Association between pig fetal measurements and gonadal development during intrauterine life

It is known that the gonadal development in fetal life is directly related to the reproductive performance of the animal in its adult life. Since some histologic testicle parameters can predict the reproductive efficiency of animals, trying to relate these parameters to fetal measurements becomes interesting to predicting the reproductive capacity of males still in uterine life. Thus, the objective was to evaluate histomorphometric characteristics of male swine testicles in different gestational ages and correlate these characteristics with fetal length and weight, and head and thorax circumference of the fetuses. Twenty one male fetuses from ten DB-90 pregnant gilts (Danbred) in three different gestational ages (50, 80 and 106 days of gestation) were used. After slaughter of gilts, the weighing of fetus and measuring of fetal length, and head and thoracic circumference was performed. For the histomorphometric analyses of the testicle, those were dissected, weighed and fixed at 5% glutaraldehyde solution and analyzes were made by the software ImageJ. The gonadal parameters were subjected to ANOVA, statistically comparing the different gestational ages using the SNK test at 5% probability. Histomorphometric variables were correlated with fetal measurements by Pearson´s correlation test. The weight of the fetal testicles and the number of Sertoli cells increased (P<0.05) throughout gestation, especially between 80 and 106 days. The weight of the gonads, the cordonal length and the number of Sertoli cells were positively correlated (P<0.01) with the weight and length of the fetus and with the perimeters of head and thorax. On the other hand, there was a negative correlation (P <0.02) between the gonadossomatic index, percentage of tubular housing and nuclear volume of Sertoli cells with fetal weights and measures. Therefore, it is concluded that cell proliferation in the fetal testis is more pronounced in the final third of pregnancy and the fetal development is directly related to fetal testicular development.