Henk W G, Haldiman J T
Department of Veterinary Anatomy and Fine Structure, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803.
Anat Rec. 1990 Feb;226(2):187-97. doi: 10.1002/ar.1092260208.
The lungs from six bowhead whales harvested by Alaskan Eskimos have been examined with light and electron microscopes. Airways ranging from 1 to 40 mm in luminal diameter are lined by a pseudostratified ciliated epithelium containing numerous mucus-secreting cells. The underlying lamina propria-tela submucosa of these airways contains tubuloalveolar glands, plasma cells, and lymphatic accumulations in addition to both elastic and collagenous fibrillar elements. Cartilage extends to the level of the respiratory airways, but smooth muscle is absent from airways larger than 3 mm, and tubuloalveolar glands are absent from airways smaller than 3 mm. Respiratory airways are lined by pseudostratified, simple cuboidal, and simple squamous epithelia. Alveolar ducts are lined by simple squamous epithelium exclusively. A connective tissue core composed mostly of elastic fibers supports the walls of the alveolar ducts. Neither smooth muscle nor cartilage has been observed in these structures. Alveoli contain the typeical cetacean double capillary bed separated by a thick septum composed mainly of collagenous connective tissue. Alveoli are lined by a simple squamous epithelium similar to that encountered in alveolar ducts and respiratory airways. This epithelium is composed of type I and II pneumocytes closely appressed to an underlying capillary network. The type II pneumocytes contain typical lamellar bodies and tubular myelin can be seen in the air spaces. The lung is surrounded by a thick (X = 2.5 mm) visceral pleura rich in blood vessels and elastic fibers.
对阿拉斯加爱斯基摩人捕获的6头弓头鲸的肺进行了光镜和电镜检查。管腔直径为1至40毫米的气道内衬假复层纤毛上皮，含有大量分泌黏液的细胞。这些气道的固有层-黏膜下层除了含有弹性和胶原纤维成分外，还含有管泡状腺体、浆细胞和淋巴聚集。软骨延伸至呼吸性气道水平，但直径大于3毫米的气道没有平滑肌，直径小于3毫米的气道没有管泡状腺体。呼吸性气道内衬假复层、单层立方和单层扁平上皮。肺泡管仅内衬单层扁平上皮。一个主要由弹性纤维组成的结缔组织核心支撑着肺泡管的壁。在这些结构中未观察到平滑肌和软骨。肺泡含有典型的鲸类双毛细血管床，由主要由胶原结缔组织构成的厚间隔分隔。肺泡内衬与肺泡管和呼吸性气道中所见相似的单层扁平上皮。这种上皮由I型和II型肺细胞组成，紧密贴附于下方的毛细血管网络。II型肺细胞含有典型的板层小体，在气腔中可见管状髓磷脂。肺被一层厚（X = 2.5毫米）的富含血管和弹性纤维的脏胸膜所包围。
