[Histological studies of erythropoiesis in the splenic red pulp of the mouse: observations using semithin plastic sections].
In male dd-mice aged at 0, 20, 35, 70, and 150 days, erythropoiesis in the splenic red pulp was examined histologically, particularly using semithin plastic sections. In the red pulp, a majority of hemopoietic cells consist of erythroblasts. In early life until 20 days, erythroblasts constituted 91 to 96% of all the hemopoietic cells, and they then decreased gradually in proportion, although they composed 71% even at 150 days of age. The total number of erythroblasts contained in the red pulp increased in early life until it reached maximal at 35 days. At 150 days of age, erythroblasts were a half of those at 35 days in number. In semithin sections, erythroblasts were classified into two types: large erythroblasts and small erythroblasts. During life, large erythroblasts were most numerous at birth, constituting 13% of all the erythroblasts even at 150 days of age. In the red pulp, hemopoietic cells other than erythroids, such as lymphocytes, granulocytes, and megakaryocytes, were contained in relatively small numbers. Lymphocytes increased gradually in number with advancing age. In adults, macrophages were often positive in ferruginous reaction. Such macrophages were not seen in mice younger than 35 days of age.
D000367:Age Factors; D000818:Animals; D001772:Blood Cell Count; D004900:Erythroblasts / Q000166:cytology*; D004912:Erythrocytes / Q000166:cytology*; D004920:Erythropoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology; D006652:Histological Techniques; D008264:Macrophages; D008297:Male; D051379:Mice; D013154:Spleen / Q000166:cytology* / Q000648:ultrastructure