Probe:	Fgf-4 cDNA1
Probe preparation:	labelled with S35 RNA
Visualized with:	Autoradiography
Assay notes:	Alternating slides were hybridized with a 3' UTR probe. Identical results were obtained.

Structure	Level	Pattern	Image	Note
TS3: 8-cell stage embryo	Absent		1A

Structure	Level	Pattern	Image	Note
TS3: compacted morula	Absent		1B

Structure	Level	Pattern	Image	Note
TS6: epiblast	Strong		1C
TS6: extraembryonic component	Absent		1C
TS6: primitive endoderm	Absent		1C
TS6: trophectoderm	Absent		1C

Structure	Level	Pattern	Image	Note
TS6: epiblast	Strong		1D
TS6: extraembryonic component	Absent		1D
TS6: primitive endoderm	Absent		1D
TS6: trophectoderm	Absent		1D

Structure	Level	Pattern	Image	Note
TS28: ovary	Absent

Structure	Level	Pattern	Image	Note
TS28: testis	Absent			Fgf-4 RNA was also not detected in male germ cells.

Structure	Level	Pattern	Image	Note
TS7: epiblast	Present	Uniform	2A/B
TS7: trophectoderm	Absent		2A/B	Fgf-4 expression is not detected in the trophectoderm-derived extraembryonic ectoderm.
TS7: extraembryonic visceral endoderm	Absent		2A/B
TS7: parietal endoderm	Absent		2A/B

Structure	Level	Pattern	Image	Note
TS8: epiblast	Present	Regionally restricted	2D/E	Fgf-4 RNA is no longer detected above background levels in cells on one side of the epiblast at the embryonic/extraembryonic border.
TS8: extraembryonic ectoderm	Absent		2D/E	Fgf-4 expression is not detected in the trophectoderm-derived extraembryonic ectoderm.
TS8: extraembryonic visceral endoderm	Absent		2D/E
TS8: parietal endoderm	Absent		2D/E

Structure	Level	Pattern	Image	Note
TS9: embryo ectoderm	Present	Regionally restricted		Fgf-4 RNA could only be detected in the distal (rostral) two-thirds of the primitive streak and in ectodermal cells immediately adjacent to it.
TS9: primitive streak	Present	Regionally restricted		Fgf-4 RNA could only be detected in the distal (rostral) two-thirds of the primitive streak and in ectodermal cells immediately adjacent to it.

Structure	Level	Pattern	Image	Note
TS10: primitive streak	Present	Regionally restricted	3B/C	Fgf-4 expression is detected throughout most of the primitive streak, except near the embryonic/extrembryonic border.

Structure	Level	Pattern	Image	Note
TS10: embryo ectoderm	Present	Regionally restricted	3D/E	Fgf-4 RNA is limited to cells adjacent to positive regions of the primitive streak.
TS10: embryo mesoderm	Present	Regionally restricted	3D/E	Fgf-4 RNA is not observed as cells move laterally around the embryo, except in those mesodermal cells emerging from the distal (rostral) regions of the primitive streak where expression continues within 4-6 cell diameters of the streak.
TS10: definitive endoderm	Absent		3D/E
TS10: extraembryonic component	Absent		3D/E
TS10: embryo	Present	Regionally restricted	3D/E	Fgf-4 expression was never observed in the head process.

Structure	Level	Pattern	Image	Note
TS12: gut endoderm	Strong		4B/C
TS12: surface ectoderm	Strong		4B/C
TS12: future brain	Absent		4B/C

Structure	Level	Pattern	Image	Note
TS14: 1st branchial arch mandibular component ectoderm	Present	Regionally restricted	4D/E	Fgf-4 RNA is found in surface ectoderm covering the anterior half of the 1st (mandibular) and 2nd (hyoid) branchial arches.
TS14: 2nd branchial arch ectoderm	Present	Regionally restricted	4D/E	Fgf-4 RNA is found in surface ectoderm covering the anterior half of the 1st (mandibular) and 2nd (hyoid) branchial arches.
TS14: 1st branchial pouch endoderm	Present	Regionally restricted	4D/E	In the pharyngeal pouch endoderm, expression is limited to the lower surface of the 1st and 2nd pouch.
TS14: 2nd branchial pouch endoderm	Present	Regionally restricted	4D/E	In the pharyngeal pouch endoderm, expression is limited to the lower surface of the 1st and 2nd pouch.
TS14: 1st branchial pouch	Present	Regionally restricted	4D/E	Fgf-4 is not expressed in the medial aspects of the pouch.
TS14: 2nd branchial pouch	Present	Regionally restricted	4D/E	Fgf-4 is not expressed in the medial aspects of the pouch.
TS14: pharyngeal region	Absent		4D/E
TS14: future brain	Absent		4D/E

Structure	Level	Pattern	Image	Note
TS15: pharynx	Absent		4F/G
TS15: 1st branchial pouch	Absent		4F/G	Fgf-4 is not expressed in the medial aspects of the pouch.
TS15: 2nd branchial pouch	Absent		4F/G	Fgf-4 is not expressed in the medial aspects of the pouch.

Structure	Level	Pattern	Image	Note
TS16: 1st branchial pouch endoderm	Present
TS16: 2nd branchial pouch endoderm	Present
TS16: 3rd branchial pouch endoderm	Present
TS16: 1st branchial arch mandibular component ectoderm	Absent			Expression is not detected in surface ectoderm covering any of the branchial arches.
TS16: 2nd branchial arch ectoderm	Absent			Expression is not detected in surface ectoderm covering any of the branchial arches.
TS16: 3rd branchial arch ectoderm	Absent			Expression is not detected in surface ectoderm covering any of the branchial arches.
TS16: future brain	Absent

Structure	Level	Pattern	Image	Note
TS17: 1st branchial pouch endoderm	Trace
TS17: 2nd branchial pouch endoderm	Trace
TS17: 3rd branchial pouch endoderm	Trace
TS17: 4th branchial pouch endoderm	Trace
TS17: brain	Absent

Structure	Level	Pattern	Image	Note
TS13: head somite	Absent
TS13: trunk somite	Absent

Structure	Level	Pattern	Image	Note
TS15: trunk somite	Present	Regionally restricted	5C/D	Fgf-4 transcripts can be detected in myotome cells in mature somites that have undergone differentiation to form all three cell types.

Structure	Level	Pattern	Image	Note
TS16: tail somite	Present	Regionally restricted		Expression continues in myotomal cells, but Fgf-4 RNA becomes limited to a sub-population of the myotome.
TS16: trunk somite	Present	Regionally restricted		Expression continues in myotomal cells, but Fgf-4 RNA becomes limited to a sub-population of the myotome.

Structure	Level	Pattern	Image	Note
TS17: tail somite	Present	Regionally restricted	5E/F	Expression continues in myotomal cells, but Fgf-4 RNA becomes limited to a sub-population of the myotome, as illustrated by the observation that only a fraction of the cells that are positive for Actc-1 RNA are also Fgf-4 positive.
TS17: trunk somite	Present	Regionally restricted	5E/F	Expression continues in myotomal cells, but Fgf-4 RNA becomes limited to a sub-population of the myotome, as illustrated by the observation that only a fraction of the cells that are positive for Actc-1 RNA are also Fgf-4 positive.

Structure	Level	Pattern	Image	Note
TS19: tail somite	Present	Regionally restricted		Expression continues in myotomal cells, but Fgf-4 RNA is limited to a sub-population of the myotome.
TS19: trunk somite	Present	Regionally restricted		Expression continues in myotomal cells, but Fgf-4 RNA is limited to a sub-population of the myotome.

Structure	Level	Pattern	Image	Note
TS22: brain	Absent
TS22: tail somite	Absent			Fgf-4 is not detected in the somitic myotome or its derivatives, the skeletal muscle.
TS22: vertebral axis musculature	Absent			Fgf-4 is not detected in the somitic myotome or its derivatives, the skeletal muscle.
TS22: limb	Trace	Regionally restricted		Fgf-4 RNA was detected at very low levels within a few muscle fibers in the limb near chondrogenic sites.

Structure	Level	Pattern	Image	Note
TS16: forelimb bud mesenchyme	Absent

Structure	Level	Pattern	Image	Note
TS17: forelimb bud apical ectodermal ridge	Very strong	Regionally restricted	6A/B	Expression is spatially restricted, and is localized to the posterior half of the AER.

Structure	Level	Pattern	Image	Note
TS19: handplate apical ectodermal ridge	Absent

Structure	Level	Pattern	Image	Note
TS18: hindlimb bud apical ectodermal ridge	Present	Regionally restricted		Expression is spatially restricted, and is localized to the posterior half of the AER.

Structure	Level	Pattern	Image	Note
TS22: lower jaw tooth	Very strong	Regionally restricted	6C/D	Fgf-4 transcripts are found a very high levels within a small portion of the developing tooth bud ectoderm during the cap stage. This expression appears to be stage-specific.