Research on the differentiation of fetal tissues by means of heterotransplantation and its application to developmental toxicology

将人类治疗性流产(妊娠32-54天)的不同器官的碎片移植到裸鼠的皮下或皮下。大多数肢体、肺和消化管的移植物被接受，并在长达18周的时间内显示出实质性的生长和组织分化。移植于睾丸内的视网膜组织容易被接受，但在皮下组织内则不能。接受器官的组织分化一般模拟活体发生。另一方面，将14日龄大鼠胚胎的肢芽切成碎片，移植到裸鼠的皮下组织中。第14天胎儿肢体间充质细胞已开始凝聚，形成软骨岛，但尚未形成软骨。移植后7天内，出现大量透明软骨，14天后开始新骨形成。20d时，破骨细胞出现，骨小梁形成，骨髓腔形成。细胞学特征：…更多的软骨细胞、成骨细胞和破骨细胞的ICS与体内看到的基本相同。许多移植物发育成长骨，有骨干和骨痂。移植的软骨和成骨过程在组织学上与体内的相应过程相似，但移植肢体的分化较慢。为了评价异种移植方法在发育毒理学中的适用性，在移植后第7、9和11天，用包括大鼠致畸物质在内的各种药物对宿主裸鼠进行了处理。移植后第20天，对移植组织进行大体观察和组织学检查。5-氟尿嘧啶、环磷酰胺、羟基脲、放线菌亚胺、丝裂霉素C、咖啡因、阿司匹林、视黄醇棕榈酸酯、全反式维甲酸和抗坏血酸可显著抑制移植物的分化。氢化可的松、四环素和沙利度胺对移植物的分化无不良影响。因此，移植的大鼠肢芽的敏感性总体上接近于体内大鼠胚胎的致畸学敏感性。胚胎组织异种移植方法可能为发育毒理学提供一种新的实验系统。较少

Pieces of various organs of human therapeutic abortuses (32-54 days of gestation) were transplanted subcutaneously or intratesticularly in athymic (nude) mice. Most grafts of the limb, lung, and digestive tube were accepted and showed substantial growth and tissue differentiation for up to 18 weeks. The retinal tissue was readily accepted when grafted in testes but not in the subcutaneous tissue. The tissue differentiation of accepted organs generally simulated that occurring in vivo.On the other hand, limb buds of day 14 rat fetuses were cut into pieces and transplanted into the subcutaneous tissue of athymic (nude) mice. In day 14 fetal limbs, mesenchymal cells have begun to condense to form cartilaginous anlage, but no cartilage has been formed. Within 7 days after grafting, masses of hyaline cartilage developed, and new bone formation began by 14 days. By 20 days, osteoclasts appeared, and the formation of bone trabeculae and marrow cavities progressed. The cytological characterist … More ics of chondrocytes, osteoblasts and osteoclasts were essentially the same as those seen in vivo. Many grafts developed into long bones, having the diaphysis and epiphysis. The mode of chondrogenesis and osteogenesis in the grafts was histologically similar to the corresponding process in vivo, although the differentiation was slower in the grafted limbs.In order to evaluate the applicability of the heterotransplantation method to developmental toxicology, the host nude mice were treated with various drugs including rat teratogens on the 7th, 9th, and llth days after grafting fetal rat limbs. On the 20th day after grafting, the grafted tissue was examined macroscopically and histologically. While control grafts showed substantial growth and tissue differentiation similar to that observed in vivo, the differentiation of grafts was significantly inhibited by the treatment with 5-fluorouracil, cyclophosphamide, hydroxyurea, cycloheximide, mitomycin C, caffeine, aspirin, retinol palmitate, all-trans-retinoic acid and ascorbic acid. Hydrocortisone, tetracycline and thalidomide did not adversely affect the differentiation of grafts. Thus, the susceptibility of transplanted rat limb buds was generally close to the teratologic sensitivity of rat fetuses in vivo. The heterotransplantation method of embryonic tissues may be useful as a new experimental system in developmental toxicology. Less