The origin of the turtle plastron is not known, but these nine bones have been homologized to the exoskeletal components of the clavicles, the interclavicular bone, and gastralia. Earlier evidence from our laboratory showed that the bone-forming cells of the plastron were positive for HNK-1 and PDGFRalpha, two markers of the skeletogenic neural crest. This study looks at the embryonic origin of these plastron-forming cells. We show that the HNK-1+ cells are also positive for p75 and FoxD3, confirming their neural crest identity, and that they originate from the dorsal neural tube of stage 17 turtle embryos, several days after the original wave of neural crest cells have migrated and differentiated. DiI studies show that these are migratory cells, and they can be observed in the lateral regions of the embryo and can be seen forming intramembranous bone in the ventral (plastron) regions. Before migrating ventrally, these late-emerging neural crest cells reside for over a week in a carapacial staging area above the neural tube and vertebrae. It is speculated that this staging area is where they lose the inability to form skeletal cells.

Background: Fetomaternal hemorrhage (FMH) is a poorly understood condition in which the placenta allows transmission of fetal whole blood to the mother. FMH can cause fetal anemia resulting in critical illness, death or lifelong disability. Ascertainment of the incidence of FMH is limited by reliance on retrospective studies that are dependent on a diagnosis of FMH being made at the time of patient presentation. Objective: To determine whether the diagnosis of FMH is made more frequently after an educational intervention to increase physician awareness of the condition. Methods: This is a retrospective cohort study of all neonates born at our institution from 1988 through 2010. The medical records of all neonates diagnosed with anemia in the first 24 h of life were reviewed. The incidence of FMH as a documented etiology of anemia was compared between infants born before and after our educational intervention. Results: Of 124,738 births during the study period, 572 neonates with neonatal anemia were identified. A total of 23 cases of FMH demonstrated by positive Kleihauer-Betke testing occurred in our cohort. The incidence of diagnosed FMH prior to our intervention was 22 per 1,000 anemic neonates compared to 182 per 1,000 afterwards (p < 0.001), while the incidence of neonatal anemia remained unchanged (p = 0.377). Conclusions: FMH may be a significant cause of neonatal anemia. Diagnosis of FMH is highly dependent on physician awareness of the condition. Incorrect or absent diagnosis of the etiology of neonatal anemia has significant implications for our understanding of the epidemiology of FMH.

Background Fetomaternal hemorrhage (FMH) is a poorly understood condition in which fetal erythrocytes transfer to the maternal circulation via a faulty placental barrier. Little is known about the true incidence, epidemiology, or pathophysiology of FMH in the general pregnant population as existing studies are based on retrospective cohorts and manifest diagnosis and selection bias. Objective To evaluate the practicability of a prospective study of fetomaternal hemorrhage in the general population based on antepartum maternal blood testing and neonatal anemia. Study Design Prospective cohort study. Result Nineteen pregnant women were enrolled prior to the term delivery of twenty well infants. Five neonates were unexpectedly anemic on first postnatal testing. Antenatal maternal blood samples associated with 2 of 5 anemic newborns had positive Kleihauer-Betke testing while no newborn with a normal postnatal blood count had an associated abnormal Kleihauer-Betke test. Conclusion Clinically significant FMH may be more common than previously thought. Prospective epidemiological study of FMH is feasible.

Background: Fetomaternal hemorrhage (FMH) signifies failure of the placental barrier with whole blood transfer. Fetal anemia following FMH is associated with significant morbidity and mortality. If FMH is identified early, fetal anemia can be treated to minimize adverse outcomes. Risk factors for FMH are not known, limiting efforts to provide targeted screening for FMH. Objective: To identify maternal and/or pregnancy characteristics associated with FMH that are recognizable prior to fetal morbidity. Methods: This is the first published case-control study of FMH. Cases were identified from a prospectively maintained database of all hospital births between 1988 and 2010. Each case was matched to 4 controls by date and time of birth, allowing for assessment of a wide range of clinical and demographic data. Logistic regression modeling was used to assess the association between demographic and clinical characteristics and the diagnosis of FMH. Results: A total of 23 mother-baby pairs impacted by FMH and 92 matched controls were evaluated. Compared to controls, case mothers were more likely to have private insurance and to work outside the home and at night during pregnancy. Cases were more likely to be delivered preterm, but preterm labor was not more common among cases. There was no difference in race/ethnicity of cases compared to controls. Conclusions: Severe FMH is associated with significant morbidity and mortality of the affected neonate. Women with FMH were more likely to work outside the home during pregnancy than women with normal pregnancies. This finding has implications for third-trimester screening of pregnant women who work in strenuous fields.

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