| Abstract: | Mechanisms were sought through which the control of preimplantation mouse embryo development by spermatozoa might be effected. A potential route for the transmission of sperm-dependent stimuli to C3HeB/FeJ females was uncovered. It was found that within 24–48 hr after artificial insemination with spermatozoa, in which the DNA had been labeled with tritiated thymidine, a minimum of 9% of the radioactivity was transported across the uterine walls. It was deposited among the maternal tissues in a pattern that differed from the patterns of isotope distribution obtained when either free tritiated thymidine or Escherichia coli cells containing DNA labeled with tritiated thymidine were used instead of labeled sper-matozoa. In sperm-treated animals the ovaries, the adrenals, and a mesenteric lymph node exhibited strikingly large accumulations of radioactivity. The heart, spleen, and uterus manifested lesser accumulations of label, but were higher than liver, kidney, lung, brain, muscle, and intestine. The specific activity of the lymph node was found to decrease during the 12–72-hr period following insemination. This result led to the hypothesis that the lymphatic system could serve as a route for the dissemination, to maternal tissues, of radioactivity originally associated with spermatozoa deposited in the uterus. Heat-inactivated spermatozoa, which have the potential for facilitating the first cleavage of fertilized embryos, exhibited a distribution pattern indistinguishable from untreated spermatozoa. Sperm protein kinase was found to survive the heat inactivation of spermatozoa. This stability was interpreted as being compatible with the kinase functioning as an intermediary in the transmission of sperm-dependent stimuli that control preimplantation embryo development in mice. |
