Cohen W D, Cohen M F, Tyndale-Biscoe C H, VandeBerg J L, Ralston G B
Department of Biological Sciences, Hunter College of C.U.N.Y., New York.
Cell Motil Cytoskeleton. 1990;16(2):133-45. doi: 10.1002/cm.970160207.
Seeking to resolve conflicting literature on cytoskeletal structure in mammalian "primitive" generation erythrocytes, we have utilized the circulating blood of developing marsupials. In young of the Tammar Wallaby (Macropus eugenii) and the Gray Short-tailed Opossum (Monodelphis domestica), relatively large, nucleated primitive erythrocytes constituted nearly 100% of the circulating population at birth (= day 0) and in fetuses (Tammar) several days before birth. These cells were discoidal or elliptical, and flattened except for a nuclear bulge. Their cytoskeletal system, consisting of a marginal band of microtubules enclosed within a cell surface-associated network (membrane skeleton), closely resembled that of non-mammalian vertebrate erythrocytes. By day 2 or 3, much smaller anucleate erythrocytes of "definitive" morphology, lacking marginal bands, appeared in abundance. These accounted for greater than 90% of the circulating population of both species by day 6-8. Non-nucleated erythrocytes of a different type, constituting 1-6% of the cells in most blood samples up to day 7, were identified as anucleate primitives on the basis of size, shape, and presence of a marginal band. Thus, loss of erythrocyte nuclei in mammals appears to begin earlier than generally recognized, i.e., in the primitive generation. Counts of these anucleate primitives in young of various ages implicated nucleated primitives as their probable source. Pointed erythrocytes, occasionally found in younger neonates of both species, occurred in greatest number in fetuses (Tammar) prior to birth. This is in accord with previous work on non-mammalian vertebrates suggesting that such cells are morphogenetic intermediates. The results confirm the long-suspected similarity between mammalian primitive erythrocytes and the nucleated erythrocytes of all non-mammalian vertebrates.
为了解决有关哺乳动物“原始”代红细胞细胞骨架结构的相互矛盾的文献，我们利用了发育中的有袋动物的循环血液。在塔马尔袋鼠（Macropus eugenii）和灰短尾负鼠（Monodelphis domestica）的幼崽中，相对较大的有核原始红细胞在出生时（=第0天）和出生前几天的胎儿（塔马尔袋鼠）中几乎占循环红细胞总数的100%。这些细胞呈盘状或椭圆形，除了核凸起外均扁平。它们的细胞骨架系统由微管边缘带组成，包裹在细胞表面相关网络（膜骨架）内，与非哺乳动物脊椎动物的红细胞非常相似。到第2或3天，大量形态“确定”的小得多的无核红细胞出现，这些红细胞缺乏边缘带。到第6 - 8天，它们在这两个物种的循环红细胞总数中所占比例超过90%。在大多数血液样本中，直到第7天，另一种类型的无核红细胞占细胞总数的1 - 6%，根据大小、形状和边缘带的存在，它们被鉴定为无核原始红细胞。因此，哺乳动物红细胞核的丢失似乎比普遍认为的更早开始，即在原始代。对不同年龄段幼崽中这些无核原始红细胞的计数表明有核原始红细胞可能是它们的来源。在这两个物种的较年幼新生儿中偶尔发现的尖头红细胞，在出生前的胎儿（塔马尔袋鼠）中数量最多。这与之前关于非哺乳动物脊椎动物的研究结果一致，表明这些细胞是形态发生中间体。结果证实了长期以来人们所怀疑的哺乳动物原始红细胞与所有非哺乳动物脊椎动物的有核红细胞之间的相似性。
