The Cervix

Erik Odeblad
Odeblad E. 1997 Cervical mucus and their functions. The Irish Colleges of Physicians and Surgeons. 1997 26: 27-32.

"the cervix is a precision organ as complex as the eye"

The cervix is at the bottom of the uterus and channels sperm from the vagina through to the uterus. 

The figure shows the crypt types in the cervix wall which secrete the corresponding mucus type:

These mucus produce the symptomatic pattern of fertility and infertility which underpins the Billings Method.

Mucus Types

L Mucus

Eliminates low-quality sperm and provides a structure to support the S and P mucus. Produces a wet, sticky sensation at the vulva.

G Mucus

Impenetrable gestagenic mucus formed in the lowest cervical crypts. Prevents sperm entry to the cervix and is part of the immune system which protects the woman's reproductive system from infection.

F Mucus

Comes from the cells scattered throughout the length of the cervical canal and has no known special function.

Z Granules

The enzyme in the Z granules combines with the P mucus to create a liquifying effect.

S Mucus

Forms string-like channels and provides transport ("swimming lanes") for sperm cells. Produces a wet,lubricative sensation at the vulva.

P Mucus

There are a number of sub-types of this mucus, the most relevant for fertility are P2 and P6. P2 could be present as early as the beginning of the fertile phase possibly having a role in liquifying the G mucus. P6 is mostly confined to the upper part of the cervix, occurring close to the Peak of fertility, and having a role in conveying sperm. It creates a very wet and lubricative sensation at the vulva.

Carefully mapped lateral wall of the Cervix of a 20 year old virgin

Carefully mapped lateral wall of the Cervix of a 20 year old virgin