Coelomic epithelium refers to the
epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...
that lines the surface of the body wall and
abdominal
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
organs. It constitutes the outermost layer of the male and female
gonad
A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sper ...
s, thus forming the
germinal epithelium of the female or
of the male. It is also called the germinal epithelium of Waldeyer or sometimes the superficial epithelial cells in
embryology
Embryology (from Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, '' -logia'') is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and ...
. It is often encountered in the medical setting as an important source of various types of
ovarian cancer
Ovarian cancer is a cancerous tumor of an ovary. It may originate from the ovary itself or more commonly from communicating nearby structures such as fallopian tubes or the inner lining of the abdomen. The ovary is made up of three different c ...
, primary peritoneal serous cancer and
endometriosis
Endometriosis is a disease of the female reproductive system in which cells similar to those in the endometrium, the layer of tissue that normally covers the inside of the uterus, grow outside the uterus. Most often this is on the ovaries, f ...
(coelomic metaplasia). ,
During gonadal
sex
Sex is the trait that determines whether a sexually reproducing animal or plant produces male or female gametes. Male plants and animals produce smaller mobile gametes (spermatozoa, sperm, pollen), while females produce larger ones (ova, oft ...
development, the coelomic epithelium, additionally with germ cells and mesenchymal cells make the indifferent gonad. As the coelomic epithelium is confronted with XY chromosomes, they will differentiate into sertoli cells, which subsequently produce antimüllerian hormone, leading to the regression of the Müllerian duct. As the coelomic epithelium is confronted with XX chromosomes, the cells will differentiate into granulosa cells, which will not produce antimüllerian hormone and thus allow the development of the Müllerian duct.
The coelomic metaplasia theory provides a theory for the pathology of endometriosis (a condition where endometrial tissue grows outside the uterus). The coelomic epithelium develops into: peritoneum, pleura and the surface of the ovary. This combines retrograde and metaplasia and can explain the distant sites of endometriosis.
Abdomen
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