According to phases of gonadogenesis described by Clinton and Haines, 2001, in the present study, gonadogenesis of quail embryos was studied in three phases such as genital ridge
formation, gonadal differentiation, and gonadal function.
Kimura stated that true crossed testicular ectopia is only if there are two distinct deferent ducts, a common duct suggesting the development of the testis from one genital ridge
Several theories have been proposed, including peritoneal folding, segmentation of the primitive gonads longitudinal or transverse division of the genital ridge
Studying fish and reptiles, he traced their journey through the yolk sac, embryo, and back, where he found that the cell population grew from 100 at the beginning to about 4000 by the time they reached the genital ridge
. Not all of these cells would survive the trip, and some would become vagrant germ cells that settled in numerous places in the body cavity.
A layer of columnar-shaped cells covers the ventral surface of each genital ridge
. This tissue layer is the germinal epithelium.
The next stage in this genetic potential is realized when the genital ridge
in the developing fetus becomes a bi-potential gonad.
"In the mouse, SDF-1 appears to be required for the execution of the last step when the cells colonize the genital ridge
which expresses the chemokine," says Erez Raz of the Max Planck Institute for Biophysical Chemistry in Gottingen, Germany, who led the Cell study.
Kosmahl et al (3) mentioned that the occurrence of a few PSCTs in the retroperitoneal space outside the pancreas can be related to the localization of the genital ridge
during embryogenesis (1,3,7,8) and speculated that PSCTs might originate from genital ridge-related cells that were incorporated into the pancreas during organogenesis.