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C. M. HETHERINGTON

Summary.

Intraperitoneal administration of 2-(isopropylamino) ethanol on the 3rd day of pregnancy reduces the extent of the decidual cell reaction induced by the blastocyst and can cause the death of the conceptus by the 6th day of pregnancy. Evidence is presented to support the theory that the compound administered in this way has a direct effect on the conceptus.

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C. M. HETHERINGTON

Summary.

The extent of the decidual cell reaction on the 7th day of pregnancy in uniparous mice was found to be dependent on the reproductive history of the mother. It is postulated that these observations are due to differences in the mother's immunological status.

Placental weight increased with parity but was unaffected by the sire of the first pregnancy. Fetal weight decreased with parity and there was some suggestion that the mother's immunological status may also affect fetal weight. There was also an apparent association between a reduction in decidual weight on the 7th day and a reduction of fetal weight on the 18th day of pregnancy.

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C. M. HETHERINGTON

Summary.

In random-bred Q mice, decidual weight on the 7th day of pregnancy and placental and fetal weight on the 18th day of pregnancy were compared in nulliparous and uniparous females and those which had undergone a previous pseudopregnancy with or without induction of decidual tissue by arachis oil.

The effect of parity was to increase maternal weight and placental weight but to decrease fetal weight. There was no effect on decidual weight. Pseudopregnancy with or without the induction of deciduomata failed to mimic the effects of parity on fetal weight and placental weight.

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C. M. HETHERINGTON

In the mouse at implantation, the uterus responds to the presence of a blastocyst by producing a massive cellular reaction in the stroma to form a deciduoma. The period during which the decidual cell reaction may be initiated is fairly well defined, and the reaction depends on adequate sensitization of the uterus by the ovarian hormones. In this study, two non-traumatic methods of deciduoma induction were employed, intra-luminal injection of arachis oil (Finn & Hinchliffe, 1965), and intra-luminal injection of air, which was reported by Orsini (1963) to be an effective stimulus in the hamster and the rat.

Virgin mice of the random outbred Q strain, weighing 20–25 g, and pseudopregnant after mating with vasectomized males, were used. The day on which the vaginal plug was found was taken as the 1st day of pseudopregnancy.

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C. M. HETHERINGTON

Summary.

In a series of matings between congenic strains of mice, differing at the H-2 or H-3 histocompatibility loci, decidual weight and lumbar and caudal lymph-node weight on the 7th day of pregnancy and placental and fetal weight and lumbar and caudal lymph-node weight on the 18th day of pregnancy were measured. There was no evidence that antigenic differences between mother and fetus at these loci affected any of these measurements. It was apparent, however, that there were significant differences between matings in decidual, placental and fetal weight, but not in lymph-node weight.

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C. M. Hetherington

Summary. No evidence was obtained that immunization to paternal antigens affected placental weight, fetal weight or litter size on Day 18 of pregnancy in female mice.

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C. M. HETHERINGTON

Summary.

The extent of the decidual cell reaction (DCR) on the 7th day of pregnancy and placental weight, foetal weight and placental morphology on the 18th day were found to be dependent on the genotype of the conceptus and the environment provided by the mother. No association could be found between the extent of the DCR and placental weight or placental morphology. There was, however, some suggestion of a positive association between decidual weight and foetal weight.

It is suggested that, in the presence of antigenic differences between mother and conceptus, the ability of a conceptus to elicit the DCR is impaired, or the rate of development of the decidual tissue is reduced.

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C. M. Hetherington and Helen Fowler

Summary. Placental and fetal weight was measured on the 16th day of pregnancy in normal and tolerant mice. Placental weight was increased in A mice tolerant to C57BL/10 mice only when donor cells from males were used. Fetal weight was unaffected.

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C. M. HETHERINGTON and D. P. HUMBER

Clinical Research Centre, Watford Road, Harrow

(Received 4th October 1974)

One of the most striking features of early pregnancy in the mouse is the development of the decidual cell reaction (DCR). This cellular proliferation is induced in the uterine stroma by the presence of a blastocyst on the 4th day of pregnancy (the day of finding a vaginal plug was designated the 1st day of pregnancy). The significance of the DCR and the interactions between blastocyst and uterus, which result in its induction, are poorly understood.

Kirby, Billington & James (1966) postulated that the DCR might be instrumental in preventing the rejection of the conceptus as foreign tissue. The extent of the DCR on the 7th day of pregnancy is dependent on the genotype of the mother and the genotype of the conceptus (Hetherington, 1971). Antigenic differences between mother and conceptus can apparently reduce the extent of the DCR. It

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K S Sidhu, K E Mate, T Gunasekera, D Veal, L Hetherington, M A Baker, R J Aitken and J C Rodger

The phosphorylation of tyrosine residues in cellular proteins is a major signal transduction event during sperm capacitation. In this study protein phosphorylation was monitored using a fluorescein isothiocyanate (FITC)-labeled antiphosphotyrosine monoclonal antibody and a flow cytometric procedure optimized for sperm. Using this technique, the correlation between tyrosine phosphorylation and sperm capacitation was examined in two marsupial species, the brushtail possum and the tammar wallaby and compared with that of ram spermatozoa. The levels of tyrosine phosphorylation in sperm from all three species were increased by the addition of cyclic AMP (cAMP) and vandate, a phosphotyrosine phosphatase inhibitor and were decreased by the addition of the phosphotyrosine kinase inhibitor, staurosporine. Oviductal conditioned media (CM) induced a progressive increase in tyrosine phosphorylation in both marsupial species and also induced morphological transition from a streamlined to a ‘T’-shape configuration in brushtail possum spermatozoa but not in tammar wallaby spermatozoa. Transition to the ‘T’-shape orientation associated with capacitation in marsupial spermatozoa was observed by 2 h of incubation in both species when tyrosine phosphorylation was increased by higher levels of cAMP i.e. 5 mM dibutyryl cAMP plus 3 mM pentoxyphylline. Thus the tyrosine phosphorylation trigger with CM may differ in these two marsupial species. Ram sperm tyrosine phosphorylation could be increased by addition of lower levels of cAMP (1 mM). These results support the finding that tyrosine phosphorylation is associated with sperm capacitation in marsupials. Similar results were obtained by using SDS PAGE/Western blot analysis of tyrosine phosphorylation in the brushtail possum spermatozoa. The specificity, efficiency and sensitivity of the procedure described here make it applicable for routine assessment of capacitation in large numbers of samples and in other species.