Experimental analysiss of morphogenesis of hypothalamohypophyseal system

用野生型（富含黑色素颗粒）和白化病（缺乏黑色素颗粒）蟾蜍胚胎进行移植实验，以鉴定垂体细胞的来源。神经嵴前部几乎是垂体上皮内分泌细胞的唯一来源。在神经胚开放期，垂体原基与下丘脑原基紧密并置。部分前神经脊细胞群在神经管形成后较长时间内向下丘脑迁移。其中之一是已知的LHRH神经元。但在垂体原基附着于漏斗部时，有另一种细胞群随垂体原基一起迁移并进入下丘脑前叶。虽然这些细胞没有特征，但它们极有可能分化为下丘脑神经元。因此，我们的结论是，下丘脑和垂体是在一个亲密的克隆关系。在不与下丘脑接触的垂体原基中，POMC细胞没有出现。没有垂体原基，既没有正中隆起的发展，也没有垂体神经元的延伸发生。这表明诱导垂体和下丘脑分化的刺激信号是双向的;从下丘脑到垂体，反之亦然。

Using Bufo embryos of wild type (rich in melanin granules) and of albino (devoid of melanin granules) transplantation experiments were carried out to identify the origin of the pituitary cells. The anterior part of the neural ridge was found to be the almost exclusive source of the secretory cells in the epithelial pituitary. It was also found that the pituitary primordium and the anlage of the hypothalamus are closely apposed at the open neurula stage. Some of anterior neural ridge-originated cell groups were observed to migrate into the hypothalamus long after the formation of neural tube. One of them is known to be LHRH neurons. But there is another cell group which migrates together with the pituitary primordium and penetrates into the anterior hypothalamus when the pituitary primordium attaches to the infundibulum. Although these cells are not characterized, it is highly probable that they differentiate into hypothalamic neurons. Thus, we concluded that the hypothalamus and the hypophysis are in an intimate clonal relationship. In the hypophyseal primordium developed without contact with the hypothalamus, POMC cells did not appear. Without pituitary primordium, neither development of the median eminence nor extension of hypophysiotripic neurons occurred. This indicates that stimulatory signals that induce differentiation of the hypophysis and hypothalamus are bidirectional ; from hypothalamus to the hypophysis and vice versa.