Abstract
Herniation of nucleus pulposus occurs in response to injury to the annulus fibrosus of the intervertebral disc. Although Estradiol (E2) has been reported to affect the proteoglycan synthesis and water content of the cartilage, being a steroid hormone its effects on various regions of an intervertebral disc have not been widely reported. An experimental study using rabbit as a model was designed to observe the effects of E2 on stab wounded intervertebral disc ( nucleus pulposus and annulus fibrosus), in young male domestic rabbits with emphasis on changes in cell population and matrix. Study was done between an experimental and a control group. Animals in both the groups were operated upon and their intervertebral discs were injured by a surgical blade to a uniform depth. Experimental group was given an injection of E2 after the surgery. Animals were sacrificed after five (120 hrs) and seven days (168 hrs) of injury and intervertebral discs were harvested from 120 rabbits. Slides were stained with hematoxylin and eosin and alcian blue stain. Qualitative and quantitative data was recorded for the two groups. SPSS software was used for applying student. s t-test to detect significant difference (p=0.05) in the means of cell population between the subgroups. Qualitative data was recorded as percentage of observations between the subgroups. E2 increased the number of cells in the annulus fibrosus and nucleus pulposus in the experimental groups. Results suggested that recruitment of new cells into the injured intervertebral disc can be beneficial in response to injury to intervertebral disc Keywords: Annulus fibrosus. chondrocytes. Estrogen, estradiol dipropionate, intervertebral