Antibody:	anti-periostin
Detection system:	horseradish peroxidase
Assay notes:	Sections were counterstained with hematoxylin, unless otherwise indicated.

Structure	Level	Pattern	Image	Note
TS20: brain white matter	Present	Regionally restricted	2E	Expression in presumptive pyramidal tract.
TS20: medulla oblongata	Present	Regionally restricted	2E	Expression in medullary differentiating field.

Structure	Level	Pattern	Image	Note
TS20: vertebral cartilage condensation	Weak	Widespread	2F	Weak expression in mesenchymal cells in and around developing vertebral cartilage. Widespread expression throughout mesenchymal cells.

Structure	Level	Pattern	Image	Note
TS20: heart atrium	Present	Regionally restricted	2G	Expression in atrium of developing heart. Expression in cushion cells.

Structure	Level	Pattern	Image	Note
TS20: spinal cord	Present	Regionally restricted	3G	Expression in basal plate of spinal cord and marginal layer. No expression in alar plate.

Structure	Level	Pattern	Image	Note
TS20: medulla oblongata marginal layer	Present		3I
TS20: glossopharyngeal ganglion	Absent		3I

Structure	Level	Pattern	Image	Note
TS20: ganglionic eminence	Present	Regionally restricted		Expression in ganglionic eminence and pons differentiating fields.
TS20: pons	Present	Regionally restricted		Expression in ganglionic eminence and pons differentiating fields.
TS20: forebrain-midbrain boundary region	Weak	Regionally restricted		Weak expression in tectum differentiating field.

Structure	Level	Pattern	Image	Note
TS21: ganglionic eminence	Present	Regionally restricted	4E	Expression in ganglionic eminence differentiating field.
TS21: rib cartilage condensation	Strong		4E	Authors report higher levels of expression than seen for PLF in cells of cartilaginous vertebra and ribs.
TS21: vertebral cartilage condensation	Strong		4E	Authors report higher levels of expression than seen for PLF in cells of cartilaginous vertebra and ribs.
TS21: heart	Present		4E

Structure	Level	Pattern	Image	Note
TS21: brain white matter	Present	Regionally restricted	4F	Expression in presumptive pyramidal tract.
TS21: medulla oblongata	Strong	Regionally restricted	4F	Strong expression in presumptive medulla differentiating field.
TS21: cochlea	Absent		4F

Structure	Level	Pattern	Image	Note
TS21: vertebral cartilage condensation	Present	Regionally restricted	4G

Structure	Level	Pattern	Image	Note
TS21: peripheral nerve	Strong	Regionally restricted	4H	Expression in chondrocytes in developing vertebral body.
TS21: dorsal root ganglion	Absent		4H

Structure	Level	Pattern	Image	Note
TS21: pons	Present	Regionally restricted		Expression in pons differentiating field.
TS21: spinal cord	Present	Regionally restricted		Expression in spinal cord basal plate.
TS21: spinal nerve	Present	Regionally restricted		Expression in subset of spinal nerves.
TS21: thalamus	Weak	Regionally restricted		Weak expression in dorsal thalamus.
TS21: forebrain-midbrain boundary region	Weak	Regionally restricted		Weak expression in tectum differentiating field.

Structure	Level	Pattern	Image	Note
TS24: brain	Absent		5D
TS24: spinal cord	Absent		5D

Structure	Level	Pattern	Image	Note
TS24: rib	Present	Regionally restricted	5F	Expression in cells within developing rib and in the perichondrial area. Expression primarily in mesenchymal cells of perichondrium and to a lesser extent chondrocytes of developing bones.

Structure	Level	Pattern	Image	Note
TS24: forelimb skeleton	Present	Regionally restricted	7E	Strongest expression in hypertrophic regions. Lower expression in chondrocytes in prehypertrophic zone and proliferating regions.

Structure	Level	Pattern	Image	Note
TS24: forelimb bone	Present	Regionally restricted	7F	Strongest expression in hypertrophic regions. Lower expression in chondrocytes in prehypertrophic zone and proliferating regions.

Structure	Level	Pattern	Image	Note
TS24: forelimb mesenchyme	Weak	Regionally restricted	7F lower inset	Low levels of expression in cytoplasm; no expression in nuclei.

Structure	Level	Pattern	Image	Note
TS26: brain	Trace		9A	Authors report little or no expression in brain regions and brain white matter regions.
TS26: vagus nerve	Weak	Diffuse	9A	Diffuse low levels of expression in vagal nerve fascicles in thoracic region.

Structure	Level	Pattern	Image	Note
TS26: rib	Weak	Regionally restricted	9B	Faint expression in vagus nerve branch located in the anterior neck.

Structure	Level	Pattern	Image	Note
TS26: cerebral cortex	Weak		9C	Only very faint expression in hippocampus and surrounding cortex.
TS26: hippocampus	Weak		9C	Only very faint expression in hippocampus and surrounding cortex.

Structure	Level	Pattern	Image	Note
TS26: brain white matter	Trace	Regionally restricted	9D	Little or no expression in white matter (fimbria fornix) surrounding the hippocampus and in the corpus callosum.

Structure	Level	Pattern	Image	Note
TS26: rib	Present	Regionally restricted	9E	Expression in subset of chondrocytes of ribs and rib facet joints. Expression in small to moderate number of cells within the cartilage matrix.
TS26: perichondrium	Strong	Regionally restricted	9E	Authors report higher levels of expression expression in perichondrium surrounding ribs.

Structure	Level	Pattern	Image	Note
TS26: rib	Present	Regionally restricted	9F	Expression in small to moderate number of cells in cartilage.