Teacher:Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Teacher: Now, understand the problem? Solve this instance: Context: The aim of this study was to describe the revascularization process of autogenous bone block grafts placed with or without an expanded polytetrafluoroethylene (e-PTFE) membrane.', 'Thirty Wistar male rats had their mandibles augmented by either an autogenous bone block graft (group A) or an autogenous bone block graft covered with an e-PTFE membrane (group B). The animals were sacrificed by perfusion at baseline, 3, 7, 14, and 21 days after surgery.', 'After 3 days, the presence of vascular sprouts derived from the recipient bed was observed in group A; more discrete sprouts were also observed in group B. After 7 days, revascularization continued, with vessels derived from both the recipient bed and the surrounding connective tissue in group A but only from the recipient bed in group B. At 14 days, group A showed penetration of vessels at the periphery of the graft; the vessels reached varying distances inside it. In group B, revascularization of the graft occurred mainly near its perforation, its borders, and at the recipient bed-graft interface. After 21 days, graft vascular penetration could be observed throughout the extent of the graft in group A but only approximately halfway through the graft in group B.
Answer: The results emphasized the importance of the vascular network and of the revascularization process of the autogenous bone graft in new bone formation. Early vascular penetration and nutrition of the graft are key factors in its integration with the recipient bed.
Student:
Does revascularization of autogenous block graft with or without an e-PTFE membrane?