Osteoporosis is a condition in which bones become weak and prone to fractures. Women over 50 are at a high risk of developing osteoporosis which may be due to the loss of oestrogen that occurs after menopause. Over the last few decades we've learned that oestrogen plays an important role in maintaining a functional bone matrix said Tomoki Nakashima from the Tokyo Medical and Dental University (TMDU) in Japan. However how oestrogen does this was not fully understood the researchers said. In the study the researchers discovered a protein called Sema3A which was found to maintain bone matrix -- proteins