Ehinger B, Bergström A, Seiler M, Aramant R B, Zucker C L, Gustavii B, Adolph A R
Eye Research Institute, Boston, MA.
Exp Eye Res. 1991 Oct;53(4):447-60. doi: 10.1016/0014-4835(91)90162-8.
Human fetal retinas (6-12 weeks post-conception) were obtained from elective abortions, transplanted to rat retinas and examined by electron microscopy. The oldest transplants that form the basis of this report were obtained 40 and 41 total weeks post-conception. The host rats were immunosuppressed with cyclosporin A. The transplants developed according to their intrinsic, genetically determined timetable. The development was heterogeneous with some parts showing almost normal differentiation and others, little. Both rods and cones developed with inner and outer segments and synaptic terminals. In regions corresponding to the inner plexiform layer, bipolar cell processes were seen in the typical dyad arrangement. Likewise, amacrine cell processes formed typical conventional synapses. Serial synapses were seen, engaging amacrine cell synapses as well as a few reciprocal synapses at the bipolar cell dyads. Monad-type synaptic complexes, a sign of immaturity, were common in bipolar cell processes. Similarly, incompletely differentiated synapses of both the amacrine and bipolar cell types were often observed. Ganglion cell processes could not be identified with certainty. A structure with morphological characteristics similar to the inner limiting membrane was noted to form inside the transplant. Both epi-retinal and sub-retinal transplants were obtained. Transplant cells touched host photoreceptor cells or pigment epithelium without any obvious specializations. The host pigment epithelium microvilli were absent adjacent to the graft. However, graft cells did appear in the host retina, and nerve cell processes were observed to cross the membrane separating the transplant and host.
人类胎儿视网膜（受孕后6 - 12周）取自选择性堕胎手术，移植到大鼠视网膜并通过电子显微镜检查。构成本报告基础的最古老移植样本取自受孕后总计40周和41周。宿主大鼠用环孢素A进行免疫抑制。移植组织按照其内在的、基因决定的时间表发育。发育情况参差不齐，有些部分显示出几乎正常的分化，而其他部分则很少。视杆细胞和视锥细胞均发育出内节、外节和突触终末。在对应于内网层的区域，可见双极细胞突起呈典型的双联排列。同样，无长突细胞突起形成典型的常规突触。可见连续突触，涉及无长突细胞突触以及双极细胞双联处的一些交互突触。单极型突触复合体是不成熟的标志，在双极细胞突起中很常见。类似地，经常观察到无长突细胞和双极细胞类型的不完全分化突触。无法确切识别神经节细胞突起。注意到在移植组织内部形成了一种具有与内界膜相似形态特征的结构。获得了视网膜上移植和视网膜下移植。移植细胞接触宿主光感受器细胞或色素上皮，没有任何明显的特化。移植部位附近没有宿主色素上皮微绒毛。然而，移植细胞确实出现在宿主视网膜中，并且观察到神经细胞突起穿过分隔移植组织和宿主的膜。
