Department of Ophthalmology and Save Sight Institute, University of Sydney, Australia; Australian Research Council Centre of Excellence in Vision Science, University of Sydney, Australia.
J Comp Neurol. 2014 Feb 1;522(2):435-55. doi: 10.1002/cne.23420.
The retina contains at least 30 different types of amacrine cells but not many are well characterized. In the present study the calcium-binding protein secretagogin was localized in a population of regular and displaced amacrine cells in the retina of the common marmoset Callithrix jacchus. Irrespective of their soma location, the dendrites of secretagogin amacrine cells occupy strata 2, 3, and 4 of the inner plexiform layer, between the two bands formed by cholinergic amacrine cells. Segretagogin amacrine cells are also immunopositive to antibodies against glutamic acid decarboxylase, suggesting that they use γ-aminobutyric acid (GABA) as their neurotransmitter. The spatial density of secretagogin amacrine cells decreases from a peak of about 400 cells/mm(2) near 1 mm eccentricity to less than 100 cells/mm(2) in peripheral retina; these densities account for about 1% of amacrine cells in the inner nuclear layer and for up to 27% of displaced amacrine cells. The cell bodies form a regular mosaic, suggesting that they constitute a single amacrine cell population. Secretagogin cells have varicose dendrites, which are decorated with small spines. Intracellular injection of DiI into secretagogin cells revealed an average dendritic field diameter of 170 μm and an average coverage factor of 3.2. In summary, secretagogin cells in marmoset retina are medium-field amacrine cells that share their stratification pattern with narrow-field amacrine cells and their neurotransmitter with wide-field amacrine cells. They may mediate spatial inhibition spanning the centralmost (on and off) bands of the inner plexiform layer.
视网膜中至少含有 30 种不同类型的无长突细胞，但只有少数几种得到了很好的描述。在本研究中，钙结合蛋白分泌素被定位在普通狨 Callithrix jacchus 视网膜中的一类规则和移位无长突细胞中。无论其胞体位置如何，分泌素无长突细胞的树突都占据内丛状层的第 2、3 和 4 层，位于两个由胆碱能无长突细胞形成的带之间。分泌素无长突细胞也对谷氨酸脱羧酶抗体呈阳性反应，表明它们使用γ-氨基丁酸（GABA）作为神经递质。分泌素无长突细胞的空间密度从近 1 毫米偏心度处约 400 个细胞/mm(2)的峰值下降到周边视网膜的小于 100 个细胞/mm(2)；这些密度约占内核层无长突细胞的 1%，占移位无长突细胞的高达 27%。细胞体形成规则的镶嵌，表明它们构成了单一的无长突细胞群体。分泌素细胞有静脉曲张的树突，上面有小棘。将 DiI 注入分泌素细胞内，显示出平均树突场直径为 170μm，平均覆盖率为 3.2。总之，狨猴视网膜中的分泌素细胞是中域无长突细胞，它们的分层模式与窄域无长突细胞相同，其神经递质与宽域无长突细胞相同。它们可能介导跨越内丛状层最中心（ON 和 OFF）带的空间抑制。
