The Diameter of Foetal Sheep Erythrocytes

Mj, Karvonen

doi:10.1159/000140888

Cited by 7 publications

(4 citation statements)

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“…In the sheep, erythrocytes have been shown to decrease in size with advancing foetal age (Karvonen 1954). The increase in packed cell volume obtained in this experiment and illustrated in Figure 2 is most probably due therefore to a relative increase in the number of circulating cells.…”

Section: Discussionsupporting

confidence: 53%

“…Alterations in the degree of anoxaemia and the theory of a double cell population are the two hypotheses which have been evoked to explain the blood changes which occur at birth. Karvonen (1954) has demonstrated two cell sizes in the blood of foetal sheep using Price-Jones curves, but he could not accept the interpretation of a two-cell population because the transition did not reflect the change from foetal to adult haemoglobin, nor did the development of medullary haematopoiesis fit the same time scale. He suggests that the more likely explanation for the change is the difference in oxygenation.…”

Section: • •mentioning

confidence: 99%

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Electrolyte and Haematocrit Changes in The Blood of Sheep From Foetal to Postnatal Life

Evans¹,

Blunt²

1961

Aust. Jnl. Of Bio. Sci.

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Section: Discussionsupporting

confidence: 53%

Section: • •mentioning

confidence: 99%

Electrolyte and Haematocrit Changes in The Blood of Sheep From Foetal to Postnatal Life

Evans¹,

Blunt²

1961

Aust. Jnl. Of Bio. Sci.

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“…UL cell size was determined by measuring the perimeter of 60-80 of the largest UL adipocytes using the stereology software NDP.view2 (Hamamatsu Photonics). Tissue shrinkage was estimated by measurement of the diameter of red blood cells in each section and the perimeter measurements of each fetus were adjusted by 40-50% (23). There was no significant difference in tissue shrinkage between the samples from the TX and sham groups.…”

Section: Adipose Tissue Histologymentioning

confidence: 99%

Thyroid Deficiency Before Birth Alters the Adipose Transcriptome to Promote Overgrowth of White Adipose Tissue and Impair Thermogenic Capacity

Harris

Blasio

Zhao

et al. 2020

Thyroid

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Background: Development of adipose tissue before birth is essential for energy storage and thermoregulation in the neonate and for cardiometabolic health in later life. Thyroid hormones are important regulators of growth and maturation in fetal tissues. Offspring hypothyroid in utero are poorly adapted to regulate body temperature at birth and are at risk of becoming obese and insulin resistant in childhood. The mechanisms by which thyroid hormones regulate the growth and development of adipose tissue in the fetus, however, are unclear. Methods: This study examined the structure, transcriptome, and protein expression of perirenal adipose tissue (PAT) in a fetal sheep model of thyroid hormone deficiency during late gestation. Proportions of unilocular (UL) (white) and multilocular (ML) (brown) adipocytes, and UL adipocyte size, were assessed by histological and stereological techniques. Changes to the adipose transcriptome were investigated by RNA sequencing and bioinformatic analysis, and proteins of interest were quantified by Western blotting. Results: Hypothyroidism in utero resulted in elevated plasma insulin and leptin concentrations and overgrowth of PAT in the fetus, specifically due to hyperplasia and hypertrophy of UL adipocytes with no change in ML adipocyte mass. RNA sequencing and genomic analyses showed that thyroid deficiency affected 34% of the genes identified in fetal adipose tissue. Enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) pathways were associated with adipogenic, metabolic, and thermoregulatory processes, insulin resistance, and a range of endocrine and adipocytokine signaling pathways. Adipose protein levels of signaling molecules, including phosphorylated S6-kinase (pS6K), glucose transporter isoform 4 (GLUT4), and peroxisome proliferator-activated receptor c (PPARc), were increased by fetal hypothyroidism. Fetal thyroid deficiency decreased uncoupling protein 1 (UCP1) protein and mRNA content, and UCP1 thermogenic capacity without any change in ML adipocyte mass. Conclusions: Growth and development of adipose tissue before birth is sensitive to thyroid hormone status in utero. Changes to the adipose transcriptome and phenotype observed in the hypothyroid fetus may have consequences for neonatal survival and the risk of obesity and metabolic dysfunction in later life.

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“…Size differences between the RBC of the fetus vs that of the postnatal animal could account for some of the observed differences in binding, but the maximal ratio in surface areas between their RBC calculated from the data of Karvonen (1954), Ullrey et al (1965) and Upcott et al (1971) would only be 1.3 to 1.4, whereas the fetal cells bound two to three times as much insulin and had twice as many receptors. Thus, neither changes in the size (surface area) nor age of the RBC in the fetuses as compared with that of the postnatal animals and adults is likely to account for the observed differences in insulin binding.…”

Section: Discussionmentioning

confidence: 96%

Insulin Binding is a Specific Marker of Fetal Erythrocytes in Ruminants

Kappy

1983

Journal of Animal Science

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The ability of erythrocytes (RBC) from sheep and cattle of various gestational and postnatal ages to bind insulin specifically was studied. Insulin binding to RBC decreased as gestational and postnatal age advanced and was absent in blood obtained from adult animals. Maximal percentage 125I-insulin bound to RBC (3.6 X 10(9)/ml) was highest in the fetuses of sheep and cattle (7.3 +/- .6 and 7.8 +/- .9, respectively) compared to postnatal animals (2.3 +/- .2 and 2.2 +/- .3, respectively), or adults (no binding) of the same species. The decrease in binding began antenatally, and binding was projected to be insignificant by the end of the second postnatal month. Most of the observed decrease was due to a progressive decrease in the number of receptors on the cell surface. The time course of this phenomenon, as well as the total absence of insulin receptors on the RBC of adult ruminants, provides independent evidence that two distinct populations of RBC in ruminants exist. The gradual appearance of the adult RBC with no insulin binding results in a decrease in observed binding to RBC in a given blood specimen as fetuses and postnatal animals age.

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The Diameter of Foetal Sheep Erythrocytes

Cited by 7 publications

References 0 publications

Electrolyte and Haematocrit Changes in The Blood of Sheep From Foetal to Postnatal Life

Electrolyte and Haematocrit Changes in The Blood of Sheep From Foetal to Postnatal Life

Thyroid Deficiency Before Birth Alters the Adipose Transcriptome to Promote Overgrowth of White Adipose Tissue and Impair Thermogenic Capacity

Insulin Binding is a Specific Marker of Fetal Erythrocytes in Ruminants

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