4

3

1

2

Make and secrete uncalcified extracellular matrix

Maintain the calcification of bone matrix over a period of time

Breakdown and resorb calcified extracellular matrix

Inner cell mass

Endoderm

Neuron

Zygote

Erythrocytes

Eosinophils

Basophils

Neutrophils

Centrally placed nuclei

Few mitochondria

Intercalated discs

Syncytial fibres

Arise from haematopoietic stem cells

Develop from mesodermal osteoprogenitor cells

Differentiate from chondrocytes during ossification

Develop from neural crest-derived cells

They only undergo symmetrical division to produce more stem cells

They are terminally differentiated into a specific cell type

They divide several times before differentiating

They can divide without limit, and undergo asymmetric division

Extravillous trophoblasts

Cytotrophoblasts

Luminal epithelium

Decidual cells

Transfer of the nucleus of the skin cells into an enucleated somatic cell

Growing skin cells in cell culture

Expression of four key transcription factors in the skin cells

Transfer of cells from the inner cell mass from a blastocyst into culture

Paracrine signalling from myocyte to growth cone

Contact dependent as they are attached to the muscle cells

Synaptic signalling by release from the axon terminal

Endocrine signalling as neurotrophins are widely dispersed