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Abstract
Partial hepatectomy dates back to the 1800s. However, it was not determined to be an effective option to treat both benign and malignant liver disorders until recent innovations in surgical techniques. Moreover, it is considered now as a basic procedure in living donor liver transplantation.
The liver exhibits a remarkable potential to regenerate after partial hepatectomy. Advances in molecular and cell biology have revealed factors that control regeneration.
The liver and the spleen are important organs in the reticuloendothelial system and their reticulo-endothelial functions are interrelated. As the liver restores itself following partial hepatectomy, a concurrent splenic enlargement occurs and the cause of this enlargement is a matter of dispute.
The aim of this work was to study the effect of partial hepatectomy on the structure of the spleen.
Twenty four adult male albino rats were used in this study with an average weight of 130 -150 gm.
The experimental animals were classified into four groups:
-Group I: consisted of nine rats which served as a control group and animals in this group were subjected to sham operation.
The remaining three groups consisted of five rats each. The experimental animals undergone 70% partial hepatectomy following the technique described by Higgins and Anderson (1931), and then sacrificed by cervical dislocation at each of the following intervals:
-Group II: animals in this group were sacrificed three days following the operation.
-Group III: animals in this group were sacrificed seven days following the operation.
-Group IV: animals in this group were sacrificed fourteen days following the operation.
Then the spleens were dissected, weighed and divided into 2 parts; a part was dehydrated, cleared, embedded in paraffin and processed for histological & immune-histochemical staining techniques while the other part was freshly treated for formation of single cell suspension and preparation of cytospin slides, then stained by histological & immune-histochemical techniques.
Morphometric studies of the mean surface area of the lymphoid follicles and the mean number of lymphoblasts/high power field (HPF) and proliferating cell nuclear antigen (PCNA) positive cells/HPF in each group were identified. Statistical analysis was done to evaluate the morphometric data in addition to spleen weights obtained from different groups using student “t” test.
In the present study H & E stained sections revealed that there was marked distortion of the splenic architecture in group II, while in group III there were prominent periarterial lymphatic sheath (PALS). Moreover, the lymphoid follicles showed significant increase in size and the marginal zones were apparently widened. Many pale basophilic cells appeared both in the white and red pulps of both groups as well as congestion of the venous sinuses of the red pulps and thickening of the wall of the follicular artery as compared to the control group. On the other hand, group IV showed nearly similar structure as the control group except for wide marginal zones around some follicles and slight venous sinus congestion.
Prussian blue stained sections showed that hemosiderin laden macrophages were few and scattered in the red pulp of the control group, while, in groups II and III they were apparently increased in the red pulp and were evident in the white pulp as compared to the control group, whereas, group IV showed almost similar picture to the control group.
Using Wilder reticular stain, the reticular fibers in group II were apparently decreased in the white pulp with loss of fibrous network in between the cells of the red pulp as compared to the control group. While in group III, reticular fibers were decreased in the center of the lymphoid follicles with the formation of a thin delicate network in between the red pulp cells as compared to the control group. On the other hand, group IV showed nearly similar reticular fibers distribution as the control group.
Immuno-histochemically stained sections for PCNA of the control group showed few positively stained cells in the center of the follicle as well as in the splenic cord cells. While, in group II increase reaction was demonstrated in the center of the lymphoid follicles, marginal zones and splenic cord cells. In group III, the reaction was apparent in the center of the follicle and in the splenic cord cells, whereas, in group IV manifest reaction was noticed in the marginal zone with few reactions demonstrated in the splenic cord cells.
Cytospin slides stained by H & E showed the presence of many small lymphocytes in addition to few medium sized lymphocytes and lymphoblasts in the control group and group IV, whereas, in groups II and III there was statistically significant increase in lymphoblasts as compared to the control group.
Cytospin slides immune-histochemically stained for PCNA revealed few positive cells in the control group and group IV. Groups II and III showed statistically significant increase in the number of positively stained cells as compared to the control group.