Characterization of developing bowel transplanted from transgenic erythropoietin receptor-deficient mouse embryos.
BACKGROUND
Erythropoietin (Epo) receptors (EpoR) are present in embryonic and postnatal mammalian bowel, and activation of EpoR signaling with recombinant Epo (rEpo) has trophic effects. Transgenic mice with absent Epo function are embryonic lethal, so it is not known whether Epo function is required for bowel development.


OBJECTIVE
To characterize bowel structure in the absence of EpoR signaling.


METHODS
Heterozygous EpoR knockout mice were mated. Bowel segments from their embryos were dissected and transplanted beneath the renal capsule of adult wild-type mice and residual embryo tissue was excised for genotyping. Transplants were harvested at 7, 14 or 21 days. The transplanted bowel segments were immunostained to identify proliferation (BrdU+), as well as neuronal (PGP9.5+), endothelial (vWF+), and neuroendocrine (synaptophysin+) cells. Gross and microscopic characteristics of intestinal differentiation were evaluated.


RESULTS
50 transplants were performed: bowel from 49 embryos survived to harvest and 43 showed evidence of bowel development with appropriate small or large intestinal features. No differences in morphology, immunolabeling, or BrdU incorporation were observed between homozygous-null, heterozygote or wild-type bowel. Smooth muscle and mucosal cells were present, along with neuronal, endothelial, and neuroendocrine cells in all genotypes.


CONCLUSIONS
Enteric EpoR signaling is not essential for intestinal morphogenesis.
Department of Pediatrics, University of Washington, WA 98195, USA.
Marcella
M
Mascher-Denen
Ronald J
RJ
McPherson
Raj P
RP
Kapur
Sandra E
SE
Juul
D000818:Animals; D007422:Intestines / Q000033:anatomy & histology / Q000196:embryology* / Q000637:transplantation*; D051379:Mice; D018345:Mice, Knockout; D038081:Organogenesis / Q000502:physiology; D017467:Receptors, Erythropoietin / Q000172:deficiency* / Q000235:genetics; D019737:Transplants
D017467:Receptors, Erythropoietin