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R. M. MOOR and R. G. CRAGLE

Summary.

A total of 429 eggs was used to investigate procedures both for the removal of the zona pellucida and for the culture of sheep eggs in vitro.

The effect of pronase, papain, bromelain, trypsin and α-chymotrypsin, on the zonae pellucidae of fertilized and unfertilized eggs was studied in the first series of experiments. All the enzymes were effective in removing the zonae pellucidae from unfertilized eggs. Pronase was the only enzyme that had a significant lytic effect on the zonae of fertilized eggs denuding 34% of eggs in less than 5 min and almost all the other eggs within 90 min.

Investigation of some of the factors involved in the successful culture of normal sheep eggs in vitro constituted the second part of the study. Eggs of both the eight- to sixteen-cell and morula stages were cultured for 72 hr in either sheep serum, enriched tissue culture medium 199 or Brinster's medium. The development and viability of the eggs after culture was determined by transferring some eggs to recipient sheep and making accurate cell counts on the remainder. Eggs recovered at the eight-cell stage underwent only one or two cleavage divisions during the 72-hr culture period. These eggs did not develop into foetuses when transferred to the uteri of recipient sheep. On the other hand, the majority of morulae cultured for 72 hr in enriched M199 or sheep serum underwent cleavage and blastulation in vitro. That the cultured blastocysts were normal was demonstrated by their implantation and growth into foetuses when transferred to the uteri of suitable recipients.

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R. K. Johri and P. R. Dasgupta

Summary. An intrauterine copper device stimulated endogenous hydrogen peroxide formation in whole homogenates and in the mitochondrial and microsomal (but not the nuclear) fractions of rat endometrial tissues. Uric acid also accumulated in the endometrium of copper-treated rats, but not in those fitted with a nylon device or sham operated. It is suggested that the contraceptive effect of copper may be related to these events.

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R. DENAMUR, J. MARTINET and R. V. SHORT

Summary.

Twice-daily intramuscular injections of 0·5 mg oestradiol benzoate, starting on Day 3 of the cycle, were able to prolong the life of the corpora lutea in sheep, as judged by their weight, their DNA and RNA content, and the progesterone concentration in ovarian vein blood. This luteotrophic effect persisted even when the pituitary stalks of the animals were sectioned, but it was abolished when the animals were hypophysectomized.

Four possible sites of oestrogen action were considered; the hypothalamus, the pituitary, the corpus luteum and the uterus. It was concluded that oestrogen is luteotrophic principally because of its action on the uterus, where it seems to interfere with the normal luteolytic mechanism.

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J. M. R. RAWSON and W. R. DUKELOW

Summary.

Laparoscopic observation of the ovaries of seventeen adult regularly cycling Macaca fascicularis was made during their menstrual cycles at the optimal time for detecting follicular development. Preovulatory morphology, follicular rupture and immediate postovulatory morphology were noted and photographed. Data are presented correlating the duration of the follicular phase and the luteal phase with that of the total cycle.

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R. R. Bodkhe and M. J. K. Harper

Summary. Metabolism of PGE-2 and PGF-2α by cytosolic fractions (100 000 g supernatant) of rabbit uterus, oviduct and lung was measured in vitro. Metabolism of PGE-2 was greater than that of PGF-2α for oviduct and uterus. After an ovulating injection of hCG metabolism of both PGE-2 and PGF-2α by lung and uterus declined linearly up to 72 h (during the time of ovum transport). The amount of PG metabolism by the oviduct did not change significantly during this period, but the percentage changes of PGE-2 and PGF-2α metabolism from oestrous values did differ, and perhaps indicated a change in the ratio of intracellular PGs. No change of metabolism of either PG by lung, uterus or oviduct occurred at 24 or 72 h after an injection of 250 μg oestradiol cyclopentylpropionate given concomitantly with the hCG (a treatment regimen which causes 'tube-locking' of ova). However, progesterone treatment, in a regimen known to cause accelerated transport of ova through the oviduct, caused significantly enhanced metabolism of both PGE-2 and PGF-2α by uterus and oviduct, but not lung, 30 and 48 h later except for PGE-2 by uterus at 30 h. These results suggest that changes in metabolism of PGE-2 and PGF-2α by the oviduct may be involved in the mechanisms controlling ovum transport.

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I. A. R. More and R. G. Masterton

Summary.

The incidence of ciliated cells in the human endometrium was determined. Conditions associated with an excess of oestrogenic activity were characterized by an increased incidence of ciliated cells, whilst oestrogen deficiency was associated with decreased numbers. When endometrium was cultured, addition of oestradiol-17β caused an increase in the ciliated cell population.

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R. B. LAND and W. R. CARR

Summary.

The mean testis diameter of 20- to 25-week-old Blackface, Finn and Merino rams was ranked in the same order as the ovulation rates of females of their breeds. The removal of one testis at 12 or 16 weeks of age resulted in hypertrophy of the remaining testis. The relative increase in testis growth following hemicastration was greatest in the Merino rams (72%), least in the Finns (42%) and intermediate in the Blackfaces (57%), so that it was inversely related to their breed ovulation rates. This hypertrophy was associated with increases in the concentration of plasma LH in all breed types.

The results indicate that differences in testis growth rate are associated with differences in gonadotrophic stimulation rather than intrinsic growth potential, and it is postulated that these may arise from breed differences in sensitivity to negative feed-back from the testes.

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R. H. F. Hunter and R. Nichol

Summary. Fine thermistor probes positioned in each end of the same oviduct and connected to the same scale were used to measure temperature gradients in the lumen before and after spontaneous ovulation in normally-cyclic gilts. Readings were taken after full surgical closure of a mid-ventral incision and a subsequent period of stabilization, but whilst animals remained under general anaesthesia.

A small but consistent difference in temperature was recorded between the proximal ampulla and distal isthmus of the same oviduct in each of 20 preovulatory gilts. In 10 of these animals that had not mated, the isthmus was a mean of 0·43°C cooler than the ampulla (range 0·2–0·7°C whereas in 10 mated animals the isthmus was 0·69°C cooler (range 0·2–1·6°C 3 animals in the latter group had within-oviduct differences of ≥ 1°C. By contrast, in 12 animals that had recently ovulated, the isthmus was a mean of only 0·1°C cooler than the ampulla; there was no measurable temperature gradient in 3 of the animals, whilst the isthmus was 0·1°C warmer in 2 animals. The preovulatory temperature differences are thought primarily to reflect the extent and activity of the vascular and lymphatic beds in the oviduct tissues and, together with specific chemical microenvironments, may facilitate the relatively prolonged period of sperm storage in the distal portion of the isthmus.

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W. R. Allen and R. L. Pashen

Summary. The blastomeres of 19 2- to 8-cell embryos recovered surgically 1–3 days after ovulation from 23 Pony mares were mechanically separated and inserted, in various combinations, into evacuated pig zonae pellucidae to make 27 'half' and 17 'quarter' micromanipulated embryos. These were embedded in agar and cultured in vivo in the ligated oviducts of ewes for 3·5–5 days to allow development to the late morula/early blastocyst stage. Subsequent surgical or non-surgical transfer of 13 'half' and 17 'quarter' embryos to mares resulted in 10 established pregnancies, including 2 monozygotic pairs. Surgical transfer to mares that had not been recently used as donors of embryos was more successful (10/20) than surgical or non-surgical transfer to recently operated mares (0/10).

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S. K. BATTA and R. R. CHAUDHURY

Summary.

The intraluminal fluid from the rat uterus with an intrauterine silk thread suture exerts an anti-implantation effect when administered intraluminally into the uterus of a recipient rat on Day 2 and Day 4 but not on Day 6 of pregnancy. It is suggested that the intra-uterine device exerts its antifertility effect by release of a pharmacologically active agent.