Prenatal ossification in rabbits as indicative of fetal maturity.

During the prenatal period of development of the rabbit skeleton (days 21-30) the successive phases of fetal maturity can be distinguished by reference to the progress of ossification, particularly in the distal limbs and sternum. In the present study absent or incomplete ossification of sternebra 5 occurred in 8% of term fetuses. The incidence of anomalies of prenatal ossification of the axial skeleton was 1.9%. The relevance of delayed and disturbed ossification with regard to teratological tests is discussed.     

Distribution of CAIII in fetal and adult human tissue

Carbonic anhydrase III (CAIII), an enzyme recently shown by conventional electrophoresis to be muscle specific, has been quantitated by “rocket” immunoelectrophoresis. This more sensitive technique has shown that the enzyme is virtually specific to skeletal muscle, where it occurs at a level of 5mg/g, with trace levels in smooth muscle, cardiac muscle, and lung. In man there does not appear to by any correlation between CAIII levels and the proportion of red and white muscle fibers. The fetal development of CAIII has also been examined using immunoelectrophoresis, and the enzyme can be detected at 11 weeks' gestation. The CAIII level rises gradually up to 25 weeks, and there is then a more dramatic increase to reach approximately half adult level at birth.     

Stimulation of cholinogenesis in human fetal nerve cell cultures

The aim of the study was to obtain a neural cell population enriched in culture with cholinergic neurons and their determined precursors. It has been established that the joint application of retinoic acid and acetylcholine appears to be the most efficient combination of neuroinductors, stimulating the differentiation of cholinergic neurons from neural stem cells. During the entire period of culturing, the amount of ChAT⁺-positive cells increased reliably to 21.1 ± 6.2% from 5.3 ± 2.9, whereas the ir concentration in the control samples was 9.1 ± 4.8% of the total cell count. The cell population enriched with cholinergic neurons and their determined precursors correlated well with the increased acetylcholinesterase activity. Thus, the addition of retinoic acid and acetylcholine stimulate both neurogenesis and cholinogenesis in human fetal neural stem cell cultures.     

Fascin expression in human embryonic, fetal, and normal adult tissue.

This study investigates the distribution of fascin in human embryonic, fetal, and normal adult tissues. Tissue microarray technology was used to perform immunohistochemical experiments on human embryos and fetuses at 4-22 weeks of gestation and adult specimens. Fascin was widely expressed in the nervous system. At 4 weeks of gestation, fascin was present in the neural tube. At 8-12 weeks of gestation, homogenous gene expression was seen in cells of the cerebellum and gastrointestinal tract. In later developmental stages and in adults, Purkinje cells of the cerebellum and glandular epithelium of the gastrointestinal tract showed no expression. Fascin was expressed in the cortex and medulla of the adrenal gland at 8-12 weeks of gestation, whereas immunoreactivity decreased from the zona glomerulosa through the zona reticularis and was essentially negative in the adrenal medulla of adults. Significant expression of fascin was seen throughout development in neurons, follicular dendritic cells of lymphoid tissue, basal layer cells of stratified squamous epithelia, mesenchyme, and vascular endothelial cells. Simple columnar epithelia of the biliary duct, colon, ovary, pancreas, and stomach were all negative for fascin expression. These results show that expression of fascin is time specific and highly tissue specific. Parallels between fascin expression in embryogenesis and carcinogenesis are discussed.     

Characterisation of immunoreactive somatostatin in human fetal hypothalamic tissue

Levels of immunoreactive somatostatin (IRS) were measured in extracts of hypothalamic tissue from human fetuses of 12–26 weeks gestation. The IRS contents (0.7–22.5 ng) and concentrations (2.7–118.0 pg/mg wet weight tissue) both increased slightly with gestation. Sephadex G-50 chromatography of 11 extracts showed up to four peaks of IRS, one co-eluting with synthetic somatostatin-14 (S14), a second co-eluting with synthetic somatostatin-28 (S28) and two other peaks having approximate molecular weights of 6000 and 10 000, respectively. The levels of S14 and S28 increased significantly during gestation, while the levels of 6000 molecular weight IRS decreased with age. We suggest that the increase in S14 and S28 levels may be the cause of the fall in circulating growth hormone (GH) in the fetus in later gestation.     

Maintenance of fetal human pancreatic beta cells in tissue culture

Large quantities of viable human islet tissue (beta cells) are required for transplant and for investigations of the autoimmune basis of Type I diabetes. Fetal pancreas offers a potential advantage over other possible sources of beta cells in that it retains some capacity for growth in vitro. We have cultured a total of 45 human pancreata from fetuses of gestational ages from 18 to 23 weeks. Each pancreas was obtained within minutes after delivery and usually cultured within 30 minutes. Pancreata were dispersed and cultured for up to 32 days. Maintenance and growth of the beta cells was assessed by the content of insulin in extracts of cultured tissue. As has been reported by others, fetal human beta cells survived in vitro for over 4 weeks. In three experiments in which a direct comparison was made, collagenase digestion of the fetal pancreas resulted in a significantly greater loss of insulin content compared to minced tissue cultured without digestion. Storage of three pancreata in medium overnight at 4 degrees C significantly reduced the insulin content of the pancreas compared to pancreata cultured immediately. During culture, the majority of the beta cells (based on insulin content) were found in small, macroscopic clumps attached to the surface of the culture dish, and surrounded by a nearly confluent monolayer of fibroblastoid cells. There was a marked decrease in the insulin content of the tissue during culture, most of it (to less than 25% of the original) occurring over the first 4-6 days of culture.(ABSTRACT TRUNCATED AT 250 WORDS)     

Expression of fetal antigens by normal human skin cells grown in tissue culture.

Normal human sera are capable of causing complement-mediated lysis of normal human skin cells grown in tissue culture. This lytic reactivity can be completely removed by absorption with first trimester fetal tissue. Absorption with a variety of normal adult human tissues including lymphocytes, decidua, skin, and muscle are incapable of absorbing reactivity. Absorption of reactivity by fetal tissue is specific and not due to the introduction of anti-complementary or other nonspecific factors, as evidenced by the inability of simultaneous fetal absorption to remove reactivity from antisera with specificity for HLA antigens. Similarly, absorption of lytic sera with fetal calf serum proteins was incapable of removing reactivity against normal cells in tissue culture. It thus appears that normal human cells in tissue culture express antigens shared by the first trimester human fetus, but not present on a variety of adult human tissues. This "neoantigen" present on normal human cells when grown in tissue culture is a potential source of confusion and must be accounted for in searching for human tumor-specific antigens utilizing tissue culture cells.     

Ethics of fetal tissue transplantation.

Now that the Clinton Administration has overturned the ban on federal funding for fetal tissue transplantation, old ethical issues renew their relevance and new ethical issues arise. Is fetal tissue transplantation necessary and beneficial? Are fetal rights violated by the use of fetal tissue in research? Is there a moral danger that the potential of fetal tissue donation will encourage elective abortions? Should pregnant women be allowed to designate specific fetal transplant recipients? What criteria should be used to select fetal tissue transplants? Whose consent should be required for the use of fetal tissue for transplantation? We review the current state of clinical research with fetal tissue transplantation, the legal history of fetal tissue research, the major arguments against the use of fetal tissue for transplantation, and the new postmoratorium ethical dilemmas. We include recommendations for guidelines to govern the medical treatment of fetal tissue in transplantation.     

Specificities of heterologous antisera against human leukaemia cells. 2. Reactions against fetal liver cells and absorption studies with fetal tissue.

Rabbit or goat antisera directed to ALL and AML cells were investigated in cytotoxicity tests with fetal liver cells as targets. After absorption with erythrocytes and spleen cells from allogenic donors the antisera killed fetal liver cells. There was no reaction with remission leukocytes or blood leukocytes from normal donors. Treatment with fetal tissue removed the activity of the AML and ALL antisera against ALL cells but not of the AML antisera against AML cells. This indicates the existence of at least two antigens on the surface of AML cells, one antigen is common with ALL cells and of fetal origin and another one seems to be characteristic of AML cells and not of fetal origin. Because treatment with fetal tissue removed all activity of the ALL antisera it can be assumed that leukaemia-associated antigens on ALL cells are of fetal origin.     

Degeneration of osteoblasts involved in intramembranous ossification of fetal rat calvaria

Summary Ossification of calvariae from day-21 rat fetuses was reinvestigated by electron microscopy using different fixation techniques (glutaraldehyde/OsO₄, tannic acid, ruthenium red, K-pyroantimonate). An osteoid layer with scattered mineral deposits was found at the mineralization front. Directly beyond this layer, a sheet of one to two layers of necrotic and degenerating osteoblasts was present. Above this sheet, normal and healthy cells were seen, formed by six to eight layers of flattened cells, embedded in a collagenous matrix. The osteoblasts on the less mineralizing opposite side of the calcified cavariae and the osteocytes embedded in the calcified calvariae appeared healthy. Closer inspection of the necrotic zone revealed apatite crystal in vesicles which most probably originated from mitochondria of the degenerated cells. Large K-pyroantimonate deposits were found throughout the osteoid and the necrotic zone, whereas only small granules were scattered in the cytoplasm and at the plasma membrane of the healthy cells directly adjacent to the necrotic zone. A concept of intramembranous mineralization is outlined, according to which osteoblasts store enormous amounts of calcium, which are liberated by physiological cell death in the vicinity of the mineralizing front.     

Isolation of human nerve growth factor from placental tissue

Nerve growth factor (NGF) has been isolated from human placental tissue. Using the chicken embryo dorsal root ganglia assay, we determined levels of NGF activity for the amnion, placental cotyledons, cord serum, fetal serum, and maternal serum. The highest levels of NGF activity were measured in placental cotyledons. After homogenization and centrifugation of the placental cotyledons, the supernatant was sequentially chromatographed, at neutral pH, on Sephadex G-100, DEAE-11, and Sephadex G-150. A high-molecular-weight protein fraction (150,000), which contained all the biological activity, was isolated in this fashion. Analytical isoelectric focusing of this fraction revealed a basic protein component (pI 9.5) of the high-molecular-weight species. Assays for NGF activity of all protein components separated by analytical isoelectric focusing showed that NGF activity was associated only with the basic protein component. Correspondingly, preparative isoelectric focusing of the high-molecular-weight species yielded a basic protein with very high biological activity (1–3 ng per biological unit) that was immunochemically active against rabbit IgG made against mouse -NGF.To whom reprint requests should be addressed.