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Hemostasis development in the lamb fetus and neonate
1Laboratory of Hematology, CHR Trousseau, Faculty of Médecine, Tours, France.
American Journal of Veterinary Research
|January 1, 1989
Summary
Fetal lamb hemostasis shows similar platelet counts and coagulation to adults. Key vitamin K-dependent clotting factors gradually increase during gestation, reaching adult levels by birth.
Area of Science:
- Comparative physiology
- Hematology
- Perinatal medicine
Background:
- Hemostasis in fetal and neonatal mammals is not fully understood.
- Developmental changes in coagulation and fibrinolysis are critical for survival.
Purpose of the Study:
- To investigate the developmental hemostasis in fetal and neonatal lambs.
- To compare fetal and neonatal hemostatic parameters with adult sheep.
Main Methods:
- Studied hemostasis from day 60 of gestation to birth in lambs.
- Assessed platelet counts, recalcification time, and thromboelastography.
- Measured coagulation factors (II, VII, IX, X, V, VIII, XII), fibrinogen, protein C, and antithrombin III.
Main Results:
- Platelet counts and basic coagulation tests were similar across fetal, neonatal, and adult sheep.
- Vitamin K-dependent factors (II, VII, IX, X) increased from 30-40% to 40-60% of adult values near term.
- Fibrinogen and Factor V reached adult levels at birth, while Factors VIII and XII increased gradually throughout gestation.
- Fetal fibrinolytic activity increased, independent of detectable tissue-type plasminogen activator or its inhibitor.
Conclusions:
- Fetal and neonatal lamb hemostasis exhibits distinct developmental patterns, particularly for vitamin K-dependent factors.
- The liver's role in synthesizing coagulation factors and potential vitamin K deficiency are important considerations.
- Increased fetal fibrinolytic activity suggests complex regulatory mechanisms during development.