The Histology and Histochemistry of the Circumanal Hepatoid Glands of the Dog

— —The hepatoid circumanal glands are small at birth and continue enlarging throughout life until senility. They develop as buds from the epidermis of hair follicles of the region and in the adult surround the anus in an irregular circle, development being greater in the male. The cytoplasm of the gland cell contains non-lipid, non-proteinaceous granules and there appears to be no duct system connecting gland acini to hair follicles. It is suggested that the glands may be endocrine in type. SUMMARY The hepatoid circumanal glands of the dog are bipartite as Parks concludes, composed of a major hepatoid gland element and a minor sebaceous element. However, the rigid separation into a superficial sebaceous part and lower hepatoid circumanal gland made by Parks is not apparent, the sebaceous part when present being surrounded by the hepatoid circumanal gland. Hepatoid circumanal glands develop as buds from compound hair follicles and enlarge rapidly after birth; growth continues throughout life, and is greater in the male dog where cords of cells may extend into the subcutis for some ditsance. The hepatoid glands surround the anus in an irregular circle with little or no gap between the mucocutaneous-junction and the glands. From birth the gland cells contain non-proteinaceous non-lipid granules which stain lightly with eosin. It is suggested, however, that the hepatoid gland is an endocrine gland producing secretory granules which are passed to blood vessels which are extensive in this area, and that initially they are controlled only by the pars distalis, but after puberty, by the effect of this gland on the gonads. Possibly in females androgens produced by the adrenal cortex play a part. No communication could be demonstrated between circumanal gland and follicle. At birth large sebaceous glands are present at the mucocutaneous-junction, the sebaceous glands in the hepatoid gland zone develop at the same time as the latter, but they do not increase in size after puberty. It is suggested that the sebaceous glands produce sebum which protects the epidermis. Large coiled aporcine glands intermingle with the hepatoid glands and open into the hair follicles in the region. Resume— —Les glandes circumanales hepatoides sont petites a la naissance et continuent a s'elargir durant toute la vie jusqu'a la veillesse. Elles se developpent comme des bourgeons de l'epiderme de follicules du systeme pileux de la region et chez l'adulte entourent l'anus dans un cercle irregulier, ce developpement etant plus grand chez les mâles. La cytoplasme de cellules glandulaires contient des granules sans lipides ou proteines, et il parait qu'il n'y a pas de systeme de communication, unissant les acini glandulaires aux follicules pileux. Il a ete suggere que les glandes pourraient etre de type endocrine. Zusammenfassung— —Die hepatoiden perianalen Drusen sind bei der Geburt klein. Sie werden wahrend des ganzen Lebens immer grosser bis zum Alter. Sie entwickeln sich als Keime von de Epidermis der Haarfollikel des Gebietes; beim Erwachsenen umgeben sie den Anus in einem un-regelmassigen Kreise, die Entwicklung ist grosser beim mannlichen Tier. Das Zytoplasma der Drusenzelle enthalt Kornchen, die Lipidund Proteinfrei sind. Anscheinend besteht kein Duktus-System, das die Drusen mit den Haarfollikeln verbindet. Man nimmt an, dass die Drusen endokrinen Charakter haben.