Response to injury and estrogen in vertebral epiphyseal plates and end plates

Although estradiol (e2) has been reported to affect the proteoglycan synthesis and water content of the cartilage,its effects on epiphyseal and end plates of the intervertebral disc have not been widely explored. an experimental study using rabbit as a model was designed to observe the effects of estradiol on the epiphyseal plate and end plate of stab wounded intervertebral disc of young male domestic rabbits,with emphasis on changes in cell population and matrix. it was conducted at the department of anatomy,college of physicians and surgeons pakistan,regional center,islamabad. animals in the control and experimental groups were operated upon and their intervertebral discs were injured to a depth of 4mm. experimental group was given 5mg/kg intramuscular injection of e2 after the surgery. animals (n=120) in control and experimental groups were sacrificed after five (120 hrs.) and seven days (168 hrs.) of injury and intervertebral discs were harvested from both groups (n=60).10μm thick sections were stained with hematoxylin,eosin and alcian blue stain. quantitative and qualitative data was recorded for the groups. e2 increased mitosis of chondrocytes significantly in epiphyseal plate. the end plate did not show a significant response. the results suggest that therapeutic administration of e2 can be mitogenic and may recruit cells to the intervertebral disc in response to injury which may have an effect on its response to injury and subsequent healing.