Increased oestrogen levels elicit a secretion of mucus in the L crypts. Reabsorption by the pockets of Shaw is reduced (Figure 14) and a moist, sticky sensation commences and white baby stamps are used on the chart. Often and especially with young women there is a secretion of P mucus which has a mucolytic activity (the granules) and the plug of G mucus is dislodged and expelled. After 1-3 days there is a change, the elevated oestrogen levels stimulate the S crypts and a wet and slippery sensation (Odeblad et al. 1986) is felt, depending on the presence of L and S mucus. This phase is usually longer in the young woman (Table 3) and also with a mature parous woman. The wet and slippery sensation is much shorter in women approaching the menopause and in women who have taken the Pill for several years.

Table 3. The phases of normal ovulatory cycles explained in terms of quantities of cervical mucus secretions for women aged between 13 and 22, 23 and 37, and 39 and 47 years of age
(+), 0.5 to 1.5%; 0, <1%; +, 2 to 6%; ++, 7 to 30%; +++, >30%*

Footnotes to Table 3:

* The semi-quantitative notations 0, (+), +, ++, +++ have the same meaning as in Table 1, namely 0, not present; (+), present sometimes in small amount; +, present in small amount; ++, moderate amount; +++, large amount. They are of importance for the doctor's diagnosis of, for example, the cause of infertility. For the woman, charting the qualitative sensation at the vulva forms the important observations which are notd using coloured stamps (see Figure 15) and supplementary wording.

** Sometimes a plug.

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The last day of the slippery sensation is the Peak day, which coincides with the day of ovulation in 80% of cases, and the probability of conceiving is highest on that day. It is very important to know that the quantity of mucus is usually not at its maximum on the Peak day.

The quantity and also the stretchiness are greater on the day preceding the Peak. An exception is the older woman. For her the fertile phase is very short, only one or two days, and in this case, the quantity and the stretchiness are maximal during the Peak day.

In the young woman P mucus increases afresh about the time of ovulation and the mucolytic activity is augmented. There are two effects of this phenomenon: (i) the lubricative sensation is increased; (ii) if pregnancy is desired, there is lysis of the mucus above the S crypts and sperm cells move upwards to the uterine cavity.

Sometimes this augmented lubricative sensation is present for 2 days in young women.

After the Peak day there are 3 days of possible but decreasing fertility. Green baby stamps are used on the chart unless some traces of discharge are present when yellow baby stamps are used.

The late infertile phase (Figure 15) commences on the fourth day after the Peak. G+ mucus is produced and forms an impenetrable barrier in the cervix. Usually the sensation is one of dryness and green stamps are used. Normally there is a preponderance of G+ mucus and much less F mucus in the cervix, and vaginal mucus secretion is minimal. There is active reabsorption by the pockets of Shaw and the situation is very similar to the first infertile phase. On rare occasions some sticky mucus or vaginal discharge may flow and a yellow stamp is applied to the chart. On the first day after the Peak it is usual to find on a slide mucus types G, L, S, P and F, and also secretion Z, especially in young women (Table 3).

These cycles vary enormously. Often there is a regression of a follicle for a week and cervical secretion resembles the situation on the first infertile days. On the day after the follicle has reached its maximum size all types of mucus are visible on a microscope slide (Figures 6a and 6b). Sometimes the follicle persists for 2-3 weeks before regression commences and at other times the regression is very rapid 2-3 days before menstruation.

Some months after birth a very small number of follicles begin to grow but they do not reach maturity. In these attempts, waxing and waning of oestrogen levels are evident and wet days are appreciated. Ultimately an oestrogen level is sufficient to lead to maturation and ovulation with a Peak day takes place. It is important that these events are explained by the teacher.

I have had access to only a small number of cervical samples obtained during breast-feeding. However, it seems remarkable that there is an unexpectedly large amount of P mucus during the regress of an episode of follicle growth, not leading to maturation. This question has to be further investigated in the future.

This is a very broad subject and I can only give some examples. Diseases are general or specific.

General Diseases

Anaemias. Anaemias are usually accompanied by an increased amount of L and S mucus. After treatment, these symptoms cease.

Asthma. This illness does not alter the secretions, but treatments in which adrenaline-like remedies are used elicits an increase in the lubricative sensation.

Jaundice. Jaundice is accompanied by liver malfunction, including metabolism of steroid hormones. Irregularities in menstruation and mucus secretion are common.

Specific Diseases

Inflammation of the Cervix and Vagina. These diseases are accompanied by an increased discharge and alterations in the quality of the flow. Fertile and infertile phases are sometimes indistinguishable. After treatment this imprecision is improved.

The Pill. Complications arising from the use of the Pill are very frequent. Infertility after its use for 7-15 years is a very serious problem. S crypts are very sensitive to normal and cyclical stimulation by natural oestrogens and the Pill causes atrophy of these crypts. Fertility is impaired since the movement of sperm cells up the canal is reduced. Treatment is difficult. In some cases hormonal treatment is possible. In very intractable cases I have tried to reconstruct the S crypts microsurgically with acceptable results but the treatment is difficult and time-consuming. As already mentioned, a careful study of unsuccessful micro-operations led to the discovery of the P crypts and the P mucus.

I think that the principal secretions of the cervix have now been identified and characterized. However, several discoveries are expected, especially the enzymes produced in the isthmus of the cervix. Another important field is the cellular mechanisms involved in the differentiation and proliferation of mucus cells in the fetal cervix. The processes of reabsorption of vaginal fluids will constitute a subject for further investigation at the level of molecular biology.

We know that the Billings Ovulation Method is being used by probably more than 50 million women and families around the world, but we also know that several women have had difficulty in applying it. Today, young women are under increasing pressure to take the Pill and other hormonal contraceptives (injectables, progesterone-loaded IUD's or implants). In order to respond to these pressures it is necessary to have the knowledge and an understanding of cervico-vaginal physiology of the adolescent. In this way we are able to take care of young women in a manner that they are not deceived and so avoid using the Billings Ovulation Method but will overcome the difficulties and use that method for the rest of their lives. This is also important for the propagation of the Ovulation Method to the next generation of women and families.

I wish to acknowledge particularly my collaborators Professor Axel Ingelman-Sundberg and Dr Bertil Melén of Stockholm, Astrid Höglund, Unto Leppänen, Carin Rudolfsson-Åsberg, Carola Sjögren, and Lena Bergström of Umeå and Drs John and Evelyn Billings, Professor James Brown and Mrs Kath Smyth of Melbourne, and Dr Kevin Hume of Sydney. I wish also to acknowledge the help given to me by my family and to thank Dra Mikaela Menarguez-Carreno, University of Murcia, Spain, for electron-microscopy work and Mrs Susan Fryer, Calgary, Canada, for translating the paper from French to English. I also wish to express my thanks to Professor Lars-Eric Thornell for permission to use the TV-photomicroscope at the Department of Anatomy, University of Umeå

The morphologic classification of P mucus subtypes is P6 and P2. The used notation Pa refers to the mucolytic activity usually carried by the morphologic subtype P2.

The following corrections to the originally published version of the paper have been made.

In Figure 5: The scale divisions on the abscissa 1.0, 1,5, ... 3.0 have been corrected to 1.5,2.0, ..., 3.5.

In Table 2, the last row: The Mucolysis times for mucus types P6 and Pa of 15 hours have been corrected to 1.5 hours.