Hematologic reference values for the fetal long-tailed macaque (Macaca fascicularis).

Area of Science:

• Comparative Hematology
• Primate Reproductive Biology
• Fetal Development

Background:

• Establishing normative hematologic reference values during prenatal development is crucial for assessing fetal health.
• Macaque models are frequently used in biomedical research, necessitating accurate species-specific data.

Purpose of the Study:

• To define normative hematologic reference values in fetal macaques throughout prenatal development.
• To provide baseline data for experimental studies investigating prenatal hematopoietic or hematologic toxicity.

Main Methods:

• Complete blood counts (CBCs) were performed on 68 fetal macaque blood samples from 31 fetuses.
• Blood was collected via ultrasound-guided cardiocentesis between gestational day (GD) 80 and GD 150.
• Analysis included white blood cell differentials, red blood cell parameters, and platelet counts.

Main Results:

• Lymphocytes were the predominant white blood cells (WBCs); segmented neutrophils increased significantly around GD 130-140.
• Overall WBCs increased progressively, with a transient decline near GD 110.
• Red blood cells (RBCs), hemoglobin, and hematocrit rose linearly, while mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) declined; nucleated RBCs (NRBCs) diminished significantly by GD 110.
• Platelet counts remained stable; erythrocyte morphology showed polychromasia and anisocytosis.

Conclusions:

• Fetal macaque hematology exhibits distinct patterns throughout gestation, with similarities to human fetal development.
• These established reference values are vital for interpreting CBC data in macaque models.
• The findings support the application of this data in studies anticipating prenatal hematopoietic/hematologic toxicity.