title: Defining the spermatogonial stem cell.
abstract: Through the use of donor cells from transgenic rats expressing GFP exclusively in the germline, we have defined culture conditions where male germ cells lose (on STO cells) or maintain (on MSC-1 cells) stem cell activity. A cadre of germ cell transcripts strikingly decrease in relative abundance as a function of testis age or culture time on STO cells, but only a subset of these transcripts (approximately 248) remain elevated when cultured on MSC-1 cells. If specific gene expression regulates stem cell activity, some or all of these transcripts are candidates as such regulators. We establish a spermatogonial stem cell index (SSCI) that reliably predicts relative stem cell activity in rat or mouse testis cell cultures, and through the use of an antibody to a robust signal (Egr3) within the index find intense signals in single or paired cells. As germ cells form longer interconnected chains (incomplete cytokinesis), the Egr3 signal disappears coincident with a loss of stem cell activity. Thus, molecular markers specific for spermatogonial stem cells establish a reliable and rapid means by which to define these cells in culture and alleviate the need for laborious testicular transfers in initial cell culture studies.
authors.affiliation: Cecil H and H Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: F Kent
authors.initials: FK
authors.lastname: Hamra
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Schultz
authors.forename: Karen M
authors.initials: KM
authors.lastname: Chapman
authors.forename: Dana M
authors.initials: DM
authors.lastname: Grellhesl
authors.forename: Jennifer T
authors.initials: JT
authors.lastname: Cronkhite
authors.forename: Robert E
authors.initials: RE
authors.lastname: Hammer
authors.forename: David L
authors.initials: DL
authors.lastname: Garbers
mesh_terms: D000818:Animals; D020869:Gene Expression Profiling; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000032:analysis; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D017207:Rats, Sprague-Dawley; D013093:Spermatogonia / Q000166:cytology*; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins