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. Author manuscript; available in PMC: 2007 Jun 18.

Published in final edited form as: Toxicol Pathol. 2006;34(5):425–454. doi: 10.1080/01926230600964722

Figures 3A and 3B are images of the bronchial lymph node of a control 3-month-old Sprague–Dawley rat. The trimming and sectioning of this tissue dislodged erythrocytes from congested blood vessels which then appeared in the sinusoids (Figure 3A, short arrow and Figure 3B) and in the perinodal region (Figure 3A, long arrow). Figures 3C and 3D are images of the mediastinal lymph node from a 3-month-old Wistar rat with a lesion of pulmonary hemorrhage. In this case the chronic nature of the lesion is indicated by the presence of erythrophagocytosis and hemosiderin-laden macrophages (Figure 3D). Figures 3E–H are images of lymph nodes from mice with dilated vascular spaces filled with red blood cells. In this case it is difficult to differentiate lymph node angiectasis from moderate to marked sinus erythrocytosis because dilated and blood filled lymphatic vessels can resemble dilated blood vessels. They are both lined by flattened cells and both occur throughout the lymph node. Evaluation of the other organ systems for congestion and a survey for regions of hemorrhage in the drainage field could help to more clearly define this lesion. Figures 3I–L are images of the mesenteric lymph node from a 24-month-old male B6C3F1 mouse treated with a high dose of N-methylolacrylamide. This lymph node has a range of lesions that includes nodal and perinodal angiectasia with congestion (Figures 3I–K), sinus erythrocytosis (Figures 3I–J), perinodal vascular proliferation with angiectasis and congestion (Figure 3K) and hemorrhage within the nodal parenchyma (Figure 3L). Figures 3M–P are images of the mesenteric lymph nodes from two 24-month-old male B6C3F1 mice that were treated with a high dose of methylimidazole. There are blood-filled vascular spaces (blood vessels and/or lymphatics) throughout both of the lymph nodes. There are also congested arterioles in the surrounding tissue of one lymph node (Figure 3M) and perivascular hemorrhage associated with an arteriole in the perinodal adipose tissue of the other lymph node (Figures 3O–P). Figures 3E and 3F photomicrographs are courtesy of Drs. C. Frith and J. Ward. Figures 3G and 3H photomicrographs are courtesy of Dr. Michael Leach.

Figures 3A and 3B are images of the bronchial lymph node of a control 3-month-old Sprague–Dawley rat. The trimming and sectioning of this tissue dislodged erythrocytes from congested blood vessels which then appeared in the sinusoids (Figure 3A, short arrow and Figure 3B) and in the perinodal region (Figure 3A, long arrow). Figures 3C and 3D are images of the mediastinal lymph node from a 3-month-old Wistar rat with a lesion of pulmonary hemorrhage. In this case the chronic nature of the lesion is indicated by the presence of erythrophagocytosis and hemosiderin-laden macrophages (Figure 3D). Figures 3E–H are images of lymph nodes from mice with dilated vascular spaces filled with red blood cells. In this case it is difficult to differentiate lymph node angiectasis from moderate to marked sinus erythrocytosis because dilated and blood filled lymphatic vessels can resemble dilated blood vessels. They are both lined by flattened cells and both occur throughout the lymph node. Evaluation of the other organ systems for congestion and a survey for regions of hemorrhage in the drainage field could help to more clearly define this lesion. Figures 3I–L are images of the mesenteric lymph node from a 24-month-old male B6C3F1 mouse treated with a high dose of N-methylolacrylamide. This lymph node has a range of lesions that includes nodal and perinodal angiectasia with congestion (Figures 3I–K), sinus erythrocytosis (Figures 3I–J), perinodal vascular proliferation with angiectasis and congestion (Figure 3K) and hemorrhage within the nodal parenchyma (Figure 3L). Figures 3M–P are images of the mesenteric lymph nodes from two 24-month-old male B6C3F1 mice that were treated with a high dose of methylimidazole. There are blood-filled vascular spaces (blood vessels and/or lymphatics) throughout both of the lymph nodes. There are also congested arterioles in the surrounding tissue of one lymph node (Figure 3M) and perivascular hemorrhage associated with an arteriole in the perinodal adipose tissue of the other lymph node (Figures 3O–P). Figures 3E and 3F photomicrographs are courtesy of Drs. C. Frith and J. Ward. Figures 3G and 3H photomicrographs are courtesy of Dr. Michael Leach.