No abstract

No abstract

No abstract

A silk suture placed in the lumen of one uterine horn of rats before mating prevented pregnancy in that horn although normal implantation occurred in the unoperated horn. The suture did not interfere with fertilization or the tubal transport of ova, nor did it induce a decidual reaction; it appeared to prevent pregnancy by causing failure of implantation.

Adult female mice with an intra-uterine foreign body in one horn were mated to normal males. Females were killed on Days 2 to 11, the reproductive tracts were removed, implantations were counted and the uteri and tubes were flushed to recover unimplanted ova. None of the thirty-two females killed after Day 5 had any evidence of implantations in the operated horn, and only 28% had implantations in the control horn. Forty-five per cent of these females had an average of3 \ m=. \ 9ova in the tubes of the operated side at this time, a finding which could not be explained by any gross anatomical alteration. Fifteen animals killed prior to implantation confirmed the fact that sperm transport and fertilization did occur in both operated and control sides, but that tubal transport of ova was altered on the operated side. All of the ova remained in the tube on Day 4 when ova on the control side were recovered from the uterus.

We have previously demonstrated that human fetal epidermal melanocytes are dopa-negative. The present study was conducted to test the hypothesis that human fetal melanocytes can be activated to produce melanin under conditions differing from their natural in utero environment. To address this question, dopa staining activity of fetal epidermal sheets, obtained from seven aborted fetuses with estimated gestational ages of 13-20 weeks, was evaluated before and after engraftment on to nude mice. Dopa staining became positive 7 days post-engraftment. The intensity of the dopa reaction and the mean number of melanocytes increased by day 14 post-engraftment, and these changes were even greater by day 30. These observations indicate that human fetal melanocytes, potentially capable of synthesizing melanin under conditions differing from their normal in utero environment, are either inhibited, or not stimulated to do so.

No abstract

No abstract