Human fetal lung morphometry at autopsy with new modeling to quantitate structural maturity

• Published in: Pediatric pulmonology Vol. 52; no. 6; pp. 771 - 778
• Main Author: Lipsett, Jill
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.06.2017
• Subjects: Autopsy; Fetus - anatomy & histology; Humans; Lung - anatomy & histology; pulmonary development morphometry; pulmonary development morphometry
• ISSN: 8755-6863; 1099-0496; 1099-0496
• DOI: 10.1002/ppul.23675

OBJECTIVES To demonstrate a simplified morphometric procedure, including a new model for acinar structural maturity, applicable to autopsy fetal lung and present reference values for these parameters. STUDY DESIGN Cases with autopsy consent for research were studied. To simplify analysis only critical morphometric parameters were measured to allow calculation of gas‐exchange surface area. SUBJECT SELECTION A total of 58 fetuses, 16‐40 weeks were included. Subjects were rejected with any condition predisposing to pulmonary hypo/hyperplasia, significant maceration, or if lung weight/bodyweight or microscopy identified pulmonary hypoplasia or lung growth disorders. METHODOLOGY Lungs were inflation fixed, weights and volumes determined, sampled, then returned to the body. Volume densities (VV) of parenchyma/non‐parenchyma and air‐space/gas‐exchange tissue, gas‐exchange surface density (SV), and total surface area (SA) were determined. The number, mean radius, and septal thickness of modeled airspace‐spheres were calculated. Equations were generated for each parameter function of gestation and bodyweight. RESULTS From 16 to 40‐week weights and volumes increased as power functions from ∼4 g/mL to ∼90 g/mL. Parenchyma/non‐parenchyma changed little—75:25 (16 weeks) to 71:29 (term). Parenchyma was 10% airspace:90% tissue early and 50:50 by term. Gas‐exchange SV increased from 175 to 450 cm2/cm3 and total SA increased from 0.059 to 4.793 m2. There were 3.31 × 106 airspace‐spheres, 12 µ radius, septal thickness 30 µ at 16 weeks, increasing to 56.92 × 106, 26 µ radius, septal thickness 13 µ by term. CONCLUSIONS Morphometry can feasibly be performed at autopsy, providing more informative quantitative data on lung structural development than current methods utilized. This reference data set compares well with published data.