Fetal and placental weight relationships in the albino rat near term.

The relationship of fetal weight to placental weight was examined in 34 albino rats on day 22 of gestation. The influence of maternal weight, fetal position and the number of fetuses in the litter and each uterine horn were assessed also. There was no indication that rats with heavier placentas had heavier or lighter fetuses.

Diploids of Clock Mutants of CHLAMYDOMONAS REINHARDI.

Diploids constructed from three clock mutants of Chlamydomonas have been analyzed. In the haploid state, these mutations all lengthen the clock period, and they are at separate genetic loci. One is recessive, one dominant, and one is probably incompletely dominant to their respective wild-type alleles.

The effect on fetal development and utero-placental blood flow of ligating a uterine artery in the rat near term.

The uterine artery of one horn of 13 rats was ligated on day 18 of gestation; the remaining horn was used as a control. The effect, four days later, on blood flow to the reproductive tract, was measured with radioactive microspheres and compared to the effect on fetal and placental weights. Fetal survival in the ligated horns, 41 percent, was significantly lower (P less than 0.

Responses to vasectomy performed at different ages in the rat.

The weights of the liver, heart and kidneys were not influenced by vasectomy at any age whereas rats vasectomized at 50 weeks gained appreciably more (30%) in body weight than their corresponding controls. Significant atrophy of the ventral prostate occurred only in the older group of vasectomized animals but this was accompanied by slight increased in circulating testosterone. Pituitary weight was unaffected by vasectomy, but slight atrophy of the testes in the 50 week old vasectomized rats might suggest the beginnings of decline in gonadal function after vasectomy in the older animals.

Ovarian venous blood flow in non-pregnant and pregnant rats.

A modified venous outflow technique was used to measure ovarian blood flow in the rat. The rate of flow through the right ovary was 0-198+/-0-009 (S.E.

Gonadal function following vasectomy in the rat.

Adult rats were studied at four, eight, and 12 months following vasectomy and sham-operation. The weights of the seminal vesicles, ventral prostate, pituitary, and kidneys were not significantly affected by vasectomy. Testicular endocrine function in vasectotomized rat was transiently stimulated as witnessed by elevation in testicular venous testosterone and androstenedione after four months.

The distribution of blood flow to the reproductive tract of anaesthetized ewes near oestrus.

Radioactive microspheres were used to measure the rate and distribution of blood flow to the reproductive tract of anaesthetized sheep. Seven sheep were examined on day 14, 6 on day 15 and 10 on day 16 of the oestrous cycle: oestrus is normally on day 16 or 17. The rate of blood flow to the myometrium, endometrium and oviducts increased by 2-fold from day 14 to 15: the weights of these organs increased on day 16.

Ovarian blood flow in conscious and anaesthetized pregnant rabbits near term and the influence of arterial blood gas tensions.

Total ovarian, luteal and stromal blood flows were measured with radioactive microspheres (25 mum diameter) in 7 rabbits anaesthetized with sodium pentobarbitone and 23 conscious rabbits at Day 28 of gestation. Despite major differences in cardiac output, arterial PO2, PCO2, pH and base status, ovarian tissue blood flows were similar in both groups. In the conscious rabbits total ovarian blood flow was negatively related to arterial pressure, and luteal blood flow was negatively related to pressure and arterial pH.

Serial measurement of arterial plasma progesterone levels throughout gestation and parturition in individual rats.

Daily blood samples were taken from 6, chronically cannulated, fully conscious rats to measure plasma progesterone levels throughout gestation. Progesterone levels in individual rats fluctuated by up to 28 ng/ml per day, but tended to be consistently higher or lower than the group mean. The accuracy of predicting progesterone levels in individual rats from previous values was examined.

The distribution of blood flow to the reproductive organs of rats near term.

The rate of ovarian and utero-placental blood flow through vessels of less than 25 mum diameter was examined with radioactive microspheres in 5 non-pregnant rats and 19 rats at Day 22 of pregnancy. Total blood flow to the reproductive organs was 0-559 ml/min in the non-pregnant animals and 13-2 ml/min in those near term, a 23-fold difference. The mean ovarian blood flow was high and increased from 0-202 ml/min to 0-845 ml/min.

Capillary blood flow to ovarian follicles, stroma and corpora lutea of anaesthetized sheep.

The radioactive microsphere technique was used to determine the rate of blood flow through vessels of up to 15 mum diameter in the ovaries of 23 anaesthetized sheep in the 72 hr preceding ovulation. The validity of the microsphere technique was established in two preliminary studies. On Days 14, 15 and 16 of the cycle the rate of blood flow (ml.

Effects of maternal blood loss on embryonic and placental development in the rat.

The effects of acute loss of maternal blood on embryonic and placental development was examined in 50 rats on Days 8 or 9 of gestation. Blood was withdrawn from conscious, cannulated rats over a 1-min period at 1-0 or 2-0 ml/100 g body weight. These degrees of blood loss were expected to produce a mild (about 50%) and severe (about 80%) reduction in uterine blood flow, respectively, for at least 15 min.