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Biomedical subjects

R M Moor

Publications and source records attributed to R M Moor.

At least 145 records · Page 8Linked to original sources
PubMed1976

Oxygen uptake, glucose utilization, lactate release and adenine nucleotide content of sheep ovarian follicles in culture: effect of human chorionic gonadotrophin.

A study has been made of the oxygen uptake, glucose utilization, lactate release and cellular content of adenine nucleotides of isolated sheep ovarian follicles (4-6 min in diameter) maintained in organ culture, and of the effects on these parameters of the addition of human chorionic gonadotrophin (hCG). The mean oxygen consumption of the entire follicles when freshly isolated and of the theca and membrana components was 0-56, 1-08 and 0-05 mumol per milligram wet weight of tissue per hour respectively. About 8 mumol of glucose was taken up and 16 mumol of lactate released per milligram wet weight of follicular tissue per hour during the first 24-h period of culture. This rate reduced by about 30% for each subsequent day of culture, but was significantly increased by the addition of hCG. The mean ATP content of theca and granulosa tissues was 4-6 and 2-8 nmol/mg wet weight of tissue respectively. There was no discernable change in tissue adenine nucleotide content or energy charge ratio during the 3-day culture period, and prolonged exposure to hCG was without effect. Untreated follicles produced both oestrogen and androgens throughout the culture period. The addition of hCG resulted in a transitory stimulation in oestrogen secretion, inhibition of androgen secretion, and a marked and sustained rise in progestin secretion. It is proposed that the increase in glycolytic activity following exposure to hCG may relate to the activation of the granulosa cells coincident with a transference of steroid synthetic capacity from theca interna to membrana granulosa.

Adenine Nucleotides↗
PubMed1976

Permeability of ovarian follicles to electron-dense macromolecules.

Ferritin (m.w. 500 000) perfused into the ovarian arteries of sheep permeated the theca interna and was also found in the membrana granulosa of both non-atretic and atretic Graafian follicles. Colloidal gold (m. w. 1 000 000) similarly perfused, was found in the theca interna but not in the granulosa. The results are discussed in terms of the blood-follicle barrier.

Animals↗
PubMed1976

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. Blood flow to the vagina and cervix increased by over 10-fold from day 14 to 15 but vaginal and cervical weights remained unchanged. Thirty minutes after the administration of 1200 IU PMSG, blood flow increased in the vagina and cervix on day 14, the myometrium on day 15 and the vagina, cervix and oviducts on day 16. However, these results must be viewed with caution since there were substantial, though not significant changes in the controls. The results favour the hypothesis that, near the end of the oestrous cycle, oestrogen has a dominant role in the control of blood flow to the reproductive tract of sheep.

Animals↗
PubMed1976

Deep freezing of sheep embryos.

Sheep embryos, collected 1-8 days after oestrus, were placed in Dulbecco's phosphate-buffered saline medium (PBS). After treatment, the viability of the embryos was tested by temporary transfer to ligated rabbit oviducts. In Exp. 1, Days 5-8 embryos survived for at least 15 min at 0 degrees C in the presence of 1-5 M-DMSO. In Exp. 2, 12/14 Days 5-8 embryos survived after being frozen in 1-5 M-DMSO at 0-3 degrees C/min to temperatures ranging between-15 degrees and -60 degrees C and then thawed at 12 degrees C/min. In Exp. 3, Days 5-8 embryos were frozen in 1-5 M-DMSO at 0-3 degrees C/min to below-65 degrees C before being transferred to liquid nitrogen (-196 degrees C), and stored for 12 hr to 1 month. The embryos were thawed at 3 degrees C/min, 12 degrees C/MIN or 360 degrees C/min and, after transfer to rabbit oviducts, 0/4, 10/36 and 1/4, respectively, developed normally. The 11 embryos which were considered normal when recovered from the rabbit oviducts plus 1 slightly retarded embryo were transferred to 7 recipient ewes. Four ewes subsequently lambed, producing 5 lambs. In addition, 8 embryos were transferred to 4 ewes directly after thawing. Three of these ewes subsequently lambed, producing 3 lambs.

Animals↗
PubMed1976

Artificial insemination with spermatozoa in formaldehyde.

The ability of formaldehyde to preserve the integrity of the membranes of spermatozoa, as indicated by eosin staining (Dott & Foster, 1975), prompted an investigation to discover what other properties of spermatozoa were preserved by low concentrations of formaldehyde in vitro. In a series of experiments on bull, ram and boar spermatozoa it has been shown that spermatozoa rendered immotile by formaldehyde recovered their motility when the formaldehyde was removed by washing up to 12 hr afterwards (H.M. Dott & G.C. Foster, unpublished). To find out if fertility was preserved ewes and sows were inseminated with spermatozoa rendered immotile with formaldehyde.

Animals↗
PubMed1976

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.min-1 .100 g-1 tissue) was 1122, 708 and 116 to the CL; 157, 258 and 140 to the stroma; and 627, 742 and 1096 to the follicles, respectively. Blood flow to grossly atretic follicles did not differ significantly from that to non-atretic follicles of an equivalent size. Change in blood flow do not appear to initiate or control the activation, steriodogenic function or atresia of follicles.

Anesthesia, General↗
PubMed1976

Cyclic AMP in sheep ovarian follicles: site of production and response to gonadotrophins.

This study was undertaken (i) to establish a relationship between cyclic AMP (cAMP) production and the degree of LH and FSH stimulation; (ii) to determine the effects of various gonadotrophins on follicular formation of cAMP; and (iii) to identify the precise intrafollicular site of cAMP formation. The formation of cAMP increased rapidly in follicles exposed to LH. Maximum concentrations were reached after 90 min and were maintained for 180 min. Extracellular release of cAMP increased steadily throughout the 180-min experimental period. Tissue levels of cAMP increased proportionally and significantly when LH concentrations in the medium were increased from 0 to 200 mi.u. ml-1. Tissue levels of cAMP were significantly increased by HCG, prostaglandin E-2 and noradrenaline, but not by prolactin, prostaglandin F-2alpha, serotonin or melatonin. Cyclic AMP formation occurred predominantly in the thecal compartment; the membrana granulosa contributed less than 3% of the total amount of cAMP formed after gonadotrophic stimulation. A significant amount of cAMP from the thecal cells was released into the extracellular compartment and appeared to pass into the granulosa cells.

Animals↗
PubMed1976

Pregnant mare serum gonadotrophin: ratio of follicle-stimulating hormone and luteinizing hormone activities measured by radioreceptor assay.

Specific radioreceptor assays for FSH and LH, which employ tissue receptors from rat testis and highly purified human FSH (LER 1575-C) and LH (Hartree IRC-2, 24/6/69) as standards, have been developed to determine the FSH-like and LH-like activities in pregnant mare serum gonadotropin (PMSG). Measurements of FSH and LH concentrations in the serum of six pregnant Pony mares showed that the ratio of these two activities did not vary significantly between mares and remained constant between days 40 and 80 of gestation with a value of 1-45 +/- 0-04 (S.E.M.). The FSH:LH ratio of PMSG produced by cultured equine trophoblast cells was found to be 0-72 +/- 0-03 (S.E.M.) and that of partially purified serum extracts of PMSG 1-08 (range 0-87-1-30).

Animals↗
PubMed1975

Distribution of delta-5 -3beta-hydroxysteroid dehydrogenase activity in the Graafian follicle of the sheep.

The localization of delta-5 -3beta-hydroxysteroid dehydrogenase (3 beta-HSD) has been examined in ovarian follicles in vivo and in vitro, and related to oestrogen and progesterone production. In vivo, during the oestrous cycle, enzyme activity was restricted to the theca interna of the one or two most advanced follicles in each animal, but was present only between Day 2 and 5 and between Day 13 and ovulation. High levels of oestrogen were found in the ovarian venous blood only when follicles containing 3 beta-HSD were present. When sheep were injected with PMSG, the theca interna in a number ofsmall follicles acquired 3 beta-HSD activity and began to secrete oestrogen within 12 hr of the injection. The enzyme was not detected in the membrana granulosa of any follicles before ovulation but within a few hours of ovulation, 3 beta-HSD activity was present in the granulosa lutein cells. In vitro, large activated follicles exhibited 3 beta-HSD activity in the theca interna and secreted high levels of oestrogen into the culture medium. When LH was added to the medium oestrogen secretion was inhibited; within 48 hr, the follicles were secreting high levels of progesterone, and 3 beta-HSD activity was present in both the membrana granulosa and the theca interna. Dibutyryl cyclic adenosine monophosphate mimicked the effect of LH in suppressing oestrogen secretiion, but did not induce production of progesterone; the distribution of 3 beta-HSD activity infollicles treated with this nucleotide was the same as in those cultured in control medium.

Animals↗
PubMed1975

Pregnant mare serum gonadotrophin: rate of clearance from the circulation of sheep.

The process involved in the disappearance of PMSG from the blood of sheep, following a single intravenous injection, has been separated into two exponential components. Values (mean plus or minus S.E.) calculated from experiments on five animals were: metabolic clearance rate (37.8 plus or minus 1.6 ml hr-minus 1); rate constant of disposal (0.0315 plus or minus 0.0016 hr-minus 1); half-time of disposal (21.2 plus or minus 1.1 hr). The stage of the oestrous cycle, ovariectomy and the dose of PMSG used had no apparent effect on these values.

Animals↗
PubMed1975

Experiments on egg transfer in the cow and ewe: dependence of conception rate on the transfer procedure and stage of the oestrous cycle.

The effects on embryo survival of procedures used in transferring eggs non-surgically were investigated in three experiments in ewes and heifers. In Exp. 1, two techniques for introducing eggs into the uterus through the cervix in heifers were compared; namely (i) deposition of the eggs high into the uterine horn or (ii) into the body of the uterus. Both methods were followed by inflation of the uterus with carbon dioxide. Out of a total of 34 heifers, only one became pregnant by the use of Method (i). Non-surgical egg tansfers early (Days 3 to 5) or later (Days 6 to 9) in the oestrous cycles of heifers were carried out in Exp. 2. Three transfer procedures were compared: (i) pipette transfer of an egg into the body of the uterus through the cervix (control), (ii) the control procedure performed under Fluothane anaesthesia, or (iii) followed by inflation of the uterus with carbon dioxide. Wide transfers carried out early in the cycle, pregnancies resulted in 1/10, 0/10 and 1/10 of the heifers in the control, carbon dioxide and Fluothane groups, respectively. With late transfers, 7/20, 1/10 and 8/20 heifers became pregnant in the respective treatment groups. This trend for pregnancy rate to be improved when late transfers were done in the control and Fluothane groups was significant only at the 10% level of probability when both groups were pooled. It was tentatively concluded, however, that non-surgical transfers of fertilized eggs to heifers may be best done during mid-cycle, after Day 6. Fluothane anaesthesia did not improve conception rate. Inflation of the uterus with carbon dioxide appeared to be deleterious when used at the mid-cycle stage in heifers. In Exp. 3, it was found that inflation of the ewe's uterus with carbon dioxide or nitrogen following the surgical thansfer of an egg did not affect the incidence of pregnancy. The introduction of 50 mul liquid Fluothane into the lumen of the uterus was embryotoxic.

Animals↗
PubMed1975

Functional and structural relationships in the Graafian follicle population of the sheep ovary.

The Graafian follicle population in sheep can be divided into two groups on the basis of the capacity that individual follicle have for secreting oestrogen when isolated from the remainder of the ovary (Moor, 1973). The most developed one or two non-atretic follicle from each animal generally produce large amounts of oestrogen in culture and can thus be classified as steroidogenically 'activated'. The other follicles usually produce very little oestrogen in culture and are accordingly classified as 'non-activated'. In this paper the above classification will be used and the two groups of follicles will be considered separately. In the first section of the paper the response of the non-activated follicles to gonadotrophic stimuli will be described and related to growth and atresia within this population. The steroidogenic potential of the activated follicles at different stages of the cycle will be discussed in the second part of the paper. In the third part, an attempt will be made to relate the ultrastructure of the activated follicles to the functional activity of their component tissues, namely the theca interna and membrana granulosa.

Androstenedione↗
PubMed1975

The sheep ovary: regulation of steroidogenic, haemodynamic and structural changes in the largest follicle and adjacent tissue before ovulation.

Important changes occur in the follicle that is destined to ovulate and also in the surrounding ovarian tissue of sheep during the 72 hr preceding ovulation. It is our purpose to describe the morphological and functional changes that take place in large follicles during the preovulatory period and to relate these to the local ovarian environment and general endocrine status prevailing at this time. A consideration of changes in the structure, blood supply and function of the ovaries in vivo, is followed by a discussion of the functional capacity of the individual ovarian components when isolated and studied in vitro. Against this background, the nature and sequence of events that occur in the preovulatory follicle and the mechanisms which regulate them will be discussed.

Adenylyl Cyclases↗
PubMed1975

Origin and histogenesis of equine endometrial cups.

Biochemical and morphological studies were carried out to determine the origin and histogenesis of endometrial cups in mares. A wide range of fetal and maternal tissues were cultured in vitro and their ability to secrete gonadotrophin (PMSG) was monitored. High levels of PMSG were produced in culture only by cells from the restricted area of the equine trophoblast known as the chorionic girdle which is an annular band of highly specialized cells at the junction of the allantois and the regressing yolk sac. The morphological appearance of girdle cells after cultivation in vitro and after allogeneic grafting to the uterus or testis was identical to that of endometrial cup cells. Firm attachment between the cells of the chorionic girdle and the adjacent endometrium occurs on Day 36. Girdle cells then rapidly invade and phagocytose the endometrial epithelium, and migrate into the endometrial glands and the uterine stroma where they differentiate into large, sessile endometrial cup cells.

Animals↗