Release of luteinizing hormone-releasing hormone from enzymatically dispersed rat hypothalamic explants is pulsatile.

This study was conducted to investigate 1) the utility of a cell perifusion system to examine questions dealing with the regulation of pulsatile LHRH release and 2) the necessity of cell-cell connections for communication between LHRH neurons and for coordination of LHRH release. To this end, cell perifusion of both hemihypothalamic tissue and enzymatically dispersed hypothalamic tissue isolated from adult male rats was performed. Periodic perfusate samples were collected and assayed to measure LHRH release. LHRH release from both hemihypothalami and dispersed hypothalamic tissue was clearly pulsatile, with comparable pulse frequencies and amplitudes. These results were interpreted to support the hypothesis that coordination of pulsatile LHRH release can be maintained in the absence of most cell-cell connections. This suggests a paracrine rather than a neural mechanism for the coordination of LHRH secretory events leading to the distinct signals we observe as pulses of LHRH in situ.

Active suppression of host-vs-graft reaction in pregnant mice. VII. Spontaneous abortion of allogeneic CBA/J x DBA/2 fetuses in the uterus of CBA/J mice correlates with deficient non-T suppressor cell activity.

The mammalian fetus has been viewed as an unusually successful type of "allograft" and "unexplained" spontaneous abortion as a possible example of maternal rejection. Previous studies have shown the presence of small lymphocytic suppressor cells in the murine decidua which block the generation and reactivation of anti-paternal cytotoxic T lymphocytes (CTL) and lymphokine-activated killer cells (LAK) by elaborating a factor that inhibits the response to interleukin 2 (IL 2). A deficiency of these suppressor cells was associated with implants of xenogeneic Mus caroli embryos in the Mus musculus uterus which are infiltrated by maternal lymphoid cells and aborted. We have also shown a deficiency of such suppressor cells in the lymph nodes draining the uterus of CBA/J females in the process of aborting their semi-allogeneic CBA X DBA/2 F1 progeny. CBA/J females possess significantly lower levels of decidua-associated non-T suppressor cells on day 8.5 to 10.5 of allopregnancy than do mothers that will produce large litters of live babies. The F1 embryos are infiltrated by maternal lymphocytes prior to abortion, and the infiltration and abortion rate appears to be augmented by pre-immunization with paternal DBA/2 spleen cells. Susceptibility to spontaneous abortion is dependent upon maternal age and strain of male mate, and the high abortion rate of CBA/J mated to DBA/2 males can be reduced by immunization with BALB/c spleen cells. The CBA/J x DBA/2J mating combination provides a model of spontaneous abortion in which immunologic factors play an important role and demonstrates that the association between deficiency of decidua-associated suppressor cells and xenopregnancy failure also holds true for the failure of allopregnancies resulting from natural within-species mating.

The fate of trophoblast retained within the oviduct in the mouse.

Pre-implantation blastocysts or trophoblast, obtained from ectoplacental cones, were transferred to the right oviducts of both pregnant and nonpregnant mice. Blastocysts which remained within the oviductal lumen did not show evidence of further differentiation into trophoblast although they readily implanted on various extratubal sites. Similarly, trophoblast from ectoplacental cones failed to show invasive properties when restricted to the lumen. In 3 cases where trophoblast giant cells were found within the tubal lumen, entry appeared to have been contingent on an existing breach in the epithelium. Invasive action on tubal epithelium by trophoblast was not seen.

Dermatoglyphic traits in an Amish-Mennonite population in Ontario.

Finger- and palmprints of 63 male and 63 female Amish-Mennonites were examined for evidence of an inbreeding effect. No significant deviations were found from the general pattern seen in other populations of similar origin in terms of distribution and frequency of palmar and digital patterns, the total ridge-count, the main-line index and the maximal atd angle. Reduced correlation coefficients are reported for both the total ridge-count and the main-line index. The possibility that these reduced correlations reflect an environmental effect is discussed.