The growth of collagen in the foetus, placenta and foetal membranes of the rat

Abstract

. We have now made quantitative observations on the collagen content of the placenta, membranes and foetus of the rat during pregnancy. In all cases collagen content increased more rapidly than wet or dry weight. In the course of this work we also studied the quantity of amniotic fluid present at different times of pregnancy. METHODSAlbino rats ofthe local strain were used. Pregnancy was timed to ± 1 day by the method previously used (Harkness & Harkness, 1954b). Collagen was estimated by the method of Neuman & Logan (1950) with minor modifications (Harkness & Harkness, 1954a). Dryweightoftissueswas measured after drying over phosphorus pentoxide in vacuo. Total nitrogen was measured by the Kjeldahl procedure; digestion was done by the method of Chibnall, Rees & Williams (1943) and the ammonia was estimated after distillation into boric acid containing bromeresol green-methyl red indicator (Conway, 1947). The placenta and foetuses were homogenized in a small blendor of the Waring type. This did not break up all the individual bones of the older foetuses but we found that this did not appreciably affect the estimation. For both foetuses and placentas, judged by the hydroxyproline content of the residuum, the amount of collagen left after the usual aliquot was removed for analysis after autoclaving (Harkness & Harkness, 1954a) corresponded to the amount expected from the size of the aliquot, i.e. if any collagen in the bones remained undissolved after autoclaving the amount was too small to affect the results appreciably. Tyrosine estimations were made by the method of Medes (1932) on a number of samples and the quantity was small enough to be neglected. The hydroxyproline values have been accepted without correction for tyrosine.The animals were killed by a blow on the head and breaking the neck. The whole uterus was removed and weighed. The horns were opened and the foetuses removed with their placentas and membranes enclosing the amniotic fluid intact. The foetuses were then separated from the placentas, umbilical cords and membranes. These structures, together with the foetuses and empty uterus, were weighed and the weight of amniotic fluid was obtained by difference from the original 15 PHYSIO. CXXVIII

Transcriptome landscape of the human placenta

“…When the analysis was performed on all of the tissues combined, we observed the overrepresentation of ECM-related gene sets such as integrin signaling pathway, ECM-receptor interaction, focal adhesion, and integrin cell surface interactions. These results provide evidence for the role of ECM in placental development and placental cell proliferation as demonstrated in earlier studies [ 73 , 74 ].…”

Changes in the physical properties of the uterine cervix of the rat during pregnancy

“…From then on there is a continuous increase in the circumference of the cervix. There is nothing in the time course to suggest a relation with the weakening of the foetal membranes (Harkness & Harkness, 1955) which takes place rapidly at about the 19th day. It is of interest, however, that when allowance is made for a small difference in duration of pregnancy the time course of the change closely resembles that found by Hall & Newton (1946) for the separation of the ends of the symphysis pubis of the mouse (Fig.…”

Identification of genes contributing to preterm birth

“…The placenta, during its development, is exposed to different oxygen environments and tight regulation of oxygen homeostasis is necessary for proper placental development and function, which requires active involvement of the HIF1-alpha TF network (Fryer and Simon 2006). These (Harkness and Harkness 1955;Poschl et al 2004).…”