Effects of castration on early postnatal development of male accessory sex glands in the domestic pig

Department of Biomedical Sciences, University of Guelph, Ontario, Canada.

In the neonatal pig there is a remarkable production of steroids by the testes for the first few weeks after birth. Several androgens and estrogens reach a peak at about one month of age. In order to gain an understanding of the significance of this early steroid secretion we examined the effect on accessory sex glands of removal of the testes before the peak in these compounds would have occurred. Pigs were castrated (n = 38) at 2-3 weeks of age, with littermates serving as intact controls (n = 33). Animals were killed at ages ranging from 4-12 weeks. Blood samples were taken and both bulbourethral (BU) and vesicular glands (VG) were removed, as well as the testes of intact males. Organ pairs were weighted and samples fixed for histological examination. Plasma samples were stored at -20 degrees C until assayed, without extraction, for testosterone, dehydroepiandrosterone sulfate (DHEAS) and estrone sulfate (E1S) by radioimmunoassay. Of the hormones measured, plasma DHEAS concentrations were highest, but variable over the time period (304.2 and 75.6 nmol/l; 87.7 and 21.8 ng/ml at 5 and 12 weeks respectively). E1S declined steadily from 76.6 to 5.8 nmol/l (20.7 to 1.56 ng/ml). Testosterone levels were lowest but rose from 2.67 to 9.54 nmol/l (0.77 to 2.75 ng/ml). No steroids were clearly detectable in samples from castrated males. Testes weights (wt) increased fourfold, as did body wt for both intact and castrate males. Both BU and VG showed absolute increase in wt (3.5x and 5x respectively) in intact males, and each was about 2.8x greater than in castrates (mg/kg body wt). Histological sections were markedly distinctive for both BU and VG between intact and castrate animals, and a lack of developmental changes in both glands was noted in the castrates. Our findings provide clear evidence of an influence of the testes on accessory sex glands in the early postnatal life of the pig.

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