Connective Tissue VI: Synthesis of Collagen by Rat Uterine Slices.

Abstract

of incorporatcd tritium lahellecl thymidine is distributed to thc daughter (.ell at mitosis( 1 ) one can exlmt that 1 y atlministering tritiutn labelled thymidine at 6 hour intervals, virtually all cells dividing during the period between booster injection of antigen and sacrifice would be exposed to, and incorporate labelled thymidine. The value of 92% stated as the labelling index of the plasma cell series here is probably conservative and may actually approach 100%. This low value might result )from the initiation and coinpletion of DNA synthesis in some cells between esposures to isotope or from technical limitations in the sensitization of the radiographic emulsion by the label in some cells. These factors, alone or in combination, would tend to lower the observed incidence af labelling. The results presented are in general agreement with those of other investigators employing similar technics (8,10,11) who have implicated a rapidly proliferating population of immature lymphablasts and plasmablasts as the chief source of plasma cells arising after antigenic stimulation. As a corollary. the large percentage of labelled antibody containing cells found in these experiments indicate that most plasma cells do not arise by direct, non-mitotic differentiation from small lymphocytes. The present studies could not offer quantitative data concerning the relative mitotic activity of the various stages leading to development of the mature plasma cell. However, by the use of colchicine and by short in vitro incubation of cells with thymidine it has been shown that functionally differentiated antibody producing cells can divide, indicating that mitotic activity within the family of antibody producing cells is not a n exclusive property of the immature or pre-CII rsor f orins.Suiiiiiinry. 14 technical approach for the study of the kinetics of antibody producing cells is possible by combination of autoradiography and the fluorescent antibody technic. Results show that: 1. Almost all antibody containing cells present by day 4 of a secondary response are newly formed cells arising ifrom mitotic division of a precursor sometime after antigenic stimulation; 2. Most plasma cells do not arise by direct, non mitotic differentiation from lymphocytes; and 3. Functionally differentiated antibody containing cells can divide.

Collagens of oral soft tissues

“…We interpret the observed age-dependent decrease of the specific activity of hydroxyproline in both soluble and insoluble collagen fractions ( Fig-2A) as an ,age-dependent decrease of the rate of synthesis of collagen by antemolar paiatai mucosa-Our results agree with the age-dependeot decrease of collagen synthesis observed in human skin (Uitto 1970), rat uterus (Kao et al 1962) and guitiea pig palatal mucosa (Claycomb et al-1967), Furthermore, our results were shown not to be due to isotopedilution, as a consequence of an increasing coiiagen mass, since a similar age-dependent profile was obtained (Fig-2C) when data was expressed as total activity per antemolar palatal mucosa. When data is expressed in this manner, the pre-existing pool of unlabeled collagen should not effect the overall profile.…”

Characteristics of uterine aging

“…In vitro experiments have shown, however, that the capacity of the uterus to synthesize collagen is a n inverse function of age (Kao et al, 1962;McGavack and Kao, 1963), while the nature and composition of collagen appear to be modified with time (Sobel, 1967). The amount of soluble collagen decreases as a percentage of the total with age, while the insoluble collagen increases (Kao and McGavack, 1959;McGavack and Kao, 1963), rendering the collagen more resistant to the action of bacterial collagenase (Woessner, 1963) and cathepsin (Schaub, 1965).…”

Aging in Connective Tissue: A Dynamic Process*

“…Thus far, our attempts to demonstrate the conversion of proline to hydroxyproline and of lysine to hydroxylysine in acellular systems have met with very little success. However, there are 2 in vitro tissue‐slice methods (18, 19, 22, 23) that can be adequately controlled for the study of various factors that may influence the formation and repair of connective tissue. One of us (KYK) has had considerable experience with connective tissue produced by sponges implanted under the skin of small laboratory animals.…”