{'fraction_non_alphanumeric': 0.01756511205330103, 'fraction_numerical': 0.004239854633555421, 'mean_word_length': 5.634538152610442, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The migration of lymphocytes from bone marrow to popliteal lymph nodes demonstrated by selective bone marrow labeling with 3H‐thymidine in vivo

Guinea pig popliteal lymph nodes were examined by DNA radioassay and radioautography following the selective labeling of tibial and femoral marrow cells by intramyeloid injections of 3H‐thymidine. The DNA radioactivity of the node increased for the first four days and at four to seven days exceeded that seen after an intraperitoneal injection of the same total dose of 3H‐thymidine, indicating an export of radioactivity from the labeled marrow to the node. Simultaneously, radioautographic sections of the node revealed labeled cells indicative of an origin from marrow precursors. Small lymphocytes constituted 60–90% of the labeled cells and reached maximal numbers at four to six days. Most of them were observed in the cortex, including the subcapsular sinus, primary follicles, mantle zones around germinal centers, and the lumen and walls of post‐capillary venules. However, the highest labeling indices of small lymphocytes occurred in the medulla, including the medullary cords, medullary sinuses and efferent lymphatic vessels. Labeled large mononuclear cells, including large lymphoid cells, monocytes and large blast cells, were confined almost exclusively to the cortex. A small number of labeled plasma cells was observed in the medullary cords. It is concluded that newly‐formed bone marrow lymphocytes migrate continuously into immunologically quiescent lymph nodes and become widely distributed throughout the cortex and medulla, while some enter the recirculating small lymphocyte pool.