Antibody:	Anti-Stella/Dppa3 AF2566
Detection system:	Biotinylated secondary antibody/[Strept]avidin coupled to horseradish peroxidase

Structure	Level	Pattern	Image	Note
TS9: conceptus	Absent

Structure	Level	Pattern	Image	Note
TS12: allantois	Present	Regionally restricted	1A	Expression was detected in the base of the allantois.

Structure	Level	Pattern	Image	Note
TS20: germ cell of ovary	Present		1C

Structure	Level	Pattern	Image	Note
TS20: germ cell of testis	Present		1D

Structure	Level	Pattern	Image	Note
TS10: extraembryonic component	Present	Regionally restricted	1E	A cluster of cells was localized to the extraembryonic primitive streak.

Structure	Level	Pattern	Image	Note
TS11: primitive streak	Present		1F
TS11: extraembryonic component	Present	Regionally restricted	1F	A cluster of cells was localized to the extraembryonic primitive streak.
TS11: amnion ectoderm	Present	Single cells	1F	Immunopositive cells were occasionally observed in the amniotic ectoderm.
TS11: extraembryonic visceral endoderm	Present	Regionally restricted	1F	Occasional staining was noted in the allantois-associated extraembryonic visceral endoderm within cytoplasmic vesicles of varying sizes.
TS11: amnion mesoderm	Absent		1F

Structure	Level	Pattern	Image	Note
TS12: allantois	Present	Regionally restricted	1G	Expression was detected in the proximal region of the allantoic core domain. An occasional positive cell was noted in the distal allantoic core domain, but never in the extreme distal allantois at this stage.
TS12: primitive endoderm	Present		1G
TS12: primitive streak	Present		1G
TS12: extraembryonic visceral endoderm	Present	Regionally restricted	1G	Expression was detected in the allantois-associated extrembryonic visceral endoderm.
TS12: amnion ectoderm	Present		1G inset , 1G

Structure	Level	Pattern	Image	Note
TS12: embryo	Present	Regionally restricted	1H1	Expression was dispersed across the dorsal-ventral axis of the posterior embryo.
TS12: primitive endoderm	Present		1H1

Structure	Level	Pattern	Image	Note
TS12: allantois	Present	Regionally restricted	1H2	Expression was detected in the allantoic core domain. The cells formed a tight cluster within the midline.
TS12: extraembryonic visceral endoderm	Present	Regionally restricted	1H2	Expression was detected in the allantois-associated extraembryonic visceral endoderm.

Structure	Level	Pattern	Image	Note
TS12: allantois	Present	Regionally restricted	1H3	Expression was detected in the allantoic core domain. The cells formed a tight cluster within the midline.
TS12: extraembryonic visceral endoderm	Present	Regionally restricted	1H3	Expression was detected in the allantois-associated extraembryonic visceral endoderm.

Structure	Level	Pattern	Image	Note
TS12: allantois	Present	Regionally restricted	1I	Expression was detected in the allantoic core domain.
TS12: amnion ectoderm	Present		1I
TS12: primitive endoderm	Present		1I
TS12: primitive streak	Present		1I
TS12: extraembryonic visceral endoderm	Present	Regionally restricted	1I	Expression was detected in the allantois-associated extrembryonic visceral endoderm and the ventral cuboidal mesothelium-associated extraembryonic visceral endoderm.

Structure	Level	Pattern	Image	Note
TS12: allantois	Present	Regionally restricted	1J	Expression in the allantoic core domain was less clustered and more scattered by the 5 somite stage.
TS12: amnion ectoderm	Present		1J
TS12: primitive endoderm	Present		1J
TS12: primitive streak	Present		1J
TS12: extraembryonic visceral endoderm	Present	Regionally restricted	1J	Expression was detected in the allantois-associated extrembryonic visceral endoderm and the ventral cuboidal mesothelium-associated extraembryonic visceral endoderm.
TS12: hindgut diverticulum endoderm	Present		1J , 1J inset

Structure	Level	Pattern	Image	Note
TS12: hindgut diverticulum endoderm	Present	Regionally restricted	2A1	Expression was detected in the dorsal and ventral hindgut.
TS12: conceptus	Present	Regionally restricted	2A1	Expression was detected at the site of amniotic insertion at the embryonic-extraembryonic junction.
TS12: surface ectoderm	Present	Regionally restricted	2A1	A small population of positive cells persisted within the surface ectoderm near the allantoic-amniotic junction.

Structure	Level	Pattern	Image	Note
TS12: hindgut diverticulum endoderm	Present	Regionally restricted	2A2	Expression was detected in the ventral hindgut.
TS12: conceptus	Present	Regionally restricted	2A2	Expression was detected at the site of amniotic insertion at the embryonic-extraembryonic junction.
TS12: primitive streak	Present		2A2
TS12: trunk mesenchyme	Present	Regionally restricted	2A2	A range of cells persisted in the posterior mesoderm of the developing tailbud.
TS12: surface ectoderm	Present	Regionally restricted	2A2	A small population of positive cells persisted within the surface ectoderm near the allantoic-amniotic junction.

Structure	Level	Pattern	Image	Note
TS12: hindgut diverticulum endoderm	Present	Regionally restricted	2A3	Expression was detected in the ventral hindgut.
TS12: primitive streak	Present		2A3
TS12: allantois	Present	Regionally restricted	2A3	Expression was found within the proximal allantois. Some of these cells were in the vessel of confluence.

Structure	Level	Pattern	Image	Note
TS13: allantois	Present	Regionally restricted	2B	Expression was detected in a cluster of cells in the midregion of the allantois.
TS13: hindgut diverticulum endoderm	Present	Regionally restricted	2B	Expression was localized to the ventral endoderm, near the omphalomesenteric artery.

Structure	Level	Pattern	Image	Note
TS12: primitive endoderm	Present	Regionally restricted	2C1	Expression was localized to the endoderm at the leading edge of the open hindgut. No positive cells were detected in the presumptive dorsal hindgut endoderm.

Structure	Level	Pattern	Image	Note
TS12: hindgut diverticulum endoderm	Present	Regionally restricted	2C2	In the anterior-most segment of closed hindgut, positive cells were localized to the ventral, but not dorsal side.

Structure	Level	Pattern	Image	Note
TS12: hindgut diverticulum endoderm	Present	Regionally restricted	2C3	Moving posteriorly along the hindgut tube, staining continued in the ventral hindgut, but some staining was also localized to the dorsal hindgut.
TS12: embryo mesenchyme	Present	Regionally restricted	2C3	Expression was detected in the posterior mesenchyme.
TS12: surface ectoderm	Present	Regionally restricted	2C3	Exression was detected in the posterior dorsal surface ectoderm.

Structure	Level	Pattern	Image	Note
TS12: primitive streak	Present		2C4
TS12: trunk mesenchyme	Present	Regionally restricted	2C4	A range of cells persisted in the posterior mesoderm of the developing tailbud.
TS12: surface ectoderm	Present	Regionally restricted	2C4	A few positive cells were occasionally observed within the distal posterior surface ectoderm.

Structure	Level	Pattern	Image	Note
TS12: allantois	Present		2C5

Structure	Level	Pattern	Image	Note
TS13: hindgut diverticulum	Present	Regionally restricted	2D	Expression was detected in the ventral hindgut.
TS13: embryo mesenchyme	Present	Regionally restricted	2D	Expression was in posterior loose mesenchyme.
TS13: surface ectoderm	Present		2D

Structure	Level	Pattern	Image	Note
TS13: somatopleure	Present			Staining was occasionally seen in the mesoderm of the somatopleure.

Structure	Level	Pattern	Image	Note
TS13: hindgut diverticulum	Present	Regionally restricted	2E1	Expression was localized to the ventral hindgut.

Structure	Level	Pattern	Image	Note
TS13: surface ectoderm	Present	Regionally restricted	2E2	Expression was near the surface ectoderm of the tailbud.

Structure	Level	Pattern	Image	Note
TS13: embryo ectoderm	Present	Regionally restricted	2E3	Expression was in the ventral ectoderm ridge of the posterior embryo.
TS13: allantois	Present	Regionally restricted	2E3	Positive cells appeared sporadically either as a single cell or a small cluster of cells throughout the length of the allantois. This section shows positive cells on the mesothelial surface.

Structure	Level	Pattern	Image	Note
TS13: allantois	Present	Regionally restricted		Positive cells appeared sporadically either as a single cell or a small cluster of cells throughout the length of the allantois. Positive cells were within the core.

Structure	Level	Pattern	Image	Note
TS13: blood island	Present	Single cells	3A
TS13: yolk sac endoderm	Present	Regionally restricted	3A	Expression was localized within vesicles of the extraembryonic visceral endoderm of the visceral yolk sac.

Structure	Level	Pattern	Image	Note
TS12: chorion ectoderm	Present	Diffuse	3B

Structure	Level	Pattern	Image	Note
TS12: extraembryonic visceral endoderm	Strong	Single cells	3B upper right inset	Stained cell nucleus in the allantois-associated extraembryonic visceral endoderm.