Identification and characterization of stem cells in prepubertal spermatogenesis in mice.
The stem cell properties of gonocytes and prospermatogonia at prepubertal stages are still largely unknown: it is not clear whether gonocytes and prospermatogonia are a special cell type or similar to adult undifferentiated spermatogonia. To characterize these cells, we have established transgenic mice carrying EGFP (enhanced green fluorescence protein) cDNA under control of an Oct4 18-kb genomic fragment containing the minimal promoter and proximal and distal enhancers; Oct4 is reported to be expressed in undifferentiated spermatogonia at prepubertal stages. Generation of transgenic mice enabled us to purify gonocytes and prospermatogonia from the somatic cells of the testis. Transplantation studies of testicular cells so far have been done with a mixture of germ cells and somatic cells. This is the first report that establishes how to purify germ cells from total testicular cells, enabling evaluation of cell-autonomous repopulating activity of a subpopulation of prospermatogonia. We show that prospermatogonia differ markedly from adult spermatogonia in both the size of the KIT-negative population and cell cycle characteristics. The GFP(+) KIT(-) fraction of prospermatogonia has much higher repopulating activity than does the GFP(+)KIT(+) population in the adult environment. Interestingly, the GFP(+)KIT(+) population still exhibits repopulating activity, unlike adult KIT-positive spermatogonia. We also show that ALCAM, activated leukocyte cell adhesion molecule, is expressed transiently in gonocytes. Sertoli cells and myoid cells also express ALCAM at the same stage, suggesting that ALCAM may contribute to gonocyte-Sertoli cell adhesion and migration of gonoyctes toward the basement membrane.
Ohbo
Kazuyuki
K
The Sakaguchi Laboratory of Developmental Biology, School of Medicine, Keio University, Tokyo 160-8582, Japan. kohbo@sc.itc.keio.jp
Yoshida
Shosei
S
Ohmura
Masako
M
Ohneda
Osamu
O
Ogawa
Takehiko
T
Tsuchiya
Hideaki
H
Kuwana
Takashi
T
Kehler
James
J
Abe
Kuniya
K
Schöler
Hans R
HR
Suda
Toshio
T
D020410:Activated-Leukocyte Cell Adhesion Molecule / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000502:physiology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins; D006579:Heterozygote; D008164:Luminescent Proteins / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis / Q000502:physiology; D012671:Seminiferous Tubules / Q000166:cytology; D012708:Sertoli Cells / Q000166:cytology; D013093:Spermatogonia / Q000166:cytology*; D013234:Stem Cells / Q000166:cytology*; D013737:Testis / Q000166:cytology
D020410:Activated-Leukocyte Cell Adhesion Molecule; D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D019009:Proto-Oncogene Proteins c-kit