Lipoprotein mesophase

Table I. Properties of Lipoprotein Mesophase of Atheromatous Tissue...

The normal ovarian and adrenal lipid is intracellular, but there is another important situation in which a lipoid mesophase may be present more or less normally, entirely outside cells. This is in the plasma (39), in the low density /3-lipoprotein fraction (Sf 12 to 20). In health, this fraction is low or absent until adult life. It begins to increase in males from about the age of 20 onward in females, it remains low until the menopause, after which it increases rapidly as in males. It can be produced experimentally in rabbits, dogs, fowls, and some other animals by feeding cholesterol. Analogous to this is the pathological increase seen in humans with certain renal and metabolic disorders, especially in diabetes mellitus and in hereditary or essential hyperlipemia, where there is an increase in several fatty components in the blood, with abnormal deposition of fat in various tissues. 

Before (A) and 5 minutes after (B) injection of heparin intravenously. Marked increase in birefringence in B is caused by aggregation of lipoprotein in mesophase. 

The progesterone-secreting corpus luteum cells of the ovary also contain a mesophase similar in form, properties, and composition to that of the lowest density lipoprotein of plasma, and of the early atheroma deposits. Superficially, it might seem that women keep the mesophase in the cyclically forming corpora lutea while men let it circulate and thence deposit itself in arteries women begin to do this only when they reach the menopause and no longer form corpora lutea. This may simply be a localized expression of the fact that fat distribution is fundamentally different... 

---