Cervix or Neck of the uterus

The uterine cervix (synonyms: cervix, cervix) represents the lower portion of the uterus; at the bottom, the cervix borders directly with the upper part of the vagina, while at the top it continues with the uterine isthmus, representing the junction 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 childbirth
the "uterus receives the embryo in its own mucosa (implant) and supports its development into the fetus and the" growth of the latter "until the moment of delivery

Through the uterine cervix, capable of undergoing important morpho-functional modifications, the spermatozoa pass (and become active) for fertilization, menstrual flow and the fetus at the moment of delivery. With the evolution of pregnancy, the uterine cervix represents a precious mechanical support that prevents the premature exit of the fetus.
The uterine cervix is also known for its oncogenic risk, being the site of the development of one of the most frequent and feared female cancers: cervical cancer.

1) VAGINA 2) EXOCERVICE 3) UTERUS 4) FALLOPIUM TUBE 5) OVE 6) FIMBRIE

The uterine cervix appears as a cylindro-conical formation with a length of 2.5-4 centimeters and a diameter of 2 and a half centimeters. 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 constriction, 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 neck of the uterus. the cervix communicates with the vagina through the external orifice.

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

vaginal portion (or exocervix or ectocervix or exocollo or portio vaginalis or vaginal portion): it continues at the top with the endocervix and at the bottom with the vaginal mucosa through the external uterine orifice (or external ostium), protruding into the vagina like a snout of tench (portion of the uterine neck that flows into the vagina)
supravaginal portion (or endocervix or endocollo or uterine portio or intrauterine portion): it continues superiorly with the isthmus and the body of the uterus through the internal uterine orifice (or internal ostium), and at the bottom with the exocervix

The exocervix and uterine isthmus are joined by the endocervical canal, belonging to the endocervix: it is a canal delimited by the two uterine orifices, internal and external, characterized by some protrusions of the mucosa called palmate folds. As shown in the figure, this canal has the shape of a spindle: wider in the middle part and narrow in correspondence of 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 the cells to secrete a viscous, transparent and acellular mucus which favors the survival and migration of spermatozoa; it is precisely in the cervical canal that they acquire the fecundating capacity (capacitation). Conversely, under the stimulus of progesterone the cervical mucous secretion becomes denser and more acidic, opposing the passage of spermatozoa into a uterine cavity not yet predisposed to implantation. in the pre-ovulatory phase, when the uterine neck is soft and yielding, while in subjects with hypoestrogenism or in the phases of low estrogen production the canal is narrower and not very yielding
The mucus secreted by the uterine cervix normally also possesses bacteriostatic properties in defense of both the canal itself and the innermost organs of the genital sphere: the body of the uterus and the fallopian tubes.
During pregnancy, particularly thick mucous secretions accumulate in the cervical canal obstructing it and creating a protective barrier for the fetus called a mucous plug. This cork is lost just before delivery.
During labor, stimulation and stretching of the cervix induce a release of oxytocin, a hormone secreted by the neurohypophysis that causes the uterus to contract at the time of delivery.

Histology: exocervix, endocervix and squamo-columnar junction

From the histological point of view:

the exocervix is internally covered by a glandless, non-keratinized, multi-layered paving epithelium (the same that characterizes the vagina), also called squamous epithelium
the endocervix and the endocervical canal are covered by a monostratified epithelium (synonyms: simple) columnar (synonyms: batiprismatic or cylindrical) made up of hair cells and mucus secreting cells, with the presence of endocervical glands or pseudoglands that most closely associate it with the epithelium uterine. It is therefore also known as the glandular epithelium

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

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

Precancerous lesions of the cervix, the so-called CIN (cervical intraepithelial neopiasias), generally originate in the transformation zone extending in depth for less than 7 mm. The deeper the extension of the lesion, the more serious the condition.

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

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