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Highlights

Deirdre L. Zander, Jeremy G. Thompson, and Michelle Lane. Biol Reprod 2006; 74:288–294. Published online ahead of print 12 October 2005; 10.1095/biolreprod.105.046235

Early determinants of developmental success. One of the most exciting and important concepts emerging from reproductive and developmental biology is the long-term consequence of insults to oocytes, eggs, and early embryos to the success of fetal development and the onset of disease syndromes later in the life. The paper presented on p. 288 by Zander et al. is another important contribution to this field. This study demonstrates that exposing preimplantation embryos to ammonium during pre-compaction stages does not affect the percentage of embryos that develop to the blastocyst stage. However, embryos exposed at an early stage, compared to embryos exposed at post-compaction stages, had decreased cell numbers and inner cell mass cells. Although there was no difference in the implantation rate after transfer of blastocysts, fetal development was impaired by exposure to ammonium only at the pre-compaction stages. Therefore, the embryos at later stages of preimplantation development appear more able to cope with the ammonium stress than at the early stages. Moreover, stress at the early stage deleteriously affects subsequent fetal development.

Glial Cell-Line-Derived Neurotrophic Factor (GDNF)-Mediated RET Signaling Regulates Spermatogonial Stem Cell Fate

Cathy K. Naughton, Sanjay Jain, Amy M. Strickland, Akshay Gupta, and Jeffrey Milbrandt. Biol Reprod 2006; 74:314–321. Published online ahead of print 19 October 2005; 10.1095/biolreprod.105.047365

Signaling germline stem cell fate. A key to success of spermatogenesis during adult life is maintenance of the spermatogonial stem cells that give rise to differentiated spermatogonia. Sertoli cells secrete GDNF (glial cell-line-derived neurotrophic factor) and overexpression of this protein results in excessive germ cell proliferation and development of tumors, suggesting a role for GDNF in stem cell fate. This could be tested by examining downstream receptor and signaling elements, GFRA1 and RET, which are expressed in germ cells. However, their role has been difficult to test because neonatal lethality of mice lacking these proteins precluded determination of testicular effects. In a paper on p. 314, Naughton and co-workers make advantageous use of testis transplant strategies to tackle the role of GFRA1 and RET in spermatogonial stem cells. Transplants revealed that genetic impairment of GDNF-mediated RET signaling results in spermatogenic failure, providing more evidence for a GDNF signaling pathway in maintenance of stem cells. GFRA1 and RET are co-expressed in a subset of gonocytes at birth and RET expression coincides with that of PLZF, a protein important for stem cell function, further evidence for a critical role of RET in maintenance of the spermatogonial stem cells that ensure robust adult spermatogenesis.

John Eppig, and Mary Ann Handel

Related articles in Biol Reprod:

Perturbations in Mouse Embryo Development and Viability Caused by Ammonium Are More Severe after Exposure at the Cleavage Stages

Deirdre L. Zander, Jeremy G. Thompson, and Michelle Lane
Biol Reprod 2006 74: 288-294. [Abstract] [Full Text]  

Glial Cell-Line Derived Neurotrophic Factor-Mediated RET Signaling Regulates Spermatogonial Stem Cell Fate

Cathy K. Naughton, Sanjay Jain, Amy M. Strickland, Akshay Gupta, and Jeffrey Milbrandt
Biol Reprod 2006 74: 314-321. [Abstract] [Full Text]  

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in Biol Reprod Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Eppig, J. Articles by Handel, M. A. Search for Related Content PubMed Articles by Eppig, J. Articles by Handel, M. A. Agricola Articles by Eppig, J. Articles by Handel, M. A.