The uropygial gland of the Southern Caracara (Caracara plancus; Falconidae: Falconinae): histological and histochemical aspects

The uropygial gland of Southern Caracara is composed of two lobes with a conical papilla and 21 tuft feathers. The RGM recorded for this species was 0.057%. The capsule surrounding the gland and the medial septum is composed of dense connective tissue and has elastic and reticular fibres. The epithelium of the adenomers can be divided into different strata: germinative, intermediate, secretory and degenerative stratum. The adenomers can be divided into three zones; from zone III, adenomers lead to secondary chambers that converge into a primary storage chamber. Histochemical techniques showed that the uropygial gland synthesizes different types of mucins and it was also positive to some lectins demonstrating the presence of a variety of glycoconjugates. The RGM in this species is smaller than that found for other Falconidae. These differences may be attributed to a negative allometric relationship. The general histological description is similar to other birds. The histochemistry and lectin histochemistry analysis showed a variety of glycoconjugates as part of the uropygial gland. Uropygial secretions have been proposed to have protective functions against bacteria and fungi. The presence of carbohydrate residues is linked to glycoconjugates with antimicrobial functions in many vertebrates associating our results with this species′ habits.