The sex-determining gene on the Y chromosome, named Sry, initiates differentiation of gonadal somatic cells into testes, which in turn regulate the development of male phenotype. / The B6.YTIR sex-reversed mouse provides a good model for studying sex-determining mechanisms. We proposed a hypothesis that the testis-determining pathway is impaired downstream of Sry transcription in the B6.YTIR fetus. / The current study aimed to determine the hierarchical order of Sry, Sox9, Pn1, and Mis by examining their expression in B6.YTIR gonads as compared to normal B6.XY gonads by RT-PCR. / Results. Sry expression was comparable between B6.Y TIR and B6.XY gonads, with its onset between 10.5 and 11.5 dpc, a peak at 11.5 dpc, and downregulation thereafter. Sox9 expression was detectable in both B6.XX and B6.XY gonads at 11.5 dpc at comparable levels, but was then downregulated in B6.XX gonads at 12.5 dpc, by which stage testicular cord formation had began in B6.XY gonads. Pn1 was expressed in both B6.XX and B6.XY gonads at comparable levels at 11.5 dpc and was upregulated in B6.XY gonads at 12.5dpc. Mis expression in B6.Y TIR gonads was low at 10.5 and 11.5 dpc with a peak at 12.5dpc and higher levels only in ovotestes at 14.5dpc. / These results indicate that all Sox9, Pn1, and MIS genes follow a sexually dimorphic pattern of expression associated with development of testicular cords. Therefore, these genes are placed downstream of Sry in the fetal mouse gonad. Furthermore, we conclude that the testis-determining pathway is impaired upstream of Sox9 and Pn1 and Mis in the B6.YTIR gonad. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.79021 |
| Date | January 2002 |
| Creators | Lalous, Maria |
| Contributors | Taketo, Teruko (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001984241, proquestno: AAIMQ88236, Theses scanned by UMI/ProQuest. |
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