1. 20 Canalicular stage (13-14wks): The respiratory bronchioles developed quickly, the primitive alveoli had developed, the respiratory bronchioles were lined by cuboid cells.

2. The differential diagnosis of canalicular adenoma, basal cell adenoma and basal cell adenocarcinoma, adenoid cystic carcinoma, polymorphous low-grade adenocarcinoma, myoepithelial tumors, epithelial-myoepithelial carcinoma, and basaloid squamous cell carcinoma is discussed.

3. Several reproducible differences in polypeptide patterns were observable between the two membrane fractions; in particular, components possibly corresponding to the heavy chain of myosin and to actin were prominent in the bile canalicular membrane fraction.