PRODUCTION OF GROWTH FACTORS BY EARLY MAMMALIAN EMBRYOS

激素和生长因子在糖尿病早期的作用 人们对哺乳动物的发育知之甚少。在过去的十年中，它 已经很明显，胚胎在发育的几个阶段会产生 生长因子，其中一些表现出转化增长的特性 因素(TGFs)。通过TGFs诱导软琼脂的能力来检测它们 未转化细胞的生长，如正常大鼠肾(NRK)细胞。 胚胎中的转化生长因子样生长因子最初是在 从妊娠中期和晚期的小鼠胚胎中提取的提取物。 最近，我们确定了从胚泡培养出来的胚胎 诱导NRK软琼脂生长的阶段释放生长因子 细胞。尽管生产这些产品的确切发展阶段 因素开始还没有确定，数据表明这些 因子由与移植后早期相关的细胞类型释放 胚胎。然而，目前还没有确定这些因素是否 在开发的早期阶段发布。此外，该检测方法 受雇的，虽然相对敏感，但不能明确地识别 所涉及的增长因素。此应用程序建议解决以下几个问题 早期发布的关于转化生长因子的重要问题 小鼠胚胎：1)它们的身份是什么？2)它们第一次是什么时候 产生的？3)它们的释放是否被干扰的条件改变 发育？4)这些因子是否由特定的胚胎组织产生？ 这些问题将通过采用一系列生物检测来解决 允许确定TGFs和相关的增长因素。这项工作 在本申请中提出的建议将有助于澄清增长的角色 在早期发育过程中的因素，并有助于决定是否进一步研究 一系列胚胎生长因子很可能产生适合于 监测植入前的正常发育。

The roles of hormones and growth factors during the early stages of mammalian development are poorly understood. During the past decade, it has become apparent that embryos at several stages of development produce growth factors, some of which exhibit the properties of transforming growth factors (TGFs). TGFs are assayed by their ability to induce the soft agar growth of non-transformed cells, such as normal rat kidney (NRK) cells. The TGF-like growth factors from embryos were initially observed in extracts prepared from mouse embryos at mid and late stages of gestation. Recently, we have determined that embryos cultured from the blastocyst stage release growth factors that induce the soft agar growth of NRK cells. Although the precise developmental stage when production of these factors begins has not been established, the data suggest that these factors are released by cell types associated with early postimplantation embryos. However, it has not been determined whether these factors are released at earlier stages of development. Furthermore, the assay employed, although relatively sensitive, could not unambiguously identify the growth factors involved. This application proposes to address several important questions concerning TGF-like growth factors released by early mouse embryos: 1) What are their identities? 2) When are they first produced? 3) Is their release modified by conditions that interfere with development? 4) Are these factors produced by specific embryonic tissues? These questions will be addressed by employing a battery of bioassays that permit the identification of TGFs and related growth factors. The work proposed in this application will help to clarify the roles of growth factors during early development and help determine whether further study of embryonic growth factors is likely to yield assays suitable for monitoring normal preimplantation development.