Physiology, Endocrinology, and Reproduction II

Birds of prey have an important role in maintaining the populations of small animals, helping to keep the ecological balance in the regions they inhabit. The Snail Kite (Rostrhamus sociabilis) is a bird from the Falconiforme order, Accipitridae family, which also comprises vultures, eagles and hawks. It is a diurnal bird found in the freshwater wetlands of Central and South America, Caribbean and southern United States. Although it is rated as Least Concern by Bird Life International, in Florida the species is locally endangered due to the water level control in the Everglades: the draining resulted in a decrease in the number of apple snails, the main element of its diet. The objective of this work was to study the testes of the Snail Kite, aiming to obtain knowledge about its reproductive cycle in southern Brazil. In October, one adult Snail Kite male was brought to the Wildlife Rehabilitation Center from the Federal University of Pelotas, presenting an exposed fracture in the distal portion of the humerus. The bird was euthanized one day after its arrival, and the testicles were collected for histology. The testes were placed in 10% buffered formalin; after fixation they were dehydrated in 7 crescent concentrations of alcohol (70, 80, 90, 96, 96, 100, and 100%), immersed 3 times in xylol at 100%, impregnated and included in Paraplast Xtra, and sliced (5 μm) in rotating microtone. To observe all the structures, different cuts from the same testis were stained with one of 4 colorations: Harris Hematoxylin and Eosin (HE), which stains cells nuclei and cytoplasm; Mallory trichrome, which stains connective tissue; Gomori trichrome, which stains muscle tissue, and Periodic Acid Schiff + HE, which stains carbohydrates present in basal lamina. When observed at optical microscope, the testes cuts showed a multi stratified epithelium containing sperm in different stages of development, as well as polygonal Sertoli cells, indicating intense seminiferous tubules activity. These results show that in October, the bird was in the reproductive season, with the testes fully functional and producing sperm with normal morphology.