PARENT SESSION

(M193) TESTIS STRUCTURE, DURATION OF SPERMATOGENESIS AND SPERMATOGENIC AND SERTOLI CELL EFFICIENCIES IN THE COLLARED PECCARIES (Tayassu tajacu).

Franca, Luiz¹, Leal, Marcelo¹, Pimenta, Leandro¹, Chiarini-Garcia, Helio¹, Silva, Jurupytan², Guimaraes, Diva², ¹ Federal University of Minas Gerais, Belo Horizonte, MG, Brazil² Federal University of Para, Belem, PA, Brazil

ABSTRACT- The collared peccary is the only wild ungulate of the Western Hemisphere and has a yearlong breeding season. Due to the good flavor and the low cholesterol content of its meat this species presents potential economical interest. However, its reproductive biology remains largely unknown and data related to the testis structure and function for this species are still scarce. In this regard, the present study was performed to investigate the testis structure, spermatogenic cycle length and the spermatogenic and Sertoli cell efficiencies in sexually mature peccaries. Twelve animals from an Amazonic Research Center were utilized. To estimate the cycle length three animals received intratesticular ³H-Thymidine injections 1h and 21d before orchiectomy. Testes tissue was fixed by immersion with 4% glut. and embedded in plastic and routinely prepared for histomorphometric analysis. The mean body and testis weight in peccaries was 23kg and 24g. The volume density of Leydig cells (LC) and seminiferous tubules (ST) was 13% and 77%, respectively. The mean ST diameter was 255micrometer, whereas the total length of ST per testis was 320 meters (15m/g). LC in peccaries have a peculiar morphology and a cord-like organization and its individual volume was 1170 cubic micrometer. LC and Sertoli cells number per gram of testis and per testis was 120 x 10⁶ and 28 x 10⁶; and 25 x 10⁸ and 5.8 x 10⁸, respectively. According to germ cell associations, eight stages of spermatogenesis were characterized. From their relative frequencies and the most advanced germ cells labelled at 1h and 21d after thymidine injection, each spermatogenic cycle and the spermatogenic process (based in 4.5 cycles) was estimated to last 12 and 55 days, respectively. Eleven spermatids were found per Sertoli cell at stage 1 of the cycle and 24 millions of spermatids were daily produced per testis gram (DSP/g). Based on several parameters investigated, such as the characterization of the stages of the cycle, pre- and post-meiotic stages frequencies and spermatogenic efficiency (DSP/g), spermatogenesis in peccaries is very similar to that described for domestic pigs and wild boars, which are species phylogenetically related to peccaries. Financial support: CNPq, CAPES, EMBRAPA and FAPEMIG.

KEY WORDS: testis, spermatogenesis, morphometry, collared peccary