Human Fetal Life Research Articles

Preferential utilization of conserved immunoglobulin heavy chain variable gene segments during human fetal life.

The ability to respond to specific antigens develops in a programmed fashion. Although the antibody repertoire in adults is presumably generated by stochastic combinatorial joining of rearranged heavy variable, diversity, and joining (VH-DH-JH) and light (VL-JL) chains, experimental evidence in the mouse has shown nonrandom utilization of variable gene segments during ontogeny and in response to specific antigens. In this study, we have performed sequence analysis of 104-day human fetal liver-derived, randomly isolated constant region C+ mu transcripts and demonstrate a consistent preference during fetal life for a small subset of three highly conserved VH3 family gene segments. In addition, the data show that this preferential gene segment utilization extends to the DHQ52 and the JH3 and JH4 loci. Sequence analysis of two "sterile" DH-JH transcripts suggests that transcriptional activation of the JH-proximal DHQ52 element may precede initiation of DH-JH rearrangement and influence fetal DH utilization. Sequence comparisons reveal striking nucleotide polymorphism in allelic gene segments which is poorly reflected in the peptide sequence, implying considerable evolutionary selection pressure. Although vertebrate species utilize a variety of strategies to generate their antibody repertoire, preferential utilization of VH3 elements is consistently found during early development. These data support the hypothesis that VH3 gene segments play an essential role in the development of the immune response.

Human Ontogenesis

The ultrastructural pattern of the early stages of end-plate formation is described in the quadriceps femoris muscle of 9- to 20-week-end human fetuses. Features of the neuromuscular junction are first observed in the ninth week of fetal life. The primitive motor end-plate contains a few axons always covered by one Schwann cell and does not seem to change either in number or in structure from the tenth through the twentieth week. Continuous modification of the post-synaptic apparatus is observed from the tenth to the twentieth weeks of human fetal life.

Some aspects of fetal laryngeal development.

Some aspects of morphological and physiological development of the fetal larynx are presented. Histochemical confirmation and determinations of fetal glandular activity are needed. Anomalous development of the larynx is still conjecture, but congenital cystic formation with glandular development appears possible after the fifth month of human fetal life.

Reaction of Infants to Aircraft Noise and Effect of the Noise on Human Fetal Life

Reaction of Infants to Aircraft Noise and Effect of the Noise on Human Fetal Life

Statistical studies on the effects of intense noise during human fetal life

In previous work [Y. Ando and H. Hattori 1970 Journal of the Acoustical Society of America 47, 1128–1130] the manner in which infants react to aircraft noise was investigated. It was found that babies born of mothers who came to a noisy area before or during the first five months of pregnancy showed little or no excitability to the noise. The subjects were 188 babies. In this report more than a thousand subjects including low-birth-weight infants were chosen to replicate previous work. Also, it was observed that the birth-rate of low-birth-weight babies increased as the noise level increased.

The Acidic Glycosaminoglycans in Human Fetal Development and Adult Life: Cornea, Sclera and Skin

A comparison was made of the concentration and composition of the acidic glycosaminoglycans in human cornea, sclera and skin during five to nine months fetal development and in the adult. In skin, the concentration of the acidic glycosaminoglycans decreases gradually duringfetal development; the adult value is still less than the newborn; hyaluronic acid and dermatan sulfate are always present. In sclera, during the same period of development the concentration of the acidic glycosaminoglycans varied little; dermatan sulfate is the main component in both fetus and adult but the latter also contains some hyaluronic acid and chondroitin 4(6)-sulfate. The concentration of the acidic glycosaminoglycans in cornea increased by 33% at seven months gestation and remained constant; fetal cornea has chondroitin 4(6)-sulfate, chondroitin and a small amount of keratan sulfate (18 to 27% of the acidic glycosaminoglycans); in contrast, the adult cornea is rich in keratan sulfate (64 % of the acidic glycosaminoglycans) a...

Immuno-cytochemical study on the development and differentiation of the immune system of the human fetus.

The lymphatic tissues of human fetus and infant were studied systematically from an immuno‐cytochemical view‐point. Among immunoglobulins, γA and γM first appeared in the primitive mesenchymal cells around the mesenteric and hepatic hilar vessels at the 11th fetal week. These cells were considered to be the primordium of the gut wall lymphoid tissues; the thymus and the bursa type tissue. γM in the reticular cells and γA in the medium‐sized lymphoid cells were identified in the thymus after the middle of fetal life. γG, maternal in origin, was observed in the eosinophilic cells, mostly in the thymus. After passing middle fetal life, these three types of immunoglobulins were found in the HassaU's corpuscles, increasing quantitatively toward the end of fetal life. The role of thymus in the development of the immune system during the human fetal life was discussed in relation to other lymphatic tissues.