ANATOMY AND PHYSIOLOGY
ANATOMY AND PHYSIOLOGY
The main function of eyelashes and eyelids is to protect eye from external factors, for example wind, sun, dust etc. Eyelashes are eyelid hairs that grow from of contact between the eyelid and the mucous membrane to form a protective grid around the eye.
The upper lashes are stronger and thicker. The upper lash arch has an average of 80–180 lashes and the lower lash arch has an average of 65–75 hairs. The volume of the lashes is very individual, depending on race, climate, age, diseases, etc.
Eyelashes grow in an average of 3-4 layers and on average 7-10 mm long. Lashes do not grow in sync, therefore we lose lashes every day. Eyelash cells develop in the eyelash follicles located in the dermis of the skin.
The skin consists of three layers – the stratum corneum, the epidermis and the dermis. Under the dermis is located the adipose tissue. The dermis has sebaceous and sweat glands and numerous receptors, hairs, nerves and blood vessels.
Eyelashes roots – the hair bulbs, are located in hair follicle, which are located in dermis. Close to them are located capillaries, nerves and hair arrector pili muscles.
The hair follicle is made up of fascia and epithelial tissue. At the base of the follicle is a projection. This projection is called a papilla and it contains capillaries, or tiny blood vessels, that feed the cells.
The parts of epithelial tissue are external and internal root sheath, hair bulbs and hair. At the upper part of hair follicle is formed on external root sheath, so called protuberance. Many researches have established it as a nest of stem cells, where are needful amount of renewable stem cells, which are able to keep functional all epithelial tissue parts.
If we watch eyelash cross section by microscope, then we can see, that eyelash consist of three different main layers:
The cuticle consists of several rows of smooth, transparent layers stacked on top of each other like scales. When the hair gets wet due to water or for example tears, the armor layer of hair opens (expands).
As the hair dries, this layer returns to its normal shape. Therefore do not glue an extension to wet hair (the joint will be scarce and the extension may fall off).
Cortex contains natural pigment cells that are distributed throughout the cortex giving the eyelash its characteristic color.
The medulla is the innermost part of the hair where is located so-called hair brain, which is rich of oxygen.
Each hair on our bodies has a specific length that it will grow to. After it reaches this length it goes into a resting state until it naturally falls out and is replaced by a new one. Eyelashes are no exception. There is a maximum length your eyelashes will grow to naturally, without aid, depending on genetics.
Eyelashes growth is divided into three main cycles:
Anagen phase is about 80-110 days, catagen and telogen phase are approximately 10 days, when the eyelash hair no longer grows and eventually falls out. All cycle in time (85%: 14%: 1%).