<prompt> All of the following statements about Diploic veins are true exceptDevelop around 8th wks of gestationThese have no valvesPresent in cranial bonesHave a thin wall lined by single layer of endothelium  <response>: Diploic veins form sinuses in cancellous tissue between laminae of cranial bones.The skull is unilamellar at bih without any dipole. The diploic veins sta to develop at around 2 years of age along it diploe.These veins are lined by endothelium suppoed by some elastic tissue and are valveless.ReferenceChaurasia;s human anatomy vol 3 ,4th edition, page no.96 