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Germ Cell Transplantation and Testis Tissue Xenografting in Mice
Published on: February 6, 2012
Testicular feminization: a model for testicular descent in mice and men
Abstract:
The position of the testis was determined in patients and mice with the testicular feminization (TFM) syndrome, to answer the question, do androgens cause testicular descent? In 16 children with complete or partial TFM syndrome with androgen insensitivity, plus two children with a deficiency of androgen secretion, the testes were at or beyond the internal inguinal ring in 35 out of 36 instances. In male mice with TFM, the testes had descended normally to the internal ring by the time of birth but further descent was absent. These observations suggest testicular descent is a two-stage process comprising transabdominal and transinguinal phases. The first phase is not controlled by androgen, and hence is normal in TFM; by contrast the second phase is androgen-dependent, and absent in TFM. It is speculated that the first phase may be regulated by Müllerian Inhibiting Substance, although this is unproven. Because testicular descent in TFM can be separated into two stages, the TFM mouse should prove a useful model for studying the hormonal control of descent of the testis.
Insights
Androgens do not cause testicular descent, which occurs in two stages. The first stage is androgen-independent, while the second stage requires androgens, as seen in testicular feminization (TFM) syndrome.
Area of Science:
- Endocrinology
- Developmental Biology
- Reproductive Medicine
Background:
- Testicular descent is crucial for male fertility.
- The role of androgens in testicular descent is not fully understood.
- Testicular feminization (TFM) syndrome offers a unique model to study hormonal influences.
Purpose of the Study:
- To investigate the role of androgens in the two-stage process of testicular descent.
- To determine if androgens are essential for both phases of testicular descent.
- To utilize patients and mice with TFM syndrome to elucidate hormonal control mechanisms.
Main Methods:
- Assessed testicular position in children and mice with TFM syndrome.
- Correlated testicular position with androgen insensitivity or deficiency.
- Observed testicular descent patterns in relation to developmental stages.
Main Results:
- In TFM patients, testes were at or beyond the internal inguinal ring in 35/36 cases, indicating normal early descent.
- In TFM mice, testes descended to the internal ring by birth but failed to descend further.
- These findings suggest a two-stage testicular descent process, with the second stage being androgen-dependent.
Conclusions:
- Testicular descent is a two-stage process: a non-androgen-dependent transabdominal phase and an androgen-dependent transinguinal phase.
- TFM syndrome provides a valuable model for studying the hormonal regulation of testicular descent.
- Müllerian Inhibiting Substance is a potential regulator of the first phase of testicular descent.
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