Vaginal mucus

The vaginal epithelium is the aglandular inner lining of the vagina consisting of multiple layers of (squamous) cells. The basal membrane provides the support for the first layer of the epithelium-the basal layer. The intermediate layers lie upon the basal layer and the superficial layer is the outermost layer of the epithelium. Anatomists have described the epithelium as consisting of as many as 40 distinct layers. The mucous found on the epithelium is secreted by the cervix and uterus. The rugae of the epithelium create a involuted surface and result in a large surface area that covers 360 cm3. This large surface area allows the trans-epithelial absorption of some medications via the vaginal route. The vaginal epithelium is the aglandular inner lining of the vagina consisting of multiple layers of (squamous) cells. The basal membrane provides the support for the first layer of the epithelium-the basal layer. The intermediate layers lie upon the basal layer and the superficial layer is the outermost layer of the epithelium. Anatomists have described the epithelium as consisting of as many as 40 distinct layers. The mucous found on the epithelium is secreted by the cervix and uterus. The rugae of the epithelium create a involuted surface and result in a large surface area that covers 360 cm3. This large surface area allows the trans-epithelial absorption of some medications via the vaginal route. In the course of the reproductive cycle, the vaginal epithelium is subject to normal, cyclic changes, that are influenced by estrogen: with increasing circulating levels of the hormone, there is proliferation of epithelial cells along with an increase in the number of cell layers. As cells proliferate and mature, they undergo partial cornification. Although hormone induced changes occur in the other tissues and organs of the female reproductive system, the vaginal epithelium is more sensitive and its structure is an indicator of estrogen levels. Some Langerhans cells and melanocytes are also present in the epithelium. The epithelium of the ectocervix is contiguous with that of the vagina, possessing the same properties and function. The vaginal epithelium is divided into layers of cells, including the basal cells, the parabasal cells, the superficial squamous flat cells, and the intermediate cells. The superficial cells exfoliate continuously and basal cells replace the superficial cells that die and slough off from the stratum corneum. Under the stratus corneum is the stratum granulosum and stratum spinosum. The cells of the vaginal epithelium retain an usually high level of glycogen compared to other epithelial tissue in the body. The surface patterns on the cells themselves are circular and arranged in longitudinal rows. The epithelial cells of the uterus possess some of the same characteristics of the vaginal epithelium. Vaginal epithelium forms transverse ridges or rugae that are most prominent in the lower third of the vagina. This structure of the epithelium results in an increased surface area that allows for stretching. This layer of epithelium is protective and its uppermost surface of cornified (dead) cells that are unique in that they are permeable to microorganisms that are part of the vaginal flora. The lamina propria of connective tissue is under the epithelium. The basal layer of the epithelium is the most mitotically active and reproduces new cells. This layer is composed of one layer of cuboidal cells laying on top of the basal membrane. The parabasal cells include the stratum granulousum and the stratum spinosum. In these two layers, cells from the lower basal layer transition from active metabolic activity to death (apoptosis). In these mid-layers of the epithelia, the cells begin to lose their mitochondria and other cell organelles. The multiple layers of parabasal cells are polyhedral in shape with prominent nuclei. Intermediate cells make abundant glycogen and store it. Estrogen induces the intermediate and superficial cells to fill with glycogen. The intermediate cells contain nuclei and are larger than the parabasal cells and more flattened. Some have identified a transitional layer of cells above intermediate layer Estrogen induces the intermediate and superficial cells to fill with glycogen. Several layers of superficial cells exist that consist large, flattened cells with indistinct nuclei. The superficial cells are exfoliated continuously. The junctions between epithelial cells regulate the passage of molecules, bacteria and viruses by functioning as a physical barrier. The three types of structural adhesions between epithelial cells are: tight junctions, adherens junctions, and desmosomes. 'Tight junctions (zonula occludens) are composed of transmembrane proteins that make contact across the intercellular space and create a seal to restrict transmembrane proteins difusion. of molecules across the epithelial sheet. Tight junctions also have an organizing role in epithelial polarization by limiting the mobility of membrane-bound molecules between the apical and basolateral domains of the plasma membrane of each epithelial cell. Adherens junctions (zonula adherens) connect bundles of actin filaments from cell to cell to form a continuous adhesion belt, usually just below the microfilaments.' Junction integrity changes as the cells move to the upper layers of the epidermis. The vagina itself does not contain mucous glands. Though mucous is not produced by the vaginal epithelium, mucous originates from the cervix. The cervical mucous that is located inside the vagina can be used to assess fertility in ovulating women. The Bartholin's glands and Skene's glands located at the entrance of the vagina do produce mucous.