VANESSA DE FREITAS FERREIRA

AUTHOR: VANESSA DE FREITAS FERREIRA

TITLE: MORPHO-FUNCTIONAL EVALUATION OF THE TESTICLE OF Philander frenatus (OLFERS, 1818 - DIDELPHIMORPHIA: DIDELPHIDAE)

ADVISOR:  Prof. DR. FABIANA CRISTINA SILVEIRA ALVES DE MELO

DEFENSE DATE: 09/21/2018

ABSTRACT: The knowledge of aspects and reproductive parameters of wild animals contributes to the elaboration of public policies of conservation and development of species management. This work contains two chapters. The first one presents literature review of the spermatogenic process in mammals, anatomy of the male gonad of marsupials of the Order Didelphimorphia and description of the species Philander frenatus. In the second chapter, we describe the testicular structure of Philander frenatus through morphometric and stereological analyzes. The testes of these animals have a prepenile location. As in other mammals, they are divided into tubular and intertubular compartments, have exocrine activity of sperm formation, and endocrine by the synthesis of testosterone. This androgen stimulates and coordinates the developmental stages of spermatogenesis. Sertoli cells ensure proper support and Leydig cells synthesize testosterone. This process requires a stable source of germ cells committed to developmental stages, a period of proliferation, and finally, a stage of sperm maturation. We evaluated the low values of IGS (0.17%), IPS (0.15%) and STI (0.10%), and the high values of IIS (0.07%) and PV of the interstitium in the testes (35%) indicate low gonadal and tubular body investment and high interstitial body investment. Leydig cells occupied 24.40% of the testicular volume and almost 70% of the intertubule. The mean Leydig cell volume (2627.12 μm3) is one of the highest described and probably indicates higher androgen production. Sertoli cells presented index, support capacity and number of cells per g of testis 3,91, 5,79, 2,56 x 106, respectively, which indicates low support capacity and low efficiency of S cells, result of the low investment in gamete production of this species. These characteristics are common in species that present a monogamous / polygynous mating system and aggressive and territorialistic behavior.