[Effect of para-aminobenzoic acid on the development of rat embryos when applied to pregnant females].

In order to study the effects of para-aminobenzoic acid (PABA) on embryonic development, the pregnant rats were injected intraperitoneally daily with 0.3% PABA at 5 mg/kg (0.3 ml/200 g): in group 2 during the preimplantation period (days 1-6 of pregnancy), in group 3 during the period of organogenesis (days 6-16), and in group 4 during days 1-16. In group 5, PABA was injected intraperitoneally (at 15 mg/kg (0.3 ml/200 g, three times a day) during days 6-16 of pregnancy and in group 6, intragastrically as a suspension at 50 mg/kg during days 1-16. In the control (group 1), saline was injected intraperitoneally at 0.3 ml/200 g during days 1-16 of pregnancy. Autopsy of the females, counting of the number of yellow bodies and implantation sites and of the number of resorbed and died fetuses, and evaluation of development of the fetuses with an account of their mass, parieto-coccygeal size and placenta mass were performed on day 20 of pregnancy. Para-aminobenzoic acid at all tested doses does not exert a damaging effect and does not affect organogenesis. At doses 5 and 15 mg/kg, PABA does not affect growth but reduces the scattering of the extreme values of the parieto-coccygeal size and body mass, thus reflecting normalization of the growth of fetuses within the litter. At a dose of 50 mg/kg, the increase of body mass of the fetuses is insignificantly diminished (p < 0.05), which is usually normalized during postnatal development.