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At least 973 records · Page 54Linked to original sources
PubMed1967

Globin composition and synthesis of hemoglobins in developing fetal mice erythroid cells.

Fetal mouse erythropoiesis proceeds initially in yolk-sac blood islands (8 to 12 days) and, subsequently, in liver (12 to at least 16 days). Yolksac cells synthesize three hemoglobins, Hb E(I), Hb E(II) and Hb E(III). Hb E(I) has x- and y-globin chains; Hb E(II) has alpha and y; HB E(III), alpha and z. No detectable beta-globin is formed in these cells. Liver erythroid cells form only adult hemoglobin, composed of alpha- and beta-chains.

Animals↗
PubMed2002

Fetal development of the human tympanic ossicular chain articulations.

OBJECTIVES: To obtain further knowledge on the morphogenesis of the articulations in the tympanic ossicular chain in humans. MATERIAL AND METHODS: In 25 temporal bones of human fetuses the structural development of incudomallear, incudostapedial and stapediovestibular articulations was studied. The chronological ages were between the 7th week (21 mm) and the 29th week (270 mm). RESULTS AND DISCUSSION: Incudomallear articulation showed diarthrosis and sellar joint characteristics. It showed a homogenous interzone in the 7th week of development, a three-layered interzone in the 8th week, the first cavitation signs in the 9th week and the presence of an articular cavity in the 10th week. The presence of a hyaline cartilage covering articular surfaces was observed starting in the 20th week of development. Incudostapedial articulation showed typical characteristics of a diarthrosis and spheroidal joint with a homogenous interzone at the 7th week, showing similar characteristics for 12 weeks, and completed its cavitation at the 16th week. We observed hyaline cartilage on articular surfaces from 29 weeks. Stapediovestibular articulation showed typical characteristics of syndesmosis. The annular ligament primordium derived from cartilage differentiation, both from stapedial footplate and from the surrounding otic capsule, into mesenchyme and its subsequent transformation into fibrous tissue, reaching definitive characteristics from the 12th week.

Body Patterning↗
PubMedDate not supplied

Expression of ARVCF in the human ganglionic eminence during fetal development.

ARVCF (armadillo repeat gene deleted in velocardiofacial syndrome) is a recently characterized member of the catenin p120 (ctn) subfamily of the armadillo repeat proteins. It is involved in modulation of cell-cell adhesion essential to many developmental processes including cellular rearrangement and migration. In the present study, by using specific immunohistochemical methods, strongly ARVCF-immunoreactive cells in a high packing density were found in the human ganglionic eminence (GE), a telencephalic structure which gives rise to precursor neurons of the striatum, the amygdala and the basal nucleus of Meynert. From 20 to 25 weeks of gestation, stripes of immunoreactive cells were found to extend from both the superior part of the GE towards the intermediate zone of the neocortex and from the inferior part of the GE either towards the amygdaloid complex or more laterally towards the intermediate zone. Bands of ARVCF-positive cells were also identified in the gangliothalamic body, a transient target for the migrating neurons from the GE to the thalamus. Double immunolabelling with ARVCF and calretinin antibodies, which mark the GE neurons migrating towards the cerebral cortex, revealed that a majority of ARVCF-positive neurons at the periphery of the GE and the cellular extensions from the GE also expressed calretinin. Our results implicate a very close association of ARVCF with migrating neurons from the GE.

Armadillo Domain Proteins↗
PubMed2006

Fetal sheep development on ultrasound and magnetic resonance imaging: a standard for the in utero assessment of models of congenital abnormalities.

OBJECTIVE: To establish normative data for the size, conspicuity, and imaging characteristics of normal developing fetal sheep organs on ultrasound (US) and magnetic resonance (MR) imaging. METHODS: US and MR images of ten normal pregnant sheep, at 40, 65, 90, 115, and 140 gestational days (term = 145 days), were scored for organ conspicuity and imaging characteristics. Imaging biometry was correlated with specimens. Gestational age-based growth parameters were modeled using regression. RESULTS: Imaging biometry showed excellent correlation with specimens. Kidney, bladder, stomach, lung, liver, and spine were seen well from 65 days to term by US. More organs were consistently visible from 90 days to term by MR than by US. Most organ imaging characteristics tended not to change throughout gestation. CONCLUSION: Normal fetal sheep biometry, organ conspicuity, and imaging characteristics are established for US and MR and have potential use for the in utero assessment of sheep models of congenital abnormalities.

Animals↗
PubMed1980

Neuronal deficits in mice following phenobarbital exposure during various periods in fetal development.

Four groups of pregnant mice were fed milled food containing 3 g/kg phenobarbital, acid form, and water as their only nutritional source during various periods during pregnancy (days 9-18, 9-13, 13-16 or 16-18). Control females received milled food and water. The brains of control and phenobarbital-treated male offspring were removed at age 50 days, fixed, cut and stained with HE. Matching sagittal sections were sections were selected for the study of the cerebellar Purkinje cells and th hippocampal pyramidal cells. Previous findings were confirmed in that prenatal phenobarbital exposure during the last two trimesters of pregnancy (days 9-18) resulted in a long-lasting deficit in the number of the Purkinje (23%) and pyramidal cells 9% (P < 0.01). Phenobarbital administration during only part of this period (days 9-13, 13-16 or 16-18) had the same effect as administration during the entire period. The cell deficit did not correlate with the time of appearance of the neurons, thus, suggesting that phenobarbital may possibly act even on neurons which are already formed.

Animals↗
PubMed1991

Changes in lectin-binding patterns during late fetal development of the rat colon.

Lectin-binding and histochemical studies were integrated with a morphological description of colon development in rat fetuses to determine whether changes in glycoprotein sugars could be identified with stages of colon organogenesis. At 16 days gestation the colon consisted of a minute lumen surrounded by 3-5 layers of cuboidal, stratified epithelium, a basement membrane and undifferentiated mesenchyme. As development proceeded, epithelial spaces eventually fused with the main lumen, and fingers of mesenchyme, with a basement membrane and epithelial mantle, formed the walls of crypts lined with simple to stratified columnar cells. Goblet cells and mucin production appeared only on the 20th-21st day of gestation. Mesenchyme differentiation to a circular muscle band, the prospective tunica muscularis, occurred on days 17-18, and vascularization of the lamina propria was first detected on day 19. Wheat germ agglutinin (WGA) lectin bound avidly to sugar residues in the mesenchyme matrix from day 16 but weakened as the tissue differentiated, particularly into smooth muscle. Alcian blue staining of the matrix, also weakening with time, confirmed the sialic acid nature of binding sites for WGA on matrix acid mucopolysaccharides. Under controlled conditions, WGA also detected N-acetylglucosamine-binding sites on brush borders as they developed on the apical surface of primitive enterocytes. Ulex lectin bound to fucose residues of Alcian-blue-positive, PAS-positive mucin from the first appearance of goblet cells. Concanavalin A and glycine max lectins bound only to blood group substances on both nucleated red cells between days 16 and 19 and anucleate red cells from day 19.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Fetal development in relation to gestational age in the piglet.

Body and organ weights were measured in piglets from 44 litters which had been delivered by caesarean section at various times during the last 20 days of gestation. An attempt has been made to assess the usefulness of these measurements as predictors of gestational age. In this series of animals there was a highly significant correlation between mean litter weight and age. However, a considerable degree of uncertainty about the true gestational age must be accepted if mean litter weight is to be used as the sole predictor: at a mean litter weight of 1 kg, the 95% confidence limits were found to be +/- 10.2 days. No extra information was afforded by the inclusion of the organ weight data one the mean litter weight was known.

Animals↗
PubMed1993

Chronotropic and dromotropic actions of acetylcholine on the developing fetal heart.

We studied the effect of acetylcholine (ACh), 1 x 10(-8) to 5 x 10(-7) M, on electrophysiologic characteristics of the isolated (Langendorf), perfused fetal canine heart. ACh induced concentration-dependent decreases in sinoatrial (SA) rate and recovery from overdrive pacing and in atrioventricular (A-V) conduction. These effects of ACh were greater in mid-gestation than late-gestation hearts. The effects of ACh were potentiated by inhibition of acetylcholinesterase by neostigmine, 1 x 10(-7) M, in the late- but not the mid-gestation fetal heart. Decreasing the pH of the perfusion solution from 7.3 to 6.8 potentiated the response to ACh of SA rate and A-V conduction more in mid- than in late-gestation hearts. The response to ACh of the late-gestation fetal canine heart is more sensitive to cholinesterase inhibition whereas the response of the mid-gestation heart is more sensitive to the action of ACh in the presence of acidosis.

Acetylcholine↗