Detailed morphological characterization of testicular leukocytes in the adult CX₃CR₁^gfp/+ transgenic mouse identified two distinct CX₃CR₁⁺ mononuclear phagocyte (macrophage and dendritic cell) populations: stellate/dendriform cells opposed to the seminiferous tubules (peritubular), and polygonal cells associated with Leydig cells (interstitial). Using confocal microscopy combined with stereological enumeration of CX₃CR₁^gfp/+ cells established that there were twice as many interstitial cells (68%) as peritubular cells (32%). Flow cytometric analyses of interstitial cells from mechanically-dissociated testes identified multiple mononuclear phagocyte subsets based on surface marker expression (CX₃CR₁, F4/80, CD11c). These cells comprised 80% of total intratesticular leukocytes, as identified by CD45 expression. The remaining leukocytes were CD3⁺ (T lymphocytes) and NK1.1⁺ (natural killer cells). Functional phenotype assessment using CD206 (an anti-inflammatory/M2 marker) and MHC class II (an activation marker) identified a potentially tolerogenic CD206⁺MHCII⁺ sub-population (12% of total CD45⁺ cells). Rare testicular subsets of CX₃CR₁⁺CD11c⁺F4/80⁺ (4.3%) mononuclear phagocytes and CD3⁺NK1.1⁺ (3.1%) lymphocytes were also identified for the first time. In order to examine the potential for the immunoregulatory cytokine, activin A to modulate testicular immune cell populations, testes from adult mice with reduced activin A (Inhba^+/−) or elevated activin A (Inha^+/−) were assessed using flow cytometry. Although the proportion of F4/80⁺CD11b⁺ leukocytes (macrophages) was not affected, the frequency of CD206⁺MHCII⁺cells was significantly lower and CD206⁺MHCII⁻ correspondingly higher in Inha^+/− testes. This shift in expression of MHCII in CD206⁺ macrophages indicates that changes in circulating and/or local activin A influence resident macrophage activation and phenotype and, therefore, the immunological environment of the testis.

成年 CX ₃ CR ₁ ^gfp/+转基因小鼠睾丸白细胞的详细形态特征鉴定了两种不同的 CX ₃ CR ₁ ⁺单核吞噬细胞（巨噬细胞和树突细胞）群体：与生精小管（管周）相对的星状/树状细胞和与 Leydig 细胞相关的多边形细胞（间质）。使用共聚焦显微镜结合 CX ₃ CR ₁ ^{gfp/+ 的}立体计数细胞确定间质细胞 (68%) 是管周细胞 (32%) 的两倍。来自机械分离的睾丸的间质细胞的流式细胞术分析基于表面标记物表达（CX ₃ CR ₁、F4/80、CD11c）鉴定了多个单核吞噬细胞亚群。这些细胞占总睾丸内白细胞的 80%，如 CD45 表达所确定的。剩余的白细胞是 CD3 ⁺ (T 淋巴细胞) 和 NK1.1 ⁺ (自然杀伤细胞)。使用 CD206（一种抗炎/M2 标记物）和 MHC II 类（一种激活标记物）进行的功能表型评估确定了一个潜在的致耐受性 CD206 ⁺ MHCII ⁺亚群（占总 CD45⁺细胞）。CX ₃ CR ₁ ⁺ CD11c ⁺ F4/80 ⁺ (4.3%) 单核吞噬细胞和 CD3 ⁺ NK1.1 ⁺ (3.1%) 淋巴细胞的罕见睾丸亚群也首次被鉴定。为了检查免疫调节细胞因子、激活素 A 调节睾丸免疫细胞群的潜力，使用流式细胞术评估了激活素 A降低 ( Inhba ^+/- ) 或激活素 A ( Inha ^+/- )升高的成年小鼠的睾丸。虽然 F4/80 ⁺ CD11b ⁺白细胞（巨噬细胞）的比例没有受到影响，但 CD206 ⁺在Inha ^+/-睾丸中，MHCII ⁺细胞显着降低，CD206 ⁺ MHCII ^-相应地更高。CD206 ⁺巨噬细胞中 MHCII 表达的这种变化表明循环和/或局部激活素 A 的变化影响驻留巨噬细胞的激活和表型，从而影响睾丸的免疫环境。