15th Day Of Pregnancy Research Articles

Deposition of B Vitamins in Normally Developing Fetuses as Evidence for Increased Vitamin Needs of the Rat for Reproduction II. Pantothenic Acid and Biotin

Information has been obtained on the daily transfer of pantothenic acid and biotin from the pregnant stock rat to the developing fetuses, from the 13th day of pregnancy to parturition. The experimental animals had access to between 500 and 600 μg of pantothenic acid and 2.5 μg of biotin per day. Demands for either pantothenic acid or biotin to allow for normal development of placental tissue were small; this was especially true in the case of pantothenic acid. Fetal growth, which was most rapid between the 20th and 21st days of the gestation period, accounted for an increased need for pantothenic acid of 600 μg per day. The highest requirement for biotin occurred during the same interval of the reproductive cycle and the rate of deposition of biotin at that time exceeded 3.0 μg per 24 hours. No evidence of depletion of maternal tissues was encountered throughout the reproductive cycle.

Amount of luteal tissue required for the maintenance of pregnancy in the rat.

ConclusionsThe albino rat of the Holtz-man strain was used to determine the minimum number of corpora lutea required to maintain pregnancy. It was found 2 corpora will maintain pregnancy from the eighth day of gestation, but one corpus will not, nor will one corpus and part of another. In animals where all corpora but one were removed on the 15th day of pregnancy, two-thirds either had litters of normal fetuses or some of the fetuses were normal while others were being resorbed. All of the fetuses of the other one-third of the animals were being resorbed at the time of autopsy. Pregnancy was maintained in a group of animals in which all but 2 corpora were removed on the eighth day and hypophysectomized on the 12th day of pregnancy.There is no evidence that the placentae are adequate supplementary sources of progesterone in those groups where the corpora were reduced below two at the eighth day, since pregnancy was terminated in all cases. However, when the corpora were reduced to one on the 15th day of pr...

Pregnancy in alloxan diabetic rats.

Summary and Conclusion(1) Alloxan diabetes, like pancreatectomy diabetes, interferes with the normal oestrous cycle of rats, and impairs fertility.(2) Administration of olive oil aids in reversion of the oestrous cycle toward normal, but does not improve fertility.(3) The course of 11 of the 12 pregnancies reported in this study was uninfluenced by the presence of pre-existing permanent alloxan diabetes.(4) The course of the diabetes in 5 of the 7 rats observed was not influenced by single or repeated pregnancies.(5) Two rats died in hypoglycemia, one on the 15th day of pregnancy and one 6 days post partum. The mechanism of this hypoglycemia is unexplained.(6) Administration of insulin was not required in order to obtain live, full term litters in 10 of the 11 pregnancies observed.

Some Reactions of the Rat to Treatment with Progesterone and Estrone in Late Pregnancy.

SummaryProgesterone (2.5 mg daily) beginning on the 19th day of pregnancy in intact rats prevents labor, uterine bleeding and parturition. Estrone (25γ) started on the 19th or 20th day induces uterine bleeding, vigorous but ineffective labor and death of fetuses. Estrone (100γ) begun on the 20th day in 1 animal brought about delivery of young 1 day premature. Spontaneous delivery occurred in 4 rats given 35γ of estrone about 24 hours before time for delivery. Progesterone (2.5 mg) given simultaneously with estrone (25γ) beginning on the 20th day has the sams effect as progesterone alone, preventing the above effects of estrone alone. It is suggested that estrone plays a role in the prevention of parturition in the rat other than by way of its action on the corpora lutea.

Cell Proliferation Accelerating and Inhibiting Substances in Blood Serum During Pregnancy.

Summary1. Two types of factors which affect cell proliferation have been observed in blood serum, one of which accelerates the rate of normal cell proliferation, and the other inhibits the proliferation of normal cells. Normal blood serum contains a predominance of factcrs which accelerate the rate of normal cell proliferation. During pregnancy there is a progressive change in the balance of factors which affect cell proliferation such that the factors which inhibit proliferation of normal cells become predominant.2. The rate of cell proliferation of a cell suspension in vitro of cells obtained from rat embryos and fetuses, at least up to the 15th day of pregnancy, is accelerated by 2-amino-4-hydroxy-7-methyl pteridine and cancer blood serum and inhibited by xanthopterin and normal human blood serum.3. The rate of cell proliferation of a cell suspension in vitro, of cells obtained from rat young at the time of birth, is accelerated by xanthopterin and normal human blood serum and inhibited by 2-amino-4-hy...

THE EFFECTS OF PREGNANCY AND RELAXIN ON THE HISTOLOGY OF THE PUBIC SYMPHYSIS IN THE MOUSE

During pregnancy in the mouse the pubic bones become separated, and the gap is bridged by a ligament which at parturition may be 5 or 6 mm. long [Gardner, 1936]. The normal course of separation of the two bones in pregnant mice has been described in a previous paper [Hall & Newton, 1946a]. The bones begin to separate on the 13th day of pregnancy, and the gap widens an average of 1 mm. per day until parturition, which normally takes place during the night following the 19th day. After this the gap rapidly closes, is usually less than 2 mm. on the 3rd or 4th day post partum, but does not completely return to the virgin condition. The changes which occur during pregnancy can be produced in the spayed mouse by the administration of an extract of pregnant rabbit serum (shown by Hisaw [1926] to contain relaxin), accompanied by

Non-effect of ovariectomy on the 25th day of pregnancy in the rhesus monkey: Hartman, Carl G.: Proc. Soc. Exper. Biol. & Med.48: 221, 1941

Non-effect of ovariectomy on the 25th day of pregnancy in the rhesus monkey: Hartman, Carl G.: Proc. Soc. Exper. Biol. & Med.48: 221, 1941

STUDY OF THE GILFILLEN-GREGG SKIN TEST FOR PREGNANCY*

The present study was stimulated on the one hand by the appearance of Gilfillen and Gregg's paper describing a skin test for the detection of pregnancy, and on the other hand by Hamlett's discovery that in the monkey prolan appears in the urine for a very limited period of time, namely from the 19th to the 25th day of pregnancy. It seemed desirable to extend the study to the monkey as well as other mammals for comparison with further control observations on women. The theory underlying the Gilfillen-Gregg test is that the pregnant woman, having an abundant supply of prolan in the blood, should be immune to further injections of urinary prolan, whereas the non-pregnant woman should be prolansensitive. Their technique is as follows: Through a 26-ga. needle 2 minims of antuitrin-S is injected intradermally on the flexor surface of the forearm. Results are read a half-hour after injection. An area of erythema 25 to 30 mm. in diameter about the site of injection is considered a positive reaction and reflects the nonpregnant condition. Conversely, absence of the reaction within a half-hour is considered a positive test for pregnancy. It is claimed that the test is as reliable as that of Aschheim-Zondek, with the obvious advantages of simplicity and economy of time—an office procedure in fact.

Breathing of Amniotic Fluid as a Normal Function of Fetal Respiration

The demonstration of rhythmical respiratory movements of the fetus long before term raises the question whether or not amniotic fluid normally enters the lungs before birth as a result of these movements., , In order to determine the existence of a tidal flow of amniotic fluid in the respiratory tract, India ink was added to the amniotic fluid. In a typical experiment the uterus of a rabbit at term, i. e., 32 days, was exposed by laparotomy carried out beneath the surface of a bath of Ringer solution at 37°. General anesthesia was avoided by section of the spinal cord in the lumbar region, and inhibition of uterine contractions was obtained by injection of one cc. (100 rat units) of Antuitrin S (Parke, Davis & Co.) on the 25th day of pregnancy. The head of a fetus was distinguished readily through the transparent uterine wall. One cc. of 50% India ink was injected within the amniotic sac in the dorsal neck region between the ears. After intervals ranging from one to 60 minutes the trachea was closed by clamping the neck of the fetus. The lungs were examined and fixed in formalin before removal of the clamp. Comparison was made of the lungs of fetuses which had been showing respiratory movements with those of litter-mates in which breathing had been suppressed by injection of pentobarbital sodium. In breathing fetuses, the lungs were blackened, while in contrast in apneic fetuses the lungs were normal. Microscopical examination showed carbon particles in the alveoli of the lungs of the former but not the latter. In litter-mates which were breathing at different rates, it was found that the lungs were darker in those which showed the greater respiratory activity.

Oophorectomy and Maintenance of Pregnancy in the Rat

It is generally agreed that removal of the ovaries during pregnancy, in the rat, invariably results in the untimely interruption of this condition.- Evidence is presented in this report, however, which demonstrates that under certain experimental conditions this rule does not hold, and that the rat may carry through to term during the latter part of pregnancy in the entire absence of ovarian tissue. Adult female rats were subjected to unilateral resection of a Fallopian tube, to insure an initial litter size reduction. This was followed by exactly time mating. Laparotomy, performed on the 12th or 13th day of pregnancy, involved removal of one ovary and of foetuses in the fertile horn in excess of one. Foetal removal was so effected as to leave the placentae intact and in situ. Two days later in each instance the remaining ovary was ablated. Of 10 animals used in this series all carried to term, but failed to deliver, and the young were recovered alive after being allowed to remain in utero for one and 2 days past the expected date of parturition. Placentae, including those of previously removed foetuses, were viable and healthy. A second group of 10 females was subjected to precisely the same treatment, with the exception that the ‘extra’ placentae were included in the surgical removal of foetuses on the 12th or 13th day. Following removal of the second ovary none carried to term. Autopsy on the expected date of delivery revealed markedly involuted uteri containing no indications of embryonic substance. A control group of 11 animals, treated in the same manner with the exception that the second ovary was not extirpated, carried through successfully, and normal delivery occurred in each instance at the expected time.