Occurrence and Importance of Glomus Organs (Hoyer-Grosser's Organs) in the Skin of the Equine and Bovine Mammary Gland

Glomus organs (Hoyer-Grosser's organs) were frequently found in the corium and the subcutis of the skin of the equine and bovine mammary gland. They were most frequently situated in the border zone between the stratum profundum and the stratum superficiale corii. These specialized vascular structures (arterio-venous anastomosis) were present in all investigated skin areas. Although the glomus organs varied in size and shape, they possessed common histologic structures: an arteriole entered the connective capsule of the glomus and divided into strongly convoluted arterio-venous channels; the arterio-venous channels united in the end to form a venule; the mentioned vascular elements were covered by a connective capsule and were thus united to an organ-like structure. Questions concerning their occurrence, their functional interpretation, their relevance, the size of the glomus organs as well as the possible involvement of the lymphatics were discussed.