Human foetal epithelial glycogen: a histochemical and electronmicroscopic study

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Composition of alveolar liquid in the foetal lamb

1. Experiments were performed on foetal lambs at gestations between 125 days and term. The foetus was exteriorized at Caesarean section with the umbilical cord and placental attachment maintained intact. Samples of liquid from the alveolar parts of the lung were withdrawn through a tracheal cannula and samples of lung lymph, plasma and amniotic liquid were also obtained. Measurements were made of total osmolality, concentrations of electrolytes and urea, pH and P(CO2). Titrations were carried out with N/10 HCl and N/10 NaOH. The water content of the liquids was estimated and concentrations expressed per kg H(2)O.2. In alveolar liquid [H(+)], [K(+)] and [Cl(-)] were higher and [Ca(2+)], [phosphates] and [HCO(3) (-)] were lower than in plasma or lymph. In amniotic liquid osmolality [Na(+)], [Cl(-)] and [Ca(2+)] were lower and [phosphates] higher than in plasma or lymph. Alveolar liquid/plasma ratios of [HCO(3) (-)], [Ca(2+)], [Cl(-)] and [K(+)] differed from ultra filtrate/plasma ratios of these ions.3. Titration curves demonstrated a very small amount of buffering in alveolar liquid at its in vivo pH of 6.27 mostly due to HCO(3) (-) at an average concentration of 2.8 mM/kg H(2)O.4. It is concluded that foetal alveolar liquid is not an ultrafiltrate of plasma nor a mixture of amniotic liquid and plasma ultrafiltrate, but a special material elaborated by the foetal lung.

Plasminogen activator activity in cultures from human tissues. An immunological and histochemical study

Human tissues and cells from pre- and postnatal life were cultivated and studied for plasminogen activator activity. Cultures were obtained from kidney, renal blood vessels, ureter, bladder, lung, and heart. Local activator activity of cells was demonstrated by histochemical techniques. Activator released by cells into the supernatant culture media was assayed by fibrin plate techniques and was investigated for immunological identity using specific antisera to an activator of human origin, urokinase (UK). Plasminogen activator was produced in primary cultures where cells retain specific functions and generally reflect the enzyme pattern of the tissues of origin. Cells from fetal and adult sources were found to yield activator antigenically identical to UK, as well as activator activity which differed from that of UK in immunoassays and which may represent tissue type activator. Such activity was released after injury or death of cells while UK was produced in cultures containing live, metabolizing cells. Primary cultures of kidney confirmed that this organ is a rich source of UK and demonstrated, in addition, that UK is produced from the early stages of gestation and in increasing amounts thereafter. However, primary cultures also demonstrated that the ability to produce UK is not limited to the kidney but is a function of cells which are distributed widely in body tissues. Thus, activator antigenically identical to UK accumulated progressively after many refeedings in culture supernates of fetal lung and ureter, as well as in supernates of renal blood vessels of adults. These findings indicate continuous formation of UK by the cultured cells and, furthermore, provide evidence of UK production in blood vessels. In cultures from other tissues, particularly those from fetal heart and adult lung and bladder, investigation of activator was hindered by inhibitory activity which accumulated in the supernates. Such activity was derived from cells in culture and was directed selectively against UK, indicating that inhibitor as well as UK are produced by cells of various organs of the body. Plasminogen activator also was produced by serially propagated cells, diploid and heteroploid. However, only diploid cell lines retained activator activity of the original tissues and continued to produce activator antigenically identical to UK. In contrast, heteroploid line appeared to have lost the ability to form UK by yielded activator activity that differed from that of UK in immunoassays. Serially propagated cells thus provide an additional tool for in vitro study of plasminogen activator and may facilitate investigation of the fibrinolytic system in man.

The distribution of coenzyme Q in the tissues of the gravid ewe and fetus

Data on coenzyme Q tissue concentrations were obtained from 26 ewes and their fetuses from 50 days postconception to term. Coenzyme Q concentrations were low in early embryonic life. A significant increase was observed in coenzyme Q concentration in the 4-month-old or older fetal heart and kidney. The mean concentration of coenzyme Q in fetal liver increased also with advance in gestation but with less consistency than in the other tissues.

Pancreatic insulin content of nonpregnant, pregnant and postpartum rats and the developing rat fetus

A study was made of the insulin content of pancreases of nonpregnant, pregnant and postpartum rats and of their developing fetuses. The insulin content of the extracts was measured by radioimmunoassay, using crystalline rat insulin as a standard. The mean concentration of insulin in the pancreas of nonpregnant animals was 43 ± 6 μg./gm. The insulin concentration did not change significantly during late pregnancy or on day 4 postpartum. However, the weight of the pancreas was significantly greater in the pregnant and the postpartum rats. Thus, the total insulin content of the pancreas was greater in the pregnant and postpartum rats, being 23 ± 1.4 μg. and 24 ± 1.9 ng. respectively, as compared to 15 ± 0.7 μg. in the nonpregnant rats.

The fetal pancreases were obtained at five periods of gestation: daily from day 18 to day 22, and on day 4 after birth. The mean weight of the fetal pancreases progressively and significantly increased from 4.4 ± 0.3 mg. on day 18 to 14.1 ± 1.5 mg. on day 20. On day 4 after birth, the mean pancreatic weight was 15.1 ± 0.5 mg. The fetal pancreatic insulin concentration rapidly and progressively increased from 14 ± 2 μg./gm. on day 18, to 80 ± 9 μg./gm. on day 21, and by day 4 after birth was 621 ± 103 μg./gm. By day 21 the fetal pancreatic insulin concentration had reached the prenatal peak and was already twice that of the mother. The total fetal pancreatic insulin content showed a progressive increase during the fetal life from 0.07 ± 0.01 μg. on day 18, to 1.23 μg. on day 21, a seventeen fold increase.

An estimate of the nutrients utilized for pregnancy by Merino sheep

1. Fifty-one pregnant fine-wool Merino ewes were slaughtered at intervals during pregnancy. The gravid uteri were dissected and were separated into uterus, membrane and fluid, and foetus fractions, which were analysed separately for water, nitrogen, ash, fat, calcium, phosphorus, sodium and potassium content.

2. Uteri from twenty-one similar non-pregnant ewes were also analysed for these constituents.

3. A number of relationships between the composition of the gravid uterus minus the composition of the uterus taken from non-pregnant sheep, and time from conception were calculated.

4. The rate of nutrient deposition was calculated from these relationships and estimates were made of the nutrients utilized for pregnancy.

Lipids of mineralizing epiphyseal tissues in the bovine fetus

Because lipids had been consistently detected histologically at sites of new calcification, the lipids of epiphyseal cartilage and bone in various stages of mineralization were examined. Lipids were extracted before and after demineralization and analyzed. Lipid content increased during proliferation and calcification of epiphyseal cartilage. Much less was seen in the adjacent cancellous bone; this corroborates histochemical findings. Similar phospholipid compositions were seen in the total lipids of cartilage and bone. Neutral (dipolar) phospholipids accounted for nearly 90% of the total lipid P and were almost completely extracted before demineralization. Serine- and inositol-containing phospholipids and two other, unidentified, acidic lipids could not be effectively extracted from calcifying tissues until after demineralization. Since the extraction of the acidic lipids was closely related to the degree of mineralization, it is possible that they form part of a lipoprotein-mineral complex in the calcifying matrix. Lysophospholipids were detected in all extracts, but primarily in those made after decalcification. It is concluded that acidic lipids are mainly responsible for the sudanophilia detected histologically at sites of new calcification.