MORPHOLOGICAL DESCRIPTION OF THE MAMMARY GLAND OF XERNATHRANS
Acini; Epithelium; Mammary embryology; Common sloth; Anteater; Armadillo; Preservation
Xenarthra group comprises Anteaters, Sloths, and Armadillos, widely known species in Brazil. However, the morphology of their mammary gland is still poorly explored. This study aimed to characterize the mammary gland morphology in Tamandua tetradactyla, Bradypus variegatus, and Dasypus novemcinctus. All animals used in this study were provided cryopreserved to the Animal Morphological Research Laboratory (LaPMA) from the Bauxite Mine in Paragominas, Pará, in accordance with SEMA-PA authorizations No. 455/2009 and 522/2009. Collected samples were preserved in 10% formaldehyde solution and subsequently embedded in paraffin blocks. Sections were stained with Hematoxylin and Eosin (HE). The morphometric study of Tamandua tetradactyla revealed that the average height of the right mammary papillae was 2.8 cm, like the left mammary gland (2.3 cm). For Bradypus variegatus, the average height of the nipple in the right gland was 0.8 cm, while in the left gland, it was 0.95 cm, with slight variation. Dasypus novemcinctus showed limitations in papillary height measurement but indicated symmetrical consistency in mammary gland size. In light microscopy, Tamandua tetradactyla specimens exhibited a simple stratified epithelium with a thin layer of keratin, dense connective tissue, hair follicles, and limited glandular tissue. Bradypus variegatus displayed pavement cells, a thin corneal layer, dense connective tissue, collagen fibers, blood vessels, nerves, and smooth muscle around the glandular structure. For Dasypus novemcinctus, a keratinized stratified simple epithelium, modeled connective tissue, hair follicles, and underdeveloped alveoli with no secretions in the papillary lumen were observed. These histological features highlight the morphological similarity of mammary glands in the studied species.