To assess the viability, sub-viability, and lethality of homozygous embryos at E18.5
- Set up timed matings with heterozygous mice
- Day 0 is defined as the midpoint of the prior dark cycle following the identification of a copulation plug.
- Collect embryos at E18.5
- Collect tissue and genotype embryos.
- Set up timed mating with heterozygous animals. Aim to dissect and collect >=28 alive embryos, otherwise lethal and subviable calls cannot be made. If more than three homozygous pups are produced before 28 pups are genotyped, a viable call can be made.
- Collect tissue for genotyping and (OPTIONAL) score Gross Morphology and/or process for Histopathology and or Imaging.
- Genotype all embryos and
- Strains that produce NO existing homozygous embryos will be considered LETHAL (complete embryonic lethality [MP:TBC]).
- Strains that produce NO live (absence of heartbeat) homozygous embryos will be considered LETHAL (complete embryonic lethality [MP:TBC]).
- Strains that produce live homozygous embryos but with an obvious defect will be left to the discretion of the center with the decision and reason recorded in the parameters.
- X-linked strains that produce NO live hemizygous male embryos from female carriers will be considered LETHAL (complete embryonic lethality [MP:TBC]).
- Flag strains that produce less than normal numbers of homozygous/hemizygous male progeny
- Strains that produce <50% expected homozygous progeny will be annotated as partial embryonic lethality [MP:TBC].
- X-linked strains that produce <50% expected male hemizygous progeny from female carriers will be considered partial embryonic lethality [MP:TBC].
All genotypes should be collected using validated assays.
Y chromosome assay required for X-linked lethal strains.
Data Analysis, annotation and display (+statistics)
Preliminary: No analysis required as it is a line level procedure. This could change with additional data about the procedure.
See E18.5 Gross Morphology protocol for MP calls of specific phenotypes at this time point.
Total Embryos: All, WT, Het, Hom
•Alive, dead, and defect (all genotyped)
Total Dead: All, WT, Het, Hom
•Dead call difficult can’t always see heart beating (E18.5)
Total Defect (Alive or Dead): All, WT, Het, Hom
•Abnormal and dead embryos
Litter size: all genotyped embryos
•ignore partials and reabsorptions.