15th Day Of Pregnancy Research Articles

The effect of circulating prostaglandin antibodies on reproduction in rabbits with special reference to the placenta.

Active immunization offers a fruitful approach to understanding the role of prostaglandins (PG's) in reproduction. Male and female New Zealand rabbits were immunized with PGE1, PGE2, PGFlα or PGF2α coupled either to thyroglobulin (TG) or keyhole limpet hemocyanin (KLH). Control animals were immunized with carrier TG only. Rabbits having anti-PG titers of 1:200 or greater, as determined by radioimmunoassay, were selected for study. Selected immunized males and females were mated to normal partners. All males displayed normal fertility 144 days after the initial injection suggesting normal spermatogenesis and fertilizing capacity. In females, circulating PG antibodies were ineffective in changing any steps leading to oÖgenesis, ovulation, fertilization and implantation. However, all pregnant, immunized females refused foot starting at about the 15th day of pregnancy and had vaginal bleeding as early as the 21st day. Females immunized with TG-PGF2α aborted their embryos on the 24th day while TG-PGEl, and KLH-PGE2-immunized females died suddenly without any overt signs of abortion. Postmortem examinations of these animals showed embryonic death between 12–21 days, small placentae with hemorrhage and hemorrhage and hemolysis, andlarge fatty livers in mothers. Control animals injected with carrier alone were normal in all respects. It is concluded that circulating antibodies have a profound effect on pregnant rabbits causing embryonic, and in some instances, maternal death. (Endocrinology95: 1642, 1974)

The subcellular distribution of endogenous progesterone in pregnant rat myometrium

The concentration of endogenous progesterone in the nuclear, mitochondrial, microsomal and cytosolic fractions of rat myometrium was determined during the last trimester of pregnancy and up to 20 h post partum. Progesterone was determined by a radioimmunoassay technique developed for this study. The cytosolic concentration of progesterone in the myometrium was constant from the 14–16th days of pregnancy (9–11 pmol of progesterone/mg cytosolic protein) and began to decrease after the 16–17th day. The cytosolic concentration of progesterone became low on the 21st day of pregnancy (0.5–1.0 pmol/ mg protein) and was practically the same on the 22nd day and 20 h post partum. The decrease in the concentration of endogenous progesterone in the myometrial cytosol was inversely correlated to foetal weight from the 18th to the 21st day of pregnancy. The concentration of endogenous progesterone in the microsomal, mitochondrial and nuclear fractions of rat myometrium was lower than that in the cytosol on the 14th day of pregnancy. Thereafter the concentrations of endogenous progesterone in these particulate fractions approached that of the cytosol and the amounts in the microsomal fraction exceeded the cytosolic concentration after the 18th day. Mitochondrial progesterone reached cytosolic concentrations on the 18th day of pregnancy and nuclear on the 22nd day. The concentration of progesterone decreased steeply in all fractions during the last 4 days of pregnancy and was low in every fraction on the 21st day (one day before parturition). The present results show that the ratios of endogenous progesterone concentrations in the 4 subcellular fractions studied do not vary much on a given day of pregnancy but these ratios change gradually during the last trimester of pregnancy.

Embryotoxic and transplacental oncogenic action of symmetrical dialkylnitrosamines on the progeny of rats

After administration of a single dose (by mouth) of a series of symmetrical dialkylnitrosamines (nitrosodimethylamine — NDMA, nitrosodiethylamine — NDEA, and nitrosodibutylamine — NDBA) to rats in the maximal doses tolerated by pregnant animals (NDMA, 30 mg/kg; NDEA 200 mg/kg; NDBA 1200 mg/kg), only an increase in the mortality among the embryos was observed on the 3rd, 9th, 10th, and 12th days after fertilization. No teratogenic effect likewise was observed after the intraplacental injection of NDMA and NDEA (100–300 μg into each embryonic sac) on the 13th day of pregnancy. In experiments in which the compounds were given on the 21st day of pregnancy a transplacental oncogenic effect was found in the progeny: NDMA induced tumors in 5 of 20 (25%) animals and NDEA in 15 of 31 (48%) rats that survived until the time of appearance of the first tumor. Malignant tumors were frequently situated in the kidneys.

Transport of Lead 203 and Calcium 47 From Mother to Offspring

The transfer of lead 203 (203Pb) and calcium 47 (47Ca) from mother to fetuses and litter was examined 48 hours after a single intravenous application of both radioisotopes to rats on the 18th day of pregnancy and on the fourth and 15th day of lactation. The transplacental transport of lead was eight times lower than that of calcium while the transmammary transport of lead was four times lower. The highest transfer of both radioisotopes from mother to litter was observed during the late lactation period.

Liaison du sulfate d'oestrone par les proteines seriques du rat au cours de son developpement

The binding of estrone sulfate by rat serum has been studied comparatively, with an equilibrium dialysis technique, in the embryo and the pregnant rat at the 19th day of pregnancy, as well as during post-natal development. The sera of the embryo and the new-born rat almost bind no estrone sulfate; in contrast, this binding is high in the 21-days-old and in the adult animal. A significant reduction of the affinity index is shown in the pregnant rat serum. The binding of testosterone sulfate is 3–4 times lower than that of estrone sulfate. There is no fixation of estradiol glucuronide in any of the tested sera. A positive correlation has been found between the albumin level of the different sera and their affinity index for the estrone sulfate. The albumin purified from embryo sera and the adult serum albumin have similar high affinity indexes for estrone sulfate. The binding curves for the estrogen conjugate with these two purified proteins and the whole sera of normal and pregnant adult rats are not appreciably different. In all cases, two kinds of binding sites are demonstrated: relatively strong binding sites, with an association constant of about 1.5·10 5 M −1 at 25°C and numerous low affinity binding sites, with an association constant of about 3·10 3 M −1 at 25 °C. There are probably two strong binding sites per serum albumin molecule ( n 1 ∼ 2). From these results, it is concluded that albumin is the main protein that binds estrone sulfate in the rat serum. The absence of binding in the embryo is due to the low levels of this protein and not to a qualitatively different behavior of the foetal serum albumin. The lack of binding of estrone sulfate in the embryo is in contrast with the high affinity of the embryo sera for estrone and estradiol-17β.

The plasmatic release and adrenal storage of adrenaline and noradrenaline during third part of pregnancy, parturition and post-partum in the rat

The evolution of adrenaline and noradrenaline in plasma and adrenals of rats during pregnancy, parturition and post parturition was studied. Plasmatic adrenaline demonstrated marked increases on the 18th day of pregnancy and during parturition. At the same time adrenaline stores of adrenal gland declined. Noradrenaline in plasma was significantly lower during 16th to 20th day of pregnancy and during parturition. The noradrenaline storage in adrenal gland followed nearly similar pattern as in the plasma. An accelerated rate of adrenaline release in the blood from adrenal gland during pregnancy is suggested. Noradrenaline variations appear to be the consequence of changed sympathetic nervous activity due to modifications in the endocrine status of the pregnant rats. The results suggest that variations in the concentrations of different hormones induced by the pregnancy produce altered pattern of adrenaline and noradrenaline release and storage.

Comparative affinity of embryonal and maternal serums for corticosterone and progesterone in the rat

The binding parameters of corticosterone and progesterone have been measured comparatively in the blood sera from rat, embryos and pregnant rats, at the 19th day of pregnancy. The level of corticosterone binding is significantly higher in the sera of foetal rats than in in the sera of pregnant rats. In contrast, the fixation of progesterone appears quantitatively similar in the embryo and in the pregnant rat. Scatchard analysis shows that a single protein species, with high specific affinity for corticosterone is present in the foetal as well as in the pregnant serum. The association constants have similar values, i.e.Kass= 3 to 5 × 108 M‐1 at 25 ° C; these values are characteristic for the corticosterone‐binding globulin of the rat. However, the binding capacity [concentration of binding sites (n) × number of moles of binding protein (M)] is 2 to 3 times higher in the foetal serum. The results are interpreted as indicating that the higher levels of fixation of this steroid in the embryo, compared to the mother, are due to a quantitative rather than qualitative difference between their binding proteins. The systems involved in the binding of progesterone are more complex in the embryo as well as in the pregnant rat. The values of the association constants and the results of competition and heat‐inactivation experiments suggest a probable contribution of the corticosterone binding globulin to these systems. However, the progesterone seems to bind mainly to one or several proteins with low affinity (Kass= 6 × 106 M‐1 at 25 °C) and great binding capacity (n×M= 215 × 10‐8/g of serum proteins). The foetal and pregnant rat sera appear to behave similarly in the process of progesterone binding.

The absence of any effect of maternal-fetal incompatibility at the H-2 and H-3 loci on pregnancy in the mouse.

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.

The ontogeny of aldolase in rat liver and brain

The presence of aldolases A and B in the mammalian fetal liver has been well established. In this work, we give evidence in favor of the presence in the rat fetal liver of the third known type of aldolase, aldolase C, hybridized with aldolase A. This evidence comes from :u—electrophoresis : similar anodic isozymic migration of the enzymes are observed in both brain and fetal liver.—immunology : Anti C antiserum inhibited the fetal liver aldolase activity. electrophoresis : similar anodic isozymic migration of the enzymes are observed in both brain and fetal liver. immunology : Anti C antiserum inhibited the fetal liver aldolase activity. The evolution of the three types A, B and C of aldolases from the 15th day of pregnancy to the third day after birth is characterized by a decrease of type A and C whereas type B increases up to about the same level as in the adult. The same methods show that during the same time interval, fetal aldolase in rat brain has reached the same level as in the adult with only small variations. Therefore, aldolase C in the mammalian as in the birds is present not only in the brain but also in several embryonic tissues. La présence d'aldolase A et B dans le foie fœtal de mammifères est bien établie. Dans ce travail, nous apportons des preuves de la présence dans le foie fœtal de rat du troisième type d'aldolase connu, l'aldolase C hybridée à l'aldolase A. Ces preuves sont :u—électrophorétiques : migration isozymique anodique semblable des aldolases du foie fœtal et du cerveau.—immunologiques : inhibition de l'activité aldolasique du foie fœtal par l'antisérum anti C. électrophorétiques : migration isozymique anodique semblable des aldolases du foie fœtal et du cerveau. immunologiques : inhibition de l'activité aldolasique du foie fœtal par l'antisérum anti C. L'évolution des trois types d'aldolase A, B et C du 15e jour de la gestation jusqu'au 3e jour après la naissance chez le rat se caractérise par la diminution des types A et C tandis que le type B augmente progressivement pour atteindre un niveau voisin de celui de l'adulte. L'aldolase fœtale du cerveau de rat étudiée par les mêmes méthodes pendant le même temps varie peu et reste proche de celle de l'adulte. Donc l'aldolase C, chez les mammifères comme chez les oiseaux, existe non seulement dans le cerveau mais aussi dans plusieurs tissus embryonnaires.

Placental transfer of iron in the guinea pig.

The uptake of transferrin and iron by the placenta and iron transfer to the fetuses were studied in the guinea pig using radioiodine labelled guinea pig transferrin and albumin and 59Fe. The amount of labelled transferrin bound by the placenta increased during the first 30 min after injection, then reached steady levels which were maintained for the next 60 min. No labelled transferrin or albumin was detected in the fetal blood. The rate of transfer of iron from maternal plasma to the fetuses increased after the 25th day of pregnancy to reach a maximum at about the 54th day, and then decreased markedly by the 65th day.The effects of hypoxia and of metabolic inhibitors on iron transfer were studied by in vivo perfusion of the placenta. Reduction in 59Fe transfer was observed in animals breathing 10 or 15% oxygen in nitrogen, or when sodium arsenite (5 mM), sodium cyanide (10 mM) or 2,4‐dinitrophenol (10 mM) were added to the perfusate.The results indicate that maternal plasma transferrin is an adequate source of iron for the fetal guinea pig, and that placental transfer of iron is an active process, dependent on cellular metabolism, in which maternal plasma transferrin is taken up by the placenta followed by removal of the iron from the transferrin and transfer to the fetal blood.

Connective tissue changes in the rabbit urinary bladder and ureter during pregnancy.

ABSTRACT The urinary bladder and ureters from 8 normal and 40 pregnant rabbits were studied histologically, and also by acid glycosaminoglycan analysis. No morphological changes could be demonstrated. In the later stages of pregnancy the water content was found to be lowered, and a decrease in hexosamine and uronic acid contents in bladder walls was demonstrated on the 28th day of pregnancy. It is believed that the changes are due to a hormonal influence.

Morphology of transplacentally induced neurogenic tumors in Syrian hamsters

Pregnant Syrian hamsters were given 30 mg/kg ethylnitrosurea on the 15th day of pregnancy. Among 29 newborn animals, 22 could be grown up, 14 of which developed malignant tumors. Besides tumors of the trigeminal nerve which appeared first, particularly tumors of peripheral nerves were observed. In addition one nephroblastoma and one melanoma of the subcutis were induced. There were no tumors of the brain and spinal cord. The peripheral nervous tumors showed intensive regressive changes. In general, these tumors can be classified within the group of “malignant neurinomas”.

Proliferationsdynamik des embryonalen Mäusegehirns nach fraktionierter Bestrahlung

The kinetics of cells of the embryonal mouse brain following fractionated X-ray irradiation were studied by incorporation of triated thymidine. The mice were irradiated on the 11th, 12th and 13th day of pregnancy with 60 R on the day. Microscopically no inhibition of DNA synthesis was seen. The time of mitoses was normal. Neither a reduction of mitoses nor cell death was found. The results suggest a limit of X-ray tolerance. This limit seems not to be reduced by a cumulation of X-ray.

DNA synthesis in the absence of cell reproduction during functional differentiation of mouse mammary gland

DNA synthesis, mitotic indices and DNA content of mouse mammary gland at different stages of pregnancy and lactation were determined. 3H-Thymidine specific activity of mid-pregnancy mammary gland DNA was 3 times higher than the lactating gland at its peak period of DNA replication. But, the frequency of mammary cells incorporating 3H-Thymidine was equally high in both the pregnant and lactating tissues. Consistent with its low specific activity of the DNA, the average number of silver grains per nucleus of the 6-day lactating gland was nearly 60% less than that of the pregnant mammary tissue. The nucleolus/chromatin grain ratio in the lactating tissue was significantly greater than in the mammary gland of pregnancy. In spite of the consistent rise of the labeling index between the 3rd and 6th days of lactation, the low mitotic index of the lactating gland virtually remained unaltered during this interval, whereas the high mitotic index of the pregnant tissue was proportionate to its labeling index. The total mammary tissue DNA increased significantly from the 15th day of pregnancy to the 6th day of lactation. A rise of nearly 30% per nuclear DNA content was also evident from 3 to 6 days of lactation. The results indicate that DNA synthesis in a high proportion of cells in the lactating gland may not represent premitotic DNA replication and suggest a partial replication of the cellular genome during early lactogenesis. The significance of these results with respect to “gene amplification” has been discussed.

The pontamine blue reaction in pregnant sheep uteri.

The Pontamine Blue reaction (Finn & McLaren, 1967) reflects the increased vascular permeability at the site of blastocyst attachment (Psychoyos, 1960) which presages cellular changes in the uterus associated with implantation of the embryo (Finn & McLaren, 1967; Boshier, 1968, 1969). Leakage of this macromolecular dye, therefore, precedes any modifications in uterine histology that can be associated with attachment of the embryo. The increase in vascular permeability has been considered a sine qua non for decidua formation (Psychoyos, 1961). In this study, the Pontamine Blue reaction was used (1) as confirmation of earlier observations (Boshier, 1968) that implantation in sheep occurs on the 16th day of pregnancy, and (2) to determine whether this reaction is present in sheep, a species in which there is no evidence of decidual cell formation preced¬ ing the uterine epithelial changes which occur at the implantation site (Boshier, 1968, 1969). New Zealand Romney ewes of different ages were killed 15 min after an intravenous injection, lasting over 60 sec, of that volume of a 0-5% solution of Pontamine Sky Blue 5BX in normal saline which was equivalent to 10% of the recipient's blood volume [calculated as (lb body wtx0-07 litres)/2-2]. Uteri containing extra-embryonic membranes were examined under cold normal saline, and the caruncular and inter-caruncular areas were compared for difference in colouration. Only those uteri in which there was a differentially heightened bluish colouration on the apical surface of the caruncles were regarded as showing increased vascular permeability. Table 1 shows that a positive Pontamine Blue reaction in sheep was first seen and was most frequent on the 15th day of pregnancy, but might not develop until the 16th day. These results parallel observations made in laboratory rodents (Finn & McLaren, 1967; Psychoyos, 1967). In sheep, cytological changes in the uterine epithelium associated with implantation are initiated by the blastocyst on the 16th day of gestation (Boshier, 1969). This demonstration of the Pontamine Blue reaction on the 15th day of gestation in sheep confirms (1) the observa¬ tions ofPsychoyos ( 1967) that microscopical evidence ofimplantation is apparent

Mechanisms of antifertility action of chlormadinone acetate in the rabbit.

Chlormadinone acetate was given orally in an aqueous vehicle to mature female rabbits, using a variety of dosage schedules, in a model ℌminipillℍ test. Two distinct mechanisms effective in preventing pregnancy were identified. At a dose level of 0.9 mg/kg/day, given for 3 or 4 days before artificial insemination and ovulation induction, fertilization of eggs was reduced to 12%. Continuation of the dosing for 8 days after ovulation did not alter the ED100. Acceleration of the rate of egg transport was observed whether progestin administration ceased before or after ovulation, indicating a direct effect of progestins upon the musculature of the reproductive tract. When similarly dosed animals were examined on the 15th day of pregnancy, complete inhibition of pregnancy was caused by 0.09 mg/kg/day. Investigation of the animals just prior to implantation revealed that the mechanism was compounded of accelerated egg transport, together with inhibition of blastocyst growth, shown by reduced egg recoveries and computation of blastocyst volumes, respectively. The results obtained are discussed as being analogous to the differing contraceptive mechanisms of high and low dose levels of chlormadinone acetate in the human. Comparisons are drawn between the ovulation-inhibiting action of high dose levels in human, and the fact that the high dose level used in this study (0.9 mg/kg/day) is above that needed for ovulation inhibition in the rabbit. Further similarities also exist between suboptimal ovulation inhibiting doses in the human (0.5 mg/kg/day) and in the rabbit (0.09 mg/kg/day), in that penetration of cervical mucus by spermatozoa is possible. It is suggested that inhibition of implantation may be implicated in the action of low doses of 17-acetoxy progestins in women.

Sexual receptivity in pregnant and pseudopregnant rats.

Sexual responsiveness was quantitatively assessed in female rats following a single injection of estradiol benzoate (EB) given at various times during the estrous cycle, pregnancy and pseudopregnancy. High levels of sexual receptivity were induced by 2 μg EB given during, or 1 day following, behavioral estrus in cyclic females. Sexual behavior was not observed in pregnant females treated with 2 μg EB either 3, 5, 10 or 15 days after mating; females injected immediately following insemination displayed a 2nd period of heat 48 hr later. Females given 2 μg EB on the 1st or 10th day of presudopregnancy exhibited sexual behavior; the same treatment was without effect when given on the 3rd or 5th day of pseudopregnancy. An increase in the dosage of EB to 6 ng was effectivein inducing receptivity in females treated on the 5th and 10th days of pregnancy or the 5th day of pseudopregnancy. This treatment was not effective in overcoming sexual refractoriness of females injected on the 15th day of pregnancy. Function...

Histological observations on foetal resorption in copper-deficient rats.

1. Twenty-six rats were fed a diet of milk treated with hydrogen sulphide together with copper-free mineral and vitamin supplements; fourteen of these rats were used as controls and were given 500 μg Cu per rat per week. Seven other rats were fed a commercial diet.2. Mating to stock males commenced when the rats had been fed the diets for 6 weeks, and they were killed from the 10th to the 16th days of pregnancy.3. The average number of placental sites was 17.9 in stock, 10.4 in control and 11.8 in deficient rats. Spontaneously resorbing sites were seen in three stock, seven control and six deficient animals.4. The foetuses of the stock and control animals grew normally but in the Cu-deficient rats normal development ceased on the 13th day of pregnancy when the foetal tissues were seen to be disintegrating. Necrosis of the placenta was seen on the 15th day of pregnancy and until then blood islands were present.5. Lesions were not seen in the maternal mammary glands, ovaries or pituitary glands.

Uptake of [14C]5-hydroxytryptamine by the uterus of rats treated with oestrogen and progesterone.

SUMMARY Radioactive [14C]5-hydroxytryptamine (5-HT, serotonin) creatinine sulphate was injected intrapleurally into female rats treated with oestrogen and/or progesterone which had received, immediately before the injection of 5-HT, homogenates of placenta, foetus, uterus or plasma, taken from pregnant rats on the 19th day of pregnancy. The placental homogenate produced a significant increase in 5-HT uptake by the myometrium, when the rats had been primed with moderate doses of oestrogen plus progesterone. Higher doses prevented the increased uptake, and oestrogen treatment alone did not induce 5-HT uptake. The highest level of 5-HT accumulation in the uterus was produced by placental extract after pretreatment with 0·5 mg. oestradiol plus 10 mg. progesterone/rat/day. These results suggest that the placenta contains a 'trans-serotonin' system which is dependent on the oestrogen—progesterone balance and serves to accumulate 5-HT in the placenta and myometrium. Shifts of the hormonal balance may contribute to the release of 5-HT and thus promote uterine contractions at any stage of pregnancy.

Histidine decarboxylase in mouse foetal tissues. II. Physiological role of the enzyme in delivery

Histidine decarboxylase (E.C. 4.1.1.22) activity was found to increase in mouse foetal tissues starting from the 11th day, and to reach its maximum at the end of pregnancy. The activity fell abruptly on the day preceding birth and was low in newborns. Histidine decarboxylase activity of mouse embryos was inhibited in vivo by α-hydrazino-histidine and 554-L, which are histidine decarboxylase inhibitors. Maximum inhibitory effect was observed 3 hr after administration of the inhibitors to the mother. Of the two inhibitors, the effect of 554-L was a little more intense and longer lasting. When administered towards the end of pregnancy, histidine decarboxylase inhibitors induced premature birth on the day after administration. When administered earlier than on the 18th day of pregnancy, the inhibitors were without effect of the duration of pregnancy. Induction of premature birth by α-hydrazinohistidine was due to a decrease in histidine decarboxylase activity of the foetal tissues, and not to a toxic effect of the inhibitor. The role of the decrease in histidine decarboxylase acting as a trigger for delivery of the foetus is discussed.