Fimbria is a Latin word meaning “fringe” that is used to describe several different anatomical structures that are characterized by a fringe-like appearance. These include structures in the human brain and female reproductive system, as well as fimbriae found on some bacteria. The function of the structure depends on the organism. The practice of using the same Latin word to refer to different structures that have similar appearances or functions is very common in anatomical terminology.
In human beings, fimbriae are seen in the brain and in the fallopian tubes. The fimbria in the brain is located along the edge of the hippocampus, a structure that contributes to memory formation. This anatomical feature is made up of white matter and acts as a pathway for transmitting information. In people with brain damage, this area of the anatomy can be damaged, leading to problems with memory formation and recall. Certain neurodegenerative diseases can also damage the white matter in the fimbria.
In the female reproductive tract, the fimbria is located at the end of the fallopian tube. It responds to changing levels of sex hormones to swell at the time of ovulation in order to stimulate the ovary so that it will release an egg. Tiny hair-like structures called cilia are used to push the egg along the fallopian tube so it will reach the uterus, positioning it for fertilization. Errors in this process can lead to an egg settling in the fallopian tube, or to infertility.
Some gram negative bacteria also have fimbriae. In their case, the fringe is made from proteins and is used to help the bacteria adhere to each other to form bacterial mats, or to adhere to cells in a host. It may be located at either end of the organism or surround the entire bacterium, depending on the species. Bacteria with fimbriae are more virulent because they can attach themselves to cells in the body and stay there. Escherichia coli is an example of a bacterium that has a fimbria. Treatment for people and animals infected with such bacteria must be aggressive to dislodge or kill the bacteria.
Other animals and plants have fimbriae of their own. A genus of clams is named “Fimbria” after some distinctive anatomical features and some mosses have fringe-like structures as well. Usually, the area of the anatomy and the species involved are clear from the context of the discussion.
