Steroid-secreting cells (luteal, thecal and interstitial cells) of the mouse ovary have been studied with the ruthenium red method to stain the ‘cell coat’. The results showed that a typical cell coat covers the entire surface of the plasma membrane except where the cells are connected by specific cell junctions. Further, particularly heavy concentration of ruthenium-red-reacting material was demonstrated in pericapillary and intercellular spaces. The differences in the thickness of the cell coat and its topographical modifications among different groups of steroidogenic cells may be related not only to intercellular adhesion and interactions but also concerned with a function of control in which the cell permeability is modified in relation with phenomena of cell recognition.
Pigments : The most common pigment in the body, besides hemoglobin of red blood cells is melanin , manufactured by melanocytes of the skin and hair, pigments cells of the retina and specialized nerve cells in the substantia nigra of the brain.  These pigments have protective functions in skin and aid in the sense of sight in the retina but their functions in neurons is not understood completely. Furthermore, cardiac tissue and central nervous system neurons shows yellow to brown pigment called lipofuscin , some believed that they have lysosomal activity. 
Animal Data: Major fetal abnormalities were observed in rabbits at 3 times human therapeutic exposure but not in rats after administration of histrelin acetate throughout gestation. There was dose-related increased fetal mortality during organogenesis in both rats given 1, 3, 5 or 15 mcg/kg/day (at less than therapeutic exposures using body surface area comparisons, based on a 65 mcg per day human dose) and in rabbits at 20, 50 or 80 mcg/kg/day (at 3 times human exposure using body surface area comparisons, based on a 65 mcg/day dose in humans).