Whole bovine nuchal ligaments, or portions thereof (in the case of commercially valuable animals), were obtained from 45 animals (28 fetal and 17 postnatal) ranging in age from 110 days of gestation to 10 yr. Insoluble elastin was quantitatively prepared from the fresh ligaments by extraction with hot alkali and by a combination of multiple extractions with alkaline buffer and then repeated autoclaving. When adult samples were examined, the yields of insoluble residue by these two methods were very similar, but with young fetal samples the second method gave significantly higher values, because of incomplete purification of the elastin residue. The changes in the concentration of collagen, alkali-insoluble elastin, and DNA have been examined. DNA concentration, and, thus, cell population density, fell progressively during the fetal period of development, to reach a steady value soon after birth. Collagen appeared in appreciable quantities before elastin, but its concentration was rapidly halved at about the time of birth. Insoluble elastin concentration was low until the end of the 7th fetal month, at which time it began to rise rapidly. The rate of increase in elastin concentration remained high throughout the next 10-12 wk, by which time the adult value had been reached. Quantitative studies, on the basis of the whole ligament, showed that the total cell content rises to a maximum at birth, but falls soon after to a level about half that at birth. Total collagen production and elastin deposition continue at a steady, maximal rate over the interval from 235 days of gestation to the end of the 1st postnatal month. It is concluded that the immediate postnatal period would be the most favorable phase in which to attempt the isolation of the soluble precursor elastin.

Amino Acids↗

PubMed1967

Histological changes during the development of the bovine nuchal ligament.

The histological changes occurring during the development of the bovine nuchal ligament have been observed in sections of formalin-fixed material from 21 animals ranging in age from 110 days of gestation to 10 yr. The elastic fibers which constitute the bulk of the adult ligament were initially few in number. During fetal development, the fibers showed a rapid increase both in number and in their stainability with the usual elastic stains. The average diameter of these elastic fibers increased only slowly until the last uterine month, at which time it began to increase very rapidly. This rapid rate of increase continued through the first 6 postnatal months, after which the rate of increase slowed markedly. However, the fiber diameter continued to rise steadily throughout the period of the study. During the fetal stage of development, the fibroblastic cells of the ligament exhibited unusual nuclear appearances which distinguish them from other fibroblasts. These consisted of marked clumping of the chromatin and an associated nuclear vacuolation or vesiculation. While these changes seem likely to be artefacts of fixation, their temporal correlation with elastin deposition and their demonstration in other tissue cells engaged in elastin production suggest that the factors responsible for these appearances may be related to elastin synthesis.

Animals↗

PubMed1966

The incorporation of lysine into growing elastin.

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Animals↗

PubMed1966

Antigenic properties of soluble elastins and their use in detecting soluble elastin in ligament extracts.

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Animals↗

PubMed1965

The swelling of bovine ligamentum nuchae as a function of pH.

1. The swelling and solubilization of foetal and adult bovine ligament over a range of pH values has been investigated. 2. Maximum swelling occurs at pH2.7 and pH8.5 for both types of ligament. Abover pH13 complete solubilization occurs. 3. Considerably greater swelling and solubilization occurs with foetal ligament below pH12. 4. The presence of 2m-sodium chloride markedly suppresses both swelling and solubilization. Above 1n-sodium hydroxide actual dehydration occurs and little or no protein is extracted. 5. It is suggested that the intermolecular cross-links in a considerable proportion of foetal elastin are weak and that extraction with aqueous salt solution at pH8.5 would provide optimum conditions for extracting soluble proteins, including soluble elastin if this is present.

Animals↗