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At least 379 records · Page 21Linked to original sources
PubMed1999

Reconstitution of the B cell repertoire after bone marrow transplantation does not recapitulate human fetal development.

Immune reconstitution during bone marrow transplantation has been proposed to produce a fetal-type immune system. This characteristic may contribute to the relative immunodeficiency that occurs in the early post-transplant period. This review reappraises recent studies of immunoglobulin heavy chain genes produced by the recovering immune system. Comparison of these genes to those that are generated by fetal and adult B cells, demonstrates that there is no evidence to support the conclusion that adult lymphocytes in the graft reverse to a fetal stage of differentiation. In terms of lymphocyte diversity, the inadequacy of the recovering immune system is more likely to be explained by a combination of other factors - such as the delayed occurrence of somatic hypermutation and class switching, and clonal dominance.

Adult↗
PubMed1987

Fetal development of the tympanic part of the facial canal.

We studied human middle ears from Wittmaack's temporal bone collection in the ENT Department of the University of Hamburg. In the 12-week-old fetus, cells from the embryonic middle ear mesenchyme form a tiny semi-circle around the tympanic part of the developing facial nerve. During the following weeks, the production of fibrillar material increases until the facial nerve is surrounded by a dense fibrous semi-canal. Intramembranous ossification starts from ossification centers in the anlage of the membranous facial canal. Bone appears first in the form of spicules surrounded by osteoblasts. At this time, so-called aplastic areas (aplastische Zonen) can be identified between these spicules. Their importance in the latter occurrence of dehiscenses in the mature facial canal is discussed.

Bone Development↗
PubMed2003

Vascular endothelial growth factor and angiogenin levels during fetal development and in maternal diabetes.

We evaluated the concentrations of vascular endothelial growth factor (VEGF) and angiogenin in the umbilical cord blood from 14 fetuses with erythroblastosis or alloimmune thrombocytopenia and at birth from 28 preterm fetuses, from 42 healthy term fetuses, and from 24 term fetuses born to mothers with insulin-treated diabetes. A correlation appeared between VEGF and angiogenin levels (r = 0.44, p = 0.038). The gestational age correlated with both VEGF (r = 0.38, p = 0.0008) and angiogenin levels (r = 0.80, p = 0.0001). The concentration of VEGF was lower in fetuses born to mothers with insulin-treated diabetes than in the healthy term fetuses (p = 0.0028), but this difference was absent for angiogenin (p > 0.05). In conclusion, in umbilical cord plasma, a developmental increase was evident in concentrations of VEGF and angiogenin during the last trimester of gestation. That the umbilical cord VEGF level was lower in term fetuses born to mothers with diabetes than in term fetuses of healthy mothers may be associated with an aberrant fetal vascular development in diabetic pregnancies.

Diabetes Mellitus, Type 1↗
PubMed1995

Auditory brainstem response in sheep. Part I: Fetal development.

The Auditory Brainstem Response (ABR) was recorded from fetal sheep in utero between gestational ages of 111 days and 136 days (Normal gestation is 145 days). The ABR was detected at 111 days gestation (dGA) and morphology of the waveform improved rapidly from 116 to 123 dGA. At 123 dGA, the four vertex-positive peaks were similar to those observed in adult ewes. Thresholds of the ABR to clicks and tone bursts improved rapidly between 111 and 123 dGA. From 123 to 136 dGA, ABR thresholds continued to improve, but at a much slower rate. Latencies for the peaks also decreased during development from 111 to 136 days, with latencies for Waves III and IV showing a greater decrease than latencies for Waves I and II.

Animals↗
PubMed1996

Sequential changes of programmed cell death in developing fetal mouse limbs and its possible roles in limb morphogenesis.

Apoptotic cell death in the developing limb of mouse fetuses was examined sequentially on days 11-15 of gestation by means of Nile blue (NB) sulfate staining with special reference to its relation to limb morphogenesis. With some exceptions, programmed cell death (PCD) in the hand and foot was observed in the mesenchyme but not in the surface ectoderm. We found that during digital formation PCD begins at the proximal portion of the interdigital mesenchyme and subsequently expands distally. Therefore, the initial PCD that occurs in the interdigital zones may determine the proximal ends of digital separation and also contribute to the demarcation between the palm (sole) and digits (toes). During digital separation, the areas of PCD in the interdigital zones were found to become larger and expand distally on day 13, which may be necessary for the separation of digits and for determining the interdigital area to disappear. PCD in presumptive phalangeal joints was also found to proceed from proximal to more distal joints. The PCD in presumptive joints may be required for the separation of phalanges and metacarpal (metatarsal) bones and for the formation of joint cavities. In addition, intense PCD was observed in the radial (tibial) and ulnar (fibular) margins of the hand and foot plates for 4-5 days. Such PCD at marginal areas seems to prevent the formation of supernumerary digits (preaxial and postaxial polydactyly) and other digital malformations. Therefore, the timing when PCD commences and ends, the sites where PCD occurs, and the intensity, duration, and proximo-distal progress of PCD appear to be genetically determined, and the elimination of unnecessary cells by PCD may be essential for normal limb morphogenesis. The present findings also suggest that the normal progress of PCD in the hand and foot plates of rodent fetuses may prevent the formation of some limb malformations such as webbing fusion of digits, polydactyly, or cleft hand/foot.

Animals↗
PubMed1989

[Antenatal echographic measurement of the fetal cerebellum. Significance in the evaluation of fetal development].

The authors present a study based on ultrasound measurements for the growth of the fetal cerebellum from the 17th-39th week of amenorrhoea (710 measurements carried out on 293 fetuses). Regular growth of the cerebellum seems to be independent of other biometric parameters and also of the population studied. This has been demonstrated by comparing it with curves that have been made by other teams. It should give an extra feature in investigating fetal growth. Studying the cerebellum in 12 cases of severe intra-uterine growth retardation (below the third centile at birth) which were discovered and followed up in our department shows that cerebellum growth is not altered by intra-uterine growth retardation even in severe cases. Because of this it can be a reliable sign of whether the pregnancy has gone to term.

Anthropometry↗
PubMed1988

Ultrasonic assessment of pregnancy and fetal development in three species of macaque monkeys.

Serial ultrasonic assessments of gestational sac (GS) and fetal biparietal diameter (BPD) were performed in the Japanese monkey (Macaca fuscata fuscata), rhesus monkey (Macaca mulatta), and crab-eating monkey (Macaca fascicularis). In the Japanese monkey, GS increased linearly for 3-8 weeks, whereas BPD increased in a linear-quadratic manner over 8 weeks to term. Ultrasonic assessments of spontaneously aborted fetuses with BPD growth retardation and diagnosis of a pelvic chocolate cyst also were reported.

Animals↗
PubMed1987

[Heart weight of the cattle (Bos taurus L.) in the middle and late periods of fetal development].

The weight heart Y-weight body relationship was studied on 219 Black-White cattle fetuses (107 females and 112 males; weight range of 1000-31,300 g). 1. The relationship in the consecutive growth periods are described by the following regression equations: middle fetal period (IIa and IIb)--IIa (n = 88, weight range 1000-3490 g) logY = 0.97 logX -- 2.05, r = 0.96; IIb (n = 68, weight range 3500-7990 g) logY = 1.04logX -- 2.29, r = 0.89; -- late fetal period III (n = 63, weight range 8000-31,300 g) logY = 1.07logX -- 2.39, r = 0.98. 2. The relationship for all fetuses, together with I prenatal period (earlier work of these authors) examined is described by the regression equation (n = 287, weight range 80-31,300 g) logY = logX -- 2.13, r = 0.99 (r -- correlations coefficient). 3. The relative heart weights are attained: IIa -- 0.72%, IIb -- 0.71%, III -- 0.77%.

Animals↗