An embryo-like model researchers created from stem cells can provide a 'blueprint' of the human body as it forms, a study has reported.

The development by researchers from the University of Cambridge will allow experts to study the so-called 'black box' period of human development, gastrulation.

Scientists are unable to directly observe this time in human development in the laboratory as a result of ethical and legal constraints on embryonic research.

The model may help reveal the causes of birth defects or diseases that begin during gastrulation and are often linked to alcohol, medications, chemicals and infections.

A better understanding of the gastrulation period in humans could also help shed light on other conditions including infertility, genetic disorders and miscarriage.

'Our model produces part of the blueprint of a human,' said paper author and geneticist Alfonso Martinez-Arias of the University of Cambridge.

'It's exciting to witness the developmental processes that until now have been hidden from view — and from study.'

This 'black box' period, known as gastrulation, had previo