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At least 1,009 records · Page 56Linked to original sources
PubMed2000

Embryonic and early fetal development of the human neocortex.

Early corticogenesis was studied in human embryos and early fetuses from Carnegie stages 16 to 22 (5-8 gestational weeks) by using immunohistochemistry for Reelin (Reln), calretinin (CR), and glutamic acid decarboxylase (GAD). A first population of Reln-positive cells appears in the neocortical anlage at stage 16 and increases in number at stages 17-18. At stages 19-20, a monolayer of horizontal CR- and GAD-positive, Reln-negative neurons forms in the preplate, whereas Reln-positive cells shift into a subpial position. Another cell class, the pioneer projection neuron, is CR-positive but GAD- and Reln-negative; pioneer cells contribute early corticofugal axons. Pioneer cells first appear below the monolayer at stage 20 and form a pioneer plate at stage 21. The cortical plate (CP) proper emerges at stage 21 and inserts itself within the pioneer plate, which is thus split into a minor superficial component and a larger deep component that presumably corresponds to the subplate. Initial CP neurons are radially organized and mostly CR-negative. Reln-positive cells remain consistently segregated from the pioneer cells and are thus not directly involved in preplate partition. Our data indicate that the neuronal composition of the human neocortical preplate is more complex than generally described and that various neurons participate in a sequence of events that precede the emergence of the CP.

Calbindin 2↗
PubMed1976

Ontogeny of the antibody-forming cell line in mice. II. Maturation of B cells during fetal development.

This paper maps the developmental stage reached by B cells in mouse fetuses of different ages. The "maturity" of these cells was assessed in a functional way by measuring the time taken for cells to generate antibody-forming progeny when injected into carrier-primed irradiated adult hosts and challenged daily with antigen. A steady uninterrupted progression in development of B cells occurred between 13 days of gestation and birth. There was no evidence for a stage during which B cells could only be paralyzed and not induced by antigen.

Animals↗
PubMed2001

[Fetal development and postnatal maturation of the longus colli muscle].

In adults, the predominant expression of a slow phenotype in the m. longus colli corresponds to its important postural function. Morphologically, there is a dispersion in fiber size predominating on the fast type 2 fibers which are significantly smaller than the slow type 1 fibers. We deemed it of interest, therefore, to analyze the metabolic differentiation of the muscle longus colli during its development. This study has been carried out on six anatomical samples, in foetuses aged between 16 and 40 weeks of pregnancy and in an 18 month-old child. The histological study combined H&E staining and immunohistochemical techniques (using antibodies specific for the slow and the fast isoforms of the myosin heavy chains). Our results indicate that the m. longus colli differentiates during the foetal period in a way which is quite comparable to that of other skeletal muscles, such as the quadriceps. In this series, a major slow predominance with a significant dispersion in fiber size was first observed in the 18 month-old child. Thus, it can be concluded that the establishment of the adult phenotype of this muscle starts during postnatal life, following the development of the mechanisms holding up the head and neck and leading to the appearance of the cervical lordosis.

Gestational Age↗
PubMed1995

[The formation of the child in the womb reproduction and fetal development in medieval Arabic-Islamic medicine].

In the following survey of theories of reproduction and pre-natal development in medieval Arabic medicine, the first part outlines the historical and methodological premises, indicates the major Greek sources (Corpus Hippocraticum, Aristotle, Galen) and introduces the Arabic texts relevant to the subject. In the second part three examples taken from Ibn Sīnās' Canon medicinae are presented to substantiate the supposition that the particular contribution of medieval Islam in the field of reproduction (which continued into the Latin Middle Ages) lay in the merging and harmonisation of data of various origins and concepts developed in different explanatory contexts within the Greek tradition.

Arab World↗
PubMed2003

[Analysis of growth model in vestibular aqueduct during human fetal development].

OBJECTIVE: To characterize the growth of the developing vestibular aqueduct in order to gain a better understanding of the possible origins of enlarged vestibular aqueduct. METHODS: Serial sections from 32 temporal bones for every other week from human embryos ranging in age from 6 to 38 weeks were studied with 3DMed medical image analysis software. The internal, external aperture, midpoint diameter and length vestibular aqueduct were analyzed with regression analysis to obtain a growth curve. RESULTS: The internal aperture of vestibular aqueduct was began to form at 6 weeks' gestation. It grew to reach the posterior surface of the petrous bone in the posterior cranial fossa by 10 weeks' gestation. All width parameter mean value in our embryos nerve reached the maximum average width in the adult. Statistical analysis showed that the vestibular aqueduct grew in a nonlinear continuous fashion and instability trend throughout embryonic life, except length parameter. CONCLUSION: The vestibular aqueduct grows in a nonlinear fashion throughout embryonic life. The widest aqueduct measured in embryonic life does not reach the maximum average width in the adult. These results suggest that it would be possible for vestibular aqueduct to develop postnatally.

Anthropometry↗
PubMed1992

Cholinergic reactivity of cerebral arteries in the developing fetal and newborn lamb.

Cerebral arteries of newborn pigs and baboons constrict to acetylcholine, suggesting that endothelium-dependent dilator mechanisms may be lacking in immature cerebral arteries. The present study tested this possibility in the immature sheep by examining the response of cerebral arterioles in fetal and newborn sheep to endothelium-dependent dilator, acetylcholine. Pial arteriolar diameter was measured in 9 anaesthetized foetuses in utero (4 preterm, 90-111 days gestation and 5 term, 128-143 days gestation) and in 5 anaesthetized, newborn lambs (14 days) using a closed cranial window with intravital microscopy. Application of acetylcholine to the pial surface induced dose-dependent increase in pial arteriolar diameter in all age groups; EC50 for acetylcholine was 0.10 +/- 0.03, 0.28 +/- 0.08 and 0.26 +/- 0.17 microM for preterm fetal, term fetal, and newborn lambs, respectively. The data demonstrate a sensitive dilator response to acetylcholine in immature fetuses as well as newborn lambs suggesting that cholinergic-mediated release of endothelium-dependent relaxing factor is functional early in gestation. The contractile response to acetylcholine observed in newborn pigs and premature baboons may reflect a species difference rather than maturational lack of endothelium-dependent dilator mechanisms.

Acetylcholine↗
PubMed1989

Level of termination of the spinal cord during normal and abnormal fetal development.

The level of termination of the spinal cord in 115 autopsies on subjects ranging from a 20-week stillborn to an 8-month-old infant is reported. The study showed that the adult level (lower border L1) is attained at birth. In a clinical study of 10 children with diastematomyelia between the ages of 3 years and 7 years the spinal cord, which was found to terminate in the region of the lower lumbar spine, was tethered by a short thickened filum terminale.

Black People↗
PubMed1985

Cardiovascular and respiratory agents during pregnancy: implications for fetal development.

The management of common medical problems in pregnancy often requires adjustments in drug therapy to assure a healthy fetus. The management of steroid-dependent bronchial asthma in pregnancy requires oxygen supplementation as well as vigorous treatment of airway obstruction to protect the fetus from maternal hypoxemia. The hypertensive pregnant patient should discontinue dietary sodium restriction and diuretic therapy and should be managed with alphmethyldopa or beta-blocker therapy. Hydralazine may be added if hypertension is severe. Mitral valve prolapse appears to produce no difficulties during pregnancy and the use of prophylactic antibiotics is probably not necessary for routine vaginal delivery, unless complications occur. Digoxin and quinidine are safe to use in pregnancy, provided careful monitoring is maintained. Oral anticoagulants are contraindicated in pregnancy and should be replaced with heparin if pregnancy is desired.

Adrenergic beta-Antagonists↗