mesoderm

例句：

1. 1.The embryonic development of the human body is divided into three layers: the outer layer (ectoderm), the middle layer (mesoderm), and the inner layer (endoderm).
   人体的胚胎发育被分为三层：外层
2. 2. During the formation of the neural tube in the early stages of avian embryogenesis, theprimitive mesodermal tissue that will eventually form the spinal cord and brain begins to differentiate.
   在鸟类胚胎早期形成神经管的过程中，原始的中胚层组织开始分化，最终将形成脊髓和大脑。
3. 3. The mesodermal cells are responsible for producing connective tissue, which is essential for the body's structural support and protection.
   中胚层细胞负责产生结缔组织，这是身体结构支撑和保护所必需的。