Department of Cellular Biology, Faculty of Biology, University of La Laguna, Avda. Fco. Sánchez s/n, 38206, La Laguna, Tenerife, Canary Islands, Spain.
Cell Tissue Res. 2011 Apr;344(1):63-83. doi: 10.1007/s00441-011-1128-3. Epub 2011 Feb 24.
Spontaneous regrowth of the axons of retinal ganglion cells (RGC) occurs after unilateral optic nerve transection (ONT) in the lizard Gallotia galloti. We have performed an immunohistochemical and ultrastructural study of the conus papillaris (CP) of this lizard during ontogeny and after ONT in order to characterize its cell subpopulations, innervation and putative blood-brain barrier (BBB) and to evaluate changes occurring throughout regeneration. Proliferating PCNA(+) cells were abundant between embryonic stage 33 (E33) and hatching. From E33, we observed Pax2(+)/GS(+) glial cells in the primitive CP, which became increasingly pigmented and vascularised from E35. Conal astrocytes coexpressing Pax2 with vimentin and/or GFAP were identified from E37-E38. GluT-1(+)/LEA(+)/Pax2(-) endothelial cells (ECs) formed a continuous endothelium with tight junctions and luminal and abluminal microfolds. In adults, the peripheral blood vessels showed a thinner calibre, stronger GluT-1 staining and more abundant microfolds than those of the central CP indicating the higher specialization involved during transport within the former. Occasional pericytes, abundant Pax2(+) pigment cells, LEA(+) microglia/macrophages, unmyelinated Tuj1(+) nerve fibres and SV2(+) synaptic vesicles were also observed in the perivascular zone. After ONT, the expression of GluT-1 and p75(NTR) persisted in ECs, suggesting the preservation/early recovery of the BBB. Relevant ultrastructural alterations were observed at 0.5 months postlesion, although, by 3 months, the CP had recovered the ultrastructure of controls indicating tissue recovery. Abnormal newly formed blood vessels had developed in the CP-optic nerve junction. Thus, the CP is a central nervous system structure whose regenerating capacity might be key for the nutritional support of regenerating RGCs in G. galloti.
在蜥蜴 Gallotia galloti 中，单侧视神经切断（ON）后视网膜神经节细胞（RGC）的轴突会自发再生。我们对该蜥蜴的视乳头圆锥（CP）进行了发育和 ON 后的免疫组织化学和超微结构研究，以鉴定其细胞亚群、神经支配和潜在的血脑屏障（BBB），并评估整个再生过程中的变化。胚胎阶段 33（E33）到孵化期间，增殖的 PCNA(+)细胞丰富。从 E33 开始，我们观察到原始 CP 中存在 Pax2(+)/GS(+)神经胶质细胞，从 E35 开始，它们变得越来越色素沉着和血管化。从 E37-E38 鉴定出共表达 Pax2 与波形蛋白和/或 GFAP 的圆锥星形胶质细胞。GluT-1(+)/LEA(+)/Pax2(-)内皮细胞（EC）形成了具有紧密连接和腔侧和基底侧微褶的连续内皮。在成年动物中，外周血管的口径较细，GluT-1 染色更强，微褶更丰富，表明前者在运输过程中涉及更高的专业化。偶尔也会观察到周细胞、丰富的 Pax2(+)色素细胞、LEA(+)小胶质细胞/巨噬细胞、未髓鞘化的 Tuj1(+)神经纤维和 SV2(+)突触小泡在血管周围区。ON 后，EC 中仍表达 GluT-1 和 p75(NTR)，表明 BBB 的保留/早期恢复。尽管在 3 个月时 CP 已恢复到对照的超微结构，但在损伤后 0.5 个月时观察到相关的超微结构改变，表明组织恢复。在 CP-视神经交界处形成了异常的新血管。因此，CP 是中枢神经系统结构，其再生能力可能是 G. galloti 中再生 RGC 营养支持的关键。
