Fig 1.
Control and IH-exposed neonatal Sprague-Dawley rat pups less than 12 hours of age.
Note that skin color of the pups under the hypoxic condition has a bluish tinge compared to that of control pups. Temperature of the ambient air for both control and experimental animals was controlled at approximately 25 degrees Celsius.
Fig 2.
Linear measurements estimate of the size of the maxilla and the mandible of rats.
A. Transverse view of the maxilla and the skull base: Intermolar width–distance between upper buccal cusp tips of the maxillary first molars; Palatal width–linear distance between the right and left interdental alveolar bone of the first and the second upper molars; Inter-Zygoma width–distance between the most posterior curvature of the zygoma; Maxilla length–distance between the middle of interdental alveolar bones of the upper central teeth and posterior nasal spine; B. Sagittal view of the mandible from approximately 45 degrees anterior and superior: Intercondylar width–distance connecting the midpoint of the right and left condylar heads; Mandible length–distance between the midpoint of the condylar head and interdental bone of the lower central incisors; Mandible height–longest distance between the lower and upper border of the ramus.
Table 1.
Dahlberg D values for measurement errors calculated on 5 skulls.
Fig 3.
Comparisons between control vs. IH on the levels of NE in blood.
NE levels in 3-week-old pups (30.0 ± 4.27 vs. 38.7 ± 1.07 for males and 23.3 ± 2.86 vs. 34.1 ± 2.54 for females); 4-week-old pups (36.7 ± 0.54 vs. 41.7 ± 1.12 for males and 33.2 ± 0.86 vs. 32.7 ± 3.10 for females); 5-week-old pups (35.6 ± 0.24 vs. 43.2 ± 1.27 for males and 41.2 ± 0.57 vs. 39.8 ± 2.29 for females). NE levels in blood tended to increase gradually with age, as shown particularly in control female pups (23.3 → 33.2 → 41.2 pg/mL).
Fig 4.
Body weight measurements on control (n = 7) and IH (n = 3) males were compared.
A catch-up growth in body weights was apparent at the 4th and 5th week time points.
Fig 5.
Weights of dry mandibles that show a significant difference between control and IH animals at 5 weeks.
Fig 6.
Differences in histology of the mandible between control vs. IH pups.
A. Immunohistochemical stain using tyrosine hydroxylase (TH) antibody. Sprouting TH-positive sympathetic nerve fibers indicated by arrows in the 20X view of bone section obtained from an IH-treated pup are evident. The area exhibits the osteochondral interface of an IH-treated mandible condyle. B. Condylar heads harvested from control and IH-treated male pups. IH condyle shows an increased TRAP activity with more osteoclasts (indicated by yellow arrows) in the region of interest. Scale bars in 20X panel = 100 μm. Scale bars in 4X panel = 500 μm.
Fig 7.
Morphometric comparisons between the control vs. IH groups in 3 (red), 4 (blue) and 5 (green) week old male pups.
Although means and standard errors are denoted as shown in each graph, non-parametric methods were used to test implications for small sample size. * < 0.05, ** < 0.01.
Fig 8.
Morphometric comparisons between the control vs. IH groups in 3- (red), 4- (blue) and 5- (green) week-old female pups.
Distribution-free statistical methods were used to test implications.