separating的逻辑主语是谁？

The lung has a well-developed lymphatic system draining the interstitial space through a network of channels around the bronchi and pulmonary vessels towards the hilum. Lymphatic vessels are seen in the juxtaseptal alveolar region (see later discussion) and are commonly found in association with bronchioles. Down to airway generation 11 (see Table 1.1), the lymphatics lie in a potential space around the air passages and vessels, separating them from the lung parenchyma. In the hilum of the lung, the lymphatic drainage passes through several groups of tracheobronchial lymph glands, where they receive tributaries from the superficial subpleural plexus. Most of the lymph from the left lung usually enters the thoracic duct, whereas the right side drains into the right lymphatic duct.

肺的淋巴系统很发达，通过支气管和肺血管周围的网络状淋巴通道，将间质液引流至肺门。淋巴管见于肺泡旁区域（见后面的讨论），常与细支气管伴行。直到第11级细支气管（见表1.1），淋巴管一直位于气道和血管周围的潜在空间中，淋巴管将潜在空间与肺实质分开。在肺门，胸膜下浅丛的淋巴液引流到几组气管支气管淋巴腺。来自左肺的大部分淋巴液通常进入胸导管，而右侧淋巴液流入右侧淋巴管。

separating的逻辑主语是谁？是the lymphatics？

them指谁？potential space？