Figure 3.

Histology of spleen from conditioning start until day +21 post HSCT. Conditioning regimen resulted in decreased spleen cellularity, both in white and red pulps (D 0) compared to untreated controls (D -7). In allogeneic group, the spleen's architecture was altered and progressive hypocellularity was observed at day +5 and +7. White pulp became hardly identifiable with sparse areas of lymphocyte accumulation (A +5, A +7). Apoptotic forms were observed starting from day +5 (A+5, A +7, A +21). Uneven distribution of hematopoiesis, predominantly myelopoiesis, was observed in red pulp (A +5, A +7). Signs of partial recovery in cellularity with varying amount of lymphocytes and variable grade of hematopoiesis in red pulp was observed at day +21 (A +21). In syngeneic group, the white pulp was severely hypocellular, but red pulp showed extensive extramedullar hematopoiesis at day +5 and +7 (S +5, S +7). At day +21, the white pulp was almost re-established, only slightly hypocellular, with moderate hematopoiesis in red pulp (S +21). Day of stem cell injection is assigned as day 0 (D 0), days before and after stem cell injection are numbered with “-” and “+” sign, respectively. Hematoxylin and eosin staining, magnification ×10.