Oligosaccharides - There are many types. May or may not have specific functions. Cellular metabolites - Small amounts of cellular metabolites from glycolysis, citric acid cycle, pentose phosphate shunt, RNA and DNA synthesis and fatty acid synthesis are found in milk. Also, urea, ammonia and CO2. Milk glucose levels are low when compared with lactose levels and they may reflect intracellular glucose levels.
Milk has a very low oxygen tension.
Cells - Epithelial cells sloughed off of the duct linings or off the streak canal lining in teh cow. There are very few of these in cow milk. Leukocytes including neutrophils, eosinophils, macrophages, lymphocytes. Bacterial cells including those that were in the mammary gland of a cow with mastitis and those that got into milk after it was removed from the cow. For example the AIDS virus has been shown to be passed from mother to infant via the milk.