Exoc3l4

Most E9.5 Exoc3l4^-/- embryos are indistinguishable from littermates (n=13/15). By E10.5 most Exoc3l4^-/- embryos are smaller than littermates but only a minority delayed (n= 5/12). Almost half of the E10.5 mutants have abnormal hearts (n= 6/12) and some display pericardial edema (n= 4/12) and some have abnormal tail (n= 4/12). A minority display no gross defects (n= 2/12). By E11.5 Exoc3l4^-/- embryos are dying (such as the one displayed here) or undergoing resorption.

At E9.5, all Exoc3l4^-/- placentas examined (n=3) demonstrate largely normal development. However, an abnormally large accumulation of maternal blood is observed adjacent to the labyrinth trophoblasts.

At E10.5, all Exoc3l4^-/- placentas (n=3) exhibit multiple labyrinth zone defects compared to controls. In KO placentas, the Tfeb labelled population of labyrinth trophoblasts is markedly reduced and the subset labeled by Gcm1 is reduced. An abnormally large accumulation of maternal blood is observed adjacent to the labyrinth trophoblasts.

By E11.5, Exoc3l4^-/- placentas show a more severe manifestation of the E10.5 defects.

By E10.5 all Exoc3l4 ^-/- embryos sectioned for IF (n= 3/3) display appropriate expression of the germ layer/patterning antibodies recognizing FoxA2, SMA and SOX2. Although smaller than its littermate control this mutant is relatively normal.

Whole mount in situ hybridization with a probe recognizing endogenous Exoc3l4 does not demonstrate convincing expression in WT embryos between E8.5-10.5.

In situ hybridization (blue/purple) of sectioned WT placentas that were subsequently counterstained with eosin (pink) reveals that Exoc3l4 is expressed in the junctional zone at E8.5 (but notably absent in the maternal portion of the placenta and in the attached embryo). By E9.5 Exoc3l4 expression extends to the junctional and labyrinth zone, and by E10.5 displays restricted expression subpopulation of the labyrinth zone.

Accession number: NM_028807.4