Rollins-Smith L A, Blair P
Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Dev Biol. 1990 Nov;142(1):178-83. doi: 10.1016/0012-1606(90)90161-b.
In an effort to label very early erythrocyte and lymphocyte populations and to follow their fate in normally developing postmetamorphic frogs and goitrogen-treated permanent larvae, diploid (2N) and triploid (3N) ventral blood island (VBI) mesoderm was exchanged between neurula stage embryos (about 16-22 hr old). Beginning at 15 days of age, half of the 2N or 3N hosts were treated with sodium perchlorate to prevent thyroxine-induced developmental changes. At larval stages 55-59 (41-48 days) and at 1-2 months postmetamorphosis (110-120 days), the untreated control chimeras and age-matched perchlorate-treated chimeras were killed for analysis of the VBI contribution to blood, spleen, and thymus populations by flow cytometry. The data suggest that grafting of ventral blood island mesoderm is an effective way to label an early larval erythrocyte population that declines after metamorphosis. In perchlorate-blocked permanent larvae this early VBI-derived erythrocyte population persists. In contrast, grafting of VBI mesoderm was less useful as a method to label a larvally distinct lymphocyte population in the thymus and spleen. At the late larval stages that we examined, the proportion of VBI-derived cells in thymus and spleen was not different from that observed after metamorphosis. Inhibition of metamorphosis interfered with the thymocyte expansion that normally occurs after metamorphosis, but the proportion of VBI-derived cells in thymus and spleen was not affected. This suggests that lymphopoiesis occurring in late larval life and after metamorphosis uses a stable persisting population of VBI-derived stem cells as well as dorsally derived stem cells.
为了标记非常早期的红细胞和淋巴细胞群体，并追踪它们在正常发育的变态后青蛙以及经致甲状腺肿物质处理的永久性幼体中的命运，在神经胚期胚胎（约16 - 22小时龄）之间交换了二倍体（2N）和三倍体（3N）的腹侧血岛（VBI）中胚层。从15日龄开始，将一半的2N或3N宿主用高氯酸钠处理，以防止甲状腺素诱导的发育变化。在幼体阶段55 - 59（41 - 48天）以及变态后1 - 2个月（110 - 120天），将未处理的对照嵌合体和年龄匹配的经高氯酸盐处理的嵌合体处死，通过流式细胞术分析VBI对血液、脾脏和胸腺群体的贡献。数据表明，移植腹侧血岛中胚层是标记早期幼体红细胞群体的有效方法，该群体在变态后会减少。在高氯酸盐阻断的永久性幼体中，这种早期源自VBI的红细胞群体持续存在。相比之下，作为标记胸腺和脾脏中幼体特有的淋巴细胞群体的方法，VBI中胚层的移植效果较差。在我们检查的幼体后期阶段，胸腺和脾脏中源自VBI的细胞比例与变态后观察到的比例没有差异。变态的抑制干扰了正常在变态后发生的胸腺细胞扩增，但胸腺和脾脏中源自VBI的细胞比例不受影响。这表明在幼体后期和变态后发生的淋巴细胞生成使用了稳定持续的源自VBI的干细胞群体以及背侧来源的干细胞。
