Other theories
Stem cells: Endometriosis may arise from stem cells from bone marrow and potentially other sources. In particular, this theory explains endometriosis found in areas remote from the pelvis such as the brain or lungs. Stem cells may be from local cells such as the peritoneum (see coelomic metaplasia below) or cells disseminated in the blood stream (see vascular dissemination below) such as those from the bone marrow. Vascular dissemination: Vascular dissemination is a 1927 theory that has been revived with new studies of bone-marrow stem cells involved in pathogenesis. Environment: Environmental toxins (e.g., dioxin, nickel) may cause endometriosis. Toxins such as dioxins and dioxin-like compounds tend to bioaccumulate within the human body. Further research is needed but "it is plausible that inflammatory-like processes, caused by dioxin-like environmental chemicals, can alter normal endometrial and immune cell physiology allowing persistence and development of endometrial tissue within the peritoneal cavity, normally cleared by immune system cells". Müllerianosis: A theory supported by foetal autopsy is that cells with the potential to become endometrial, which are laid down in tracts during embryonic development called the female reproductive (Müllerian) tract as it migrates downward at 8–10 weeks of embryonic life, could become dislocated from the migrating uterus and act like seeds or stem cells. Coelomic metaplasia: Coelomic cells which are the common ancestor of endometrial and peritoneal cells may undergo metaplasia (transformation) from one type of cell to the other, perhaps triggered by inflammation.
Respiratory distress can be caused by an underdeveloped trachea which collapses on inhalation or by insufficient rib cage development. Genetics
CMD is commonly caused by chromosomal abnormalities in or around the gene SOX9 on the long arm of chromosome 17, specifically at position 17q24, generally spontaneously arising or de novo mutations. Also, numerous single nucleotide variants been identified involving the SOX9 gene that cause some form of CMD. The SOX9 gene codes for a protein transcription factor which, when expressed at the embryonic stage, plays an important role in determining sexual characteristics and greatly influences skeletal development. When the SRY gene of the Y chromosome is expressed in human embryos, a cascade of gene interactions controlled by SOX9 begins and ultimately leads to male gender.. Any mutation within the coding region of SOX9 can cause campomelic dysplasia and 75% of the reported mutations lead to sex reversal. Four major classes of heterozygous SOX9 mutations can cause CMD: amino acid substitutions in the HMG-box, truncations or frameshifts that alter the C-terminal end, mutations at the splice junction, and chromosomal translocations. Additionally, mutations upstream from SOX9 can also cause CMD. Several researchers have reported cis-acting control elements upstream of SOX9. Translocation breakpoints scattered over 1Mb proximal to SOX9 indicate the presence of an extended control region.The lack of correlation between specific genetic mutations and observed phenotype, particularly with regard to sex reversal, give clear evidence of the variable expressivity of the disease.