Paranko J, Haavisto M, Chiquet-Ehrismann R, Aukhil I, Kaipia A
Department of Anatomy, University of Turku, Finland.
Differentiation. 1995 Jun;58(5):329-39. doi: 10.1046/j.1432-0436.1995.5850329.x.
The cellular mechanisms controlling sexual differentiation of fetal gonads are poorly understood. By examining the protein and mRNA expression of tenascin-C in correlation with the immunocytochemical detection of alpha-smooth muscle actin (alpha-SMA) and basement membrane heparan sulfate proteoglycan (HSPG) we demonstrate a clear-cut sex-and development-dependent expression pattern of tenascin-C in the rat testis, ovary and mesonephros. Immunocytochemistry and in situ hybridization of tenascin-C in 15-day-pc fetal testis and ovary showed protein and mRNA accumulation within the mesenchyme of the mesogonadal connection. In addition to the male and female mesonephros, some labeling could also be seen within the testicular tunica albuginea and intraovarian mesenchymal septa. In the 17-day-pc testis abundant accumulation of tenascin mRNA and protein appeared in the tunica and mediastinum testis, but not at all in the intratesticular mesenchyme. A similar pattern was still seen in the newborns where, however, a decrease in the anti-tenascin immunoreactivity of the tunica and mediastinum could be demonstrated. In contrast to the testis, expression of tenascin in 17-day-pc ovaries was widespread within the hilus and the entire intragonadal mesenchyme where it continued to accumulate also in newborns. Northern blot analysis of tenascin-C mRNAs showed one message of 8.0 kb in the 15-day-pc male and female gonads. An additional weak signal of 6.5 kb was seen in the female mesonephros. In the 18-day-pc testis, the 6.5-kb signal appeared stronger than the 8.0-kb signal. In contrast to the testis, the 6.5-kb message was weak in the developing ovary where the 8.0-kb signal had an intense peak on the day 18 pc. Further, in the ovary, mesenchymal accumulation of HSPG coincided with the spatial distribution of tenascin. In the testicular tunica and in the mesenchyme of the male and female genital ducts expression of tenascin was parallel with the differentiation of smooth muscle tissue, detected by labeling for alpha-SMA, which also indicated the tenascin-negative myoid cells of the testis. Our results indicate that tenascin expression in the fetal rat internal genitalia is involved in the differentiation of smooth muscle cells but not intratesticular myoid cells. In the ovarian mesenchyme, tenascin-C may have a specific function in the dynamic remodeling of the ovarian cords.
目前对控制胎儿性腺性别分化的细胞机制了解甚少。通过检测腱生蛋白-C的蛋白质和mRNA表达，并与α-平滑肌肌动蛋白（α-SMA）和基底膜硫酸乙酰肝素蛋白聚糖（HSPG）的免疫细胞化学检测结果相关联，我们证明了腱生蛋白-C在大鼠睾丸、卵巢和中肾中呈现出明显的性别和发育依赖性表达模式。对妊娠15天胎儿睾丸和卵巢中的腱生蛋白-C进行免疫细胞化学和原位杂交分析，结果显示在性腺系膜连接的间充质内有蛋白质和mRNA积累。除了雄性和雌性中肾外，在睾丸白膜和卵巢内间质隔中也可见到一些标记。在妊娠17天的睾丸中，腱生蛋白mRNA和蛋白质在白膜和睾丸纵隔中大量积累，但在睾丸内间质中则完全没有。在新生儿中仍可见到类似的模式，不过，白膜和纵隔的抗腱生蛋白免疫反应性有所降低。与睾丸不同，妊娠17天卵巢中的腱生蛋白表达在卵巢门和整个性腺内间质中广泛存在，在新生儿中也持续积累。对腱生蛋白-C mRNA的Northern印迹分析显示，在妊娠15天的雄性和雌性性腺中均有一条8.0 kb的条带。在雌性中肾中还可见到一条额外的6.5 kb弱信号条带。在妊娠18天的睾丸中，6.5 kb信号条带比8.0 kb信号条带更强。与睾丸相反，在发育中的卵巢中，6.5 kb条带较弱，而8.0 kb信号条带在妊娠18天时有一个强烈峰值。此外，在卵巢中，HSPG的间质积累与腱生蛋白的空间分布一致。在睾丸白膜以及雄性和雌性生殖管道的间质中，腱生蛋白的表达与通过α-SMA标记检测到的平滑肌组织分化平行，这也表明了睾丸中腱生蛋白阴性的肌样细胞。我们的结果表明胎儿大鼠内生殖器中腱生蛋白的表达参与了平滑肌细胞的分化，但不参与睾丸内肌样细胞的分化。在卵巢间质中，腱生蛋白-C可能在卵巢索的动态重塑中具有特定功能。
