Egg cell in a fallopian tube. Animation of a human egg cell (oocyte) moving along a fallopian tube. The oocyte is released from one of a woman's two ovaries during ovulation. It then travels down the adjacent fallopian tube to the uterus. The fallopian tubes are lined with a moist mucous membrane that contains two types of cells, secretory cells and ciliated cells. The secretory cells secrete mucus, which protects the lining of the fallopian tubes. The ciliated cells are covered in microscopic hair-like structures known as cilia. These beat in wave-like motions that move the egg along the fallopian tube. If the egg is fertilised, it may embed in the lining of the uterus and develop into a baby. A mature egg cell, one of the largest cells in the human body, is around 120 micrometres in diameter.