4.1 What is the difference between the female genital system and the female genital tract?
The female genital system refers to the external and internal genitalia. The female genital tract refers only to the tract system and therefore does not include the ovaries.
4.2 Can you think of any other examples of homeostatic control mechanisms in the body?
Control of body temperature (shivering warms us up and sweating cools us down); control of pupil diameter (bright light causes the iris to contract, whereas in dark conditions the iris widens); appetite control (hunger encourages us to eat, but a full stomach makes us stop eating); control of heart rate; control of blood glucose levels. There are many other examples.
4.3 You may need to re-read this section several times before you fully understand this complex but exquisite regulatory system. Now try to explain how oestrogen exerts its effect on the circulating levels of FSH and LH and why such apparent complexity is needed.
During the first half of each menstrual cycle oestrogen is secreted by a developing ovarian follicle and circulates freely in the bloodstream. The hypothalamus senses the increase in plasma levels of oestrogen and consequently reduces its secretion of gonadotropin-releasing hormone. This in turn reduces the secretion of gonadotropins from the pituitary. The ovaries therefore lack the required stimulus for the development of more than one or two follicles during each menstrual cycle. Although complex, this is clearly an important mechanism for limiting the number of eggs available for fertilization during any one cycle. At the end of each cycle, when the
corpus luteum degenerates and oestrogen levels decline rapidly, the negative feedback inhibition on the hypothalamus is removed. The resulting increase in gonadotropin secretion from the pituitary stimulates another cycle of ovarian follicle development.
4.4 Why doesn’t menstruation occur during pregnancy?
The survival of our species depends on the cessation of menstrual cycles during pregnancy. The physiological explanation is that the placenta provides a continuous supply of oestrogen and progesterone which inhibit gonadotropin secretion from the pituitary. This mechanism not only prevents ovarian follicle development during pregnancy but also inhibits cyclical activity in the endometrium.
4.5 How does metaplasia differ from hyperplasia?
Metaplasia is a change from one cell type to another; hyperplasia is a controlled increase in the rate of cell division.
4.6 Using the format shown in Figure 4.8, draw simple diagrams to illustrate the usual chromatin pattern and distribution seen in superficial cells and endocervical cells.
Superficial cell nucleus: uniformly distributed dense chromatin.
Endocervical cell nucleus: uniformly distributed vesicular chromatin.
4.7 Explain why post-partum cervical samples from some women show an atrophic pattern whilst others do not.
The most significant factor in determining the hormonal pattern of post-partum cervical samples is whether or not the mother breast-feeds. The act of suckling inhibits the secretion of gonadotropins from the pituitary. Under these conditions the ovaries are relatively inactive and oestrogen levels in the maternal bloodstream remain quite low. A cervical sample taken from a breast-feeding woman is therefore quite likely to contain a high proportion of parabasal cells. On the other hand, if the mother does not breast-feed, hormone levels return to normal fairly quickly and the cellular pattern resembles that of any other woman of reproductive age.
4.8 Explain why ovarian function declines and oestrogen levels drop at the time of menopause.
The ovaries contain only a limited number of viable oocytes at birth. At the time of the menopause the supply of oocytes is essentially exhausted and follicle development becomes intermittent and eventually ceases altogether. This results in a gradual decline in oestrogen secretion and menstrual cycles eventually cease.
4.9 Describe the terms orangeophilia, eosinophilia, cyanophilia, and haematoxyphilia.
4.10 In most instances the presence of non-epithelial cells in cervical samples is irrelevant, so why have we taken the time to study these?
Cells are only irrelevant when they can be identified as irrelevant cells. A few types of non-epithelial cells (such as macrophages and lymphocytes) can closely resemble neoplastic cells and must be examined closely before they can be confidently disregarded. Others, such as polymorphs, can obscure samples if they are present as an inflammatory exudate. Cytologists must be able to reliably judge when an inflammatory exudate is so excessive that it renders the sample inadequate for reporting, thus necessitating an early repeat sample.
4.11 List the main cytological features of HPV and herpes virus infections.
HPV: koilocytosis, bi- or multinucleation, nuclear enlargement, and/or hyperchromasia, dyskeratosis.
Herpesvirus: multinucleated cells, ground glass chromatin, chromatin margination, nuclear moulding, intranuclear inclusion bodies.
4.12 Why is it important for cytologists to be aware of iatrogenesis?
The damage caused to cells and tissues following medical intervention can cause changes in cell morphology that resemble neoplasia.
4.13 Why is it so important that the transformation zone is sampled for cervical screening?
The transformation zone is the area of the cervix most susceptible to neoplastic change.
4.14 How could a cytologist quickly determine the approximate number of cells in a glass slide preparation?
Multiply the number of cells per microscope field of view by the number of fields of view in the complete slide preparation. The latter is determined by dividing the area of the preparation (πR2, where R is the radius of the circular preparation) by the area of a field of view (πr2, where r is the radius of the field of view).
4.15 What are the implications of incorrectly reporting an inadequate cervical sample as adequate?
Inadequate samples should be repeated fairly quickly, usually within three months, to provide the woman and the screening service with the reassurance that an adequate screen has taken place. If such a sample is wrongly interpreted as adequate then a woman with underlying cervical abnormality would be falsely reassured and may be returned to normal recall.