucus was studied by scanning electronmicroscopy. In the normal woman, sequential mucus samples taken throughout the menstrual cycle showed a honeycomb-like structure with interconnecting channels separated by thin membraneous walls. The diameter of the channels in the mucus was 2 to 6 mum in the early follicular phase, 30 to 35 mum in the late follicular phase and 4 to 6 mum in the luteal phase. During the first trimester of pregnancy and also at the beginning and end of the menstrual cycle a compact, dense form of mucus structure was observed. In women using either copper-releasing or pharmacologically inert intrauterine contraceptive devices (IUCDs), the basic structure was similar to that seen in normal women. The channel diameters were normal in women using the inert IUCD but the mucus from women using a copper-releasing IUCD showed a slight decrease in the late follicular phase channel diameter which was dependent on the time the device had been in place. Globular appendages to the membraneous walls of the mucus were observed in the presence of a copper-releasing IUCD.