The basal side, or inner surface, is tightly attached to the basement membrane, a thin layer of mostly collagen fibers that helps hold the epithelium together, and anchors it to the next-deeper layer — your connective tissue.

基底侧或内表面紧密地附着在基底膜上，这是一层薄薄的胶原纤维，有助于将上皮保持在一起，并将其固定在下一层更深的结缔组织上。

We also talked about how epithelial cells are polar, having both apical and basal sides, and are selectively permeable, and lastly we took a brief look at how our glandular epithelial tissue forms both out endocrine and exocrine glands.

我们还讨论了上皮细胞是如何极性的，具有顶端和基底两侧，并且具有选择性渗透性，最后我们简要了解了我们的腺上皮组织如何形成内分泌腺和外分泌腺。