TECHNIQUES FOR THE LONG‐TERM COLLECTION OF LYMPH FROM THE UNANAESTHETIZED FOETAL LAMB <i>IN UTERO</i>

Smeaton, TC; Cole, GJ; Simpson‐Morgan, M. W.; Morris, Bede

doi:10.1038/icb.1969.150

Cited by 27 publications

(14 citation statements)

References 3 publications

(6 reference statements)

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“…Procedures for intrauterine surgery on fetal lambs have been described by several groups of investigators [Meschia, Cotter, Breathnach and Barron, 1965;Smeaton, Cole, Simpson-Morgan and Morris, 1969;Comline and Silver, 1970a;Faber and Green, 1972]. The uterus was left in situ and no more of the fetus was exposed than was necessary for surgical access.…”

Section: Animalsmentioning

confidence: 99%

Arterial Blood Pressure in the Unanaesthetized Fetal Lamb After Changes in Fetal Blood Volume and Haematocrit

1974

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Fourteen sheep fetuses in the third trimester of gestation were surgically prepared with intravascular catheters and five were nephrectomized. All experiments were done on unanaesthetized fetuses in utero, 3 to 9 days after surgery. Mean arterial blood pressure was recorded while fetal blood volume was changed by injection or withdrawal of blood, or infusion of Ringer's or dextran solutions. Fetal arterial blood gases and pH changed little during the experiments and were shown not to have affected the results. Arterial blood pressure was strongly influenced by changes in fetal blood volume and was also found to depend on haematocrit. There were no detectable differences between the responses of normal and nephrectomized fetuses or between normal fetuses and fetuses treated with hexamethonium. In all preparations central venous pressure depended on blood volume. Heart rate did not depend on blood volume in normal fetuses, but an increase in heart rate with an increase in blood volume was seen after hexamethonium. The open loop gain of baroceptor control of arterial blood pressure could not be proved to differ significantly from zero. Venoconstrictor responses and heart rate responses of reflex origin did not occur when arterial blood pressure was changed. The absence of detectable baroceptor control appears to explain the great sensitivity of arterial blood pressure to blood volume in the unanaesthetized fetal lamb. Previously we found that fetal placental blood flow is almost proportional to fetal blood volume [Faber, Gault, Green and Thornburg, 1973]. Since placental resistance to flow is not known to be under fetal control, changes in placental blood flow were thought to be secondary to changes in arterial blood pressure, an explanation which would require that arterial blood pressure itself is also proportional to blood volume. Studies that demonstrate some control of arterial blood pressure by the baroceptors of the fetus [Brinkman, Ladner, Weston and Assali, 1969] and the neonate [Downing, 1960; Downing, Gardner and Rocamora, 1969] seem to argue against this supposition and we therefore investigated the relationship between arterial blood pressure and blood volume in unanaesthetized fetal lambs under near normal conditions. The contributions of the baroceptors, and of renal mechanisms, to the regulation of arterial blood pressure were assessed by experiments on fetuses with blocked ganglionic transmission or previous bilateral nephrectomy. Recordings of the pH, P02, and PCO2 of fetal arterial blood were made to monitor the condition of the preparations and to eliminate the possibility that the chemo-ceptors affected arterial blood pressure in these experiments. METHODS Animals Pregnant western mixed breed and Dorset ewes were starved for 24 hr prior to surgery and operated on under nitrous oxide-halothane anaesthesia, after induction 241

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Section: Animalsmentioning

confidence: 99%

Arterial Blood Pressure in the Unanaesthetized Fetal Lamb After Changes in Fetal Blood Volume and Haematocrit

1974

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“…(Pentothal, 50 mg/mL; Boehringer Ingelheim) and maintained on 1.5% halothane (Fluothane; ICI, Australia) and oxygen in a closed circuit system. The uterus was externalized and the fetus exposed according to the procedure of Smeaton et al [45]. A cannula was inserted into the jugular vein for administering BrdU and collecting blood samples.…”

Section: Animals and Surgerymentioning

confidence: 99%

Cell death and thymic export during fetal life

et al. 2006

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In the fetus the peripheral T cell pool expands as the fetus grows, but the mechanisms that regulate T cell homeostasis during fetal life are unknown. Here, we show that the peripheral T cell pool in the sheep fetus is established by the export from the fetal thymus of twice as many CD8 + as CD4 + thymic emigrants every day. Clonal deletion of CD4 + thymocytes in the fetal thymus appeared to be more stringent than was the case for CD8+ thymocytes because only 1 in 35 single-positive CD4 (SPCD4) thymocytes was exported from the thymus whereas the majority (2/3) of the single-positive CD8 (SPCD8) thymocytes were exported from the fetal thymus each day. Furthermore, within the thymus, the number of apoptotic SPCD4 thymocytes was 40 times greater than the number of apoptotic SPCD8 thymocytes. A tissue-specific migration of CD8 + emigrants localizing in the spleen was also established in the fetus in contrast to CD4 + emigrants, which migrated randomly to spleen and LN.

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“…The general aspects of surgery on fetal sheep were similar to previous descriptions. 15,16 At 63 days of gestation the fetus was exposed by Caesarean section under thiopentone and halothane anaesthesia. The fetus received a single intraperitoneal injection of a monoclonal antibody directed against sheep IgM (McM9).…”

Section: Experimental Protocolmentioning

confidence: 99%

Fetal lambs are depleted of IgM⁺ cells following a single injection of an anti‐IgM antibody early in gestation

et al. 1996

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SUMMARYB-cell depleted fetal sheep were created following a single injection of an anti-IgM monoclonal antibody early in gestation. Six sheep fetuses were given a single intraperitoneal injection of a monoclonal antibody directed against IgM at 63 days of gestation (gestation in sheep 150 days). The fetuses were killed at 138-142 days of gestation and lymphoid tissues were collected for subsequent light microscopy and immunohistochemical examination. The ileal and jejunal Peyer's patch (PP) follicles in four of the six injected fetuses were markedly reduced in size. Cells in the rudimentary follicles of the ileal PP of these animals showed no reactivity for IgM and most were negative for CD45. The dome regions contained many T cells, which were predominantly CD8 cells and included

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TECHNIQUES FOR THE LONG‐TERM COLLECTION OF LYMPH FROM THE UNANAESTHETIZED FOETAL LAMB IN UTERO

Cited by 27 publications

References 3 publications

Arterial Blood Pressure in the Unanaesthetized Fetal Lamb After Changes in Fetal Blood Volume and Haematocrit

Arterial Blood Pressure in the Unanaesthetized Fetal Lamb After Changes in Fetal Blood Volume and Haematocrit

Cell death and thymic export during fetal life

Fetal lambs are depleted of IgM⁺ cells following a single injection of an anti‐IgM antibody early in gestation

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TECHNIQUES FOR THE LONG‐TERM COLLECTION OF LYMPH FROM THE UNANAESTHETIZED FOETAL LAMB IN UTERO

Cited by 27 publications

References 3 publications

Arterial Blood Pressure in the Unanaesthetized Fetal Lamb After Changes in Fetal Blood Volume and Haematocrit

Arterial Blood Pressure in the Unanaesthetized Fetal Lamb After Changes in Fetal Blood Volume and Haematocrit

Cell death and thymic export during fetal life

Fetal lambs are depleted of IgM+ cells following a single injection of an anti‐IgM antibody early in gestation

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Fetal lambs are depleted of IgM⁺ cells following a single injection of an anti‐IgM antibody early in gestation