猫延髓吻侧腹外侧区向下丘脑室旁核和胸髓的纤维投射

THE EFFERENT PROJECTIONS OF THE ROSTRAL VENTROLATERAL MEDULLA TO THE HYPOTHALAMIC PARAVENTRICULAR NUCLEUS AND THE THORACIC CORD IN THE CAT

将WGA-HRP或荧光素Fast blue(FB)注入一侧室旁核(Pa),在双侧延髓吻侧腹外侧区(RVL)均观察到道行标记的细胞,同侧多于对侧。标记细胞从尾侧向吻侧逐渐减少。将FB注入一侧胸髓2、3节段,可见RVL逆行标记细胞从尾侧向吻侧逐渐增多,至斜方体尾侧1.0～1.5mm平面达最多,同侧多于对侧,多位于离腹面0.0～1.0mm的区域。将FB和荧光素Diamidino yellow2HCl分别注入一侧胸髓和Pa,仅在RVL观察到单标细胞,未见双标细胞。以上结果表明,Pa和胸髓分别接受起源于RVL不同细胞的纤维投射。

The efferent projections of the rostral ventrolateral medulla(RVL) to the hypothalamic paraventricular nucleus(Pa) and the thoracic cord were studied in the adult cat by using WGA-HRP or fluorescent retrograde tract-tracing method. After injection of WGA-HRP or fluorescent tracer Fast blue(FB) into one side of the Pa, retrogradely labelled cells were found in bilateral RVL, with an ipsilateral predominance. The labelled cells decreased in number from the caudal to the rostral level. After injection of FB into one side of the thoracic cord at T_2-T_3 segments, retrogradely labelled cells in the RVL were observed which increased in number from the caudal to the rostral level and reached the peak at 1.0-1.5mm caudal to the trapezoid body. Most of these cells were distributed in the ipsilateral RVL, and clustered in the region 0.0-1.0mm from the ventral surface of the medulla. After Diamino yellow 2HC1 and FB were injected into the Pa and the thoracic cord respectively, only single labelled cells were detected in the RVL, no double labelled cells were found. The above results suggest that the Pa and the thoracic cord receive separate fiber projections from different cells of the RVL.