Cervix or Neck of the uterus

The uterine cervix (synonyms: cervix, uterine neck) represents the lower portion of the uterus; at the bottom, the cervix borders directly with the upper part of the vagina, while above it continues with the uterine isthmus, representing the junction point between the two structures:

the vagina is a cylindrical duct that receives the penis during coitus and allows the passage of the menstrual flow and the fetus during birth
the uterus receives the embryo in its own mucosa (implant) and supports its development in the fetus and the growth of the latter until the moment of birth

Through the uterine cervix, capable of undergoing important morpho-functional modifications, the spermatozoa for fertilization, the menstrual flow and the fetus at the moment of delivery pass (and become active). With the evolution of pregnancy, the uterine cervix represents a precious mechanical support that prevents the premature exit of the fetus.

The cervix is also known for the oncogenic risk, being the site of development of one of the most frequent and feared female tumors: cervical cancer.

	1) VAGINA
	2) ESOCERVICE
	3) UTERO
	4) FALLOPPIO TUBE
	5) OVAIO
	6) FIMBRIE

The uterine cervix appears as a cylinder-conical formation 2.5-4 centimeters long and 2 and a half centimeters in diameter. Its morphological characteristics, on the other hand, are variable in relation to age and parity (number of children).

Above, through the internal orifice, it communicates with the isthmus (uterine throttling, more evident in the nullipara), which in turn continues with the cavity of the uterine body, representing the junction point between the body and the cervix. Below, the cervix communicates with the vagina through the outer orifice.

In summary, the cervix is then divided into two zones:

vaginal portion (or exocervice or ectocervice or esocollo or portio vaginalis or vaginal portion) : it continues above with the endocervix and below with the vaginal mucosa through the external uterine orifice (or external ostium), protruding into the vagina like a snout of tinca (portion of the cervix that opens into the vagina)
supravaginal portion (or endocervix or endocollo or uterine portal or intrauterine portion) : it continues upward with the isthmus and the body of the uterus through the internal uterine orifice (or internal ostium), and below with the exocervix

Esocervice and uterine isthmus are joined by the endocervical canal, belonging to the endocervix : it is a channel delimited by the two uterine orifices, internal and external, characterized by some projections of the mucosa called palmate folds. As shown in the figure, this channel has the shape of a spindle: wider in the middle and narrow at the two uterine orifices, internal and external

Functions of the Cervix: Physiology

The glands of the uterine cervix secrete mucus under the influence of female sex hormones. Estrogens, whose peak occurs near ovulation, stimulate cells to secrete a viscous, transparent and acellular mucus that promotes spermatozoa survival and migration; it is precisely in the cervical canal that they acquire the fertilizing capacity (capacitation). Conversely, under the stimulus of progesterone the cervical mucous secretion becomes more dense and acidic, opposing the passage of spermatozoa in a uterine cavity not yet predisposed to implantation. On the other hand, even the external uterine orifice and the endocervical canal become wider in the pre-ovulatory phase, when the uterine neck is soft and yielding, while in subjects with hypoestrogenism or in the phases of poor estrogenic production the channel is narrower and not very yielding
The mucus secreted by the uterine cervix normally also has bacteriostatic properties to defend both the canal itself and the more internal organs of the genital sphere: uterus body and tube
During pregnancy, particularly dense mucous secretions accumulate in the cervical canal, obstructing it and creating a protective barrier for the fetus called the mucous plug. This cap is lost shortly before delivery.
During labor, the stimulation and stretching of the cervix induces a release of oxytocin, a hormone secreted by the neurohypophysis that causes the contraction of the uterus at the time of delivery

Histology: exocervice, endocervice and squamo-columnar junction

From the histological point of view:

the exocervix is internally covered by a non-keratinized paved epithelium, without glands (the same that characterizes the vagina), also called squamous epithelium
the endocervix and the endocervical canal are covered by a monostratified epithelium (synonymous: simple) columnar (synonyms: batiprismatic or cylindrical) consisting of ciliate cells and mucus-secreting cells, with the presence of endocervical glands or pseudoglytes which are more common to epithelium uterine. It is therefore also known as glandular epithelium

The two epithelia unite in the so - called squamo-columnar junction . In most adult women this passage is not abrupt: the squamocolumnar junction is an area containing irregular areas of columnar epithelium and metaplastic squamous.

The size of this area, which can be seen after applying acetic acid, varies from 2 to 15 millimeters.

The precancerous lesions of the cervix, the so-called CIN (cervical intraepithelial neopiasia), generally originate in the area of transformation extending in depth for less than 7 mm. The deeper the extent of the injury, the more serious the condition.

The cervix is not mobile because it is attached to the vagina and bladder by loose connective tissue. The body of the uterus is instead mobile, even if these movements are limited by various ligaments

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The cervical cancer has a viral origin, being caused by the Papilloma Virus (HPV), in particular by the high-risk oncogenetic strains (such as HPV 16 and HPV 18). From the time of infection (by sexual means) to that in which cervical cancer occurs there is a latency period of several years, quantifiable in at least a decade. During this time window, the screening (pap test), diagnostic (colposcopy, biopsy) and therapeutic (removal of the lesion for example by conization) protocols, allow in the vast majority of cases not only to reduce female mortality, but also to preserve uterine function and allow future pregnancies. To know more: