Our current knowledge of brain growth in non-human primates is based on comparisons of brain weights in cadaveric newborns compared to adults. Previous work has revealed most strepsirrhine primates (e.g., lemurs and lorises) defer much of their brain growth to the postnatal timeframe. No studies have examined brain growth across postnatal ages, to determine when adult brain size is achieved relative to life history milestones such as weaning or eruption of adult dentition. Micro-computed tomography via a Scano vivaCT 75 was utilized to scan six specimens, ranging from newborn (day 0) to adult. Amira software was then used to manually segment endocranial contours and generate endocranial volumes from each of the specimens. Preliminary data indicates that the neonatal Galago possesses roughly 44% of the endocranial volume of its adult counterpart. By the late infant stage (30 days), the Galago possesses roughly 70%, and by 60 days postnatal, 99% of the adult endocranial volume. This timeline precedes the weaning period seen at roughly 90 days. Other milestones are also reached at the same age. Galago is reported to be perfecting its signature leaps at 60 days, and in our sample, more than half of replacement teeth have erupted. Results do suggest that Galago, like other strepsirrhines, defers most brain growth to postnatal ages. But here, for the first time, we demonstrate a rapid increase in endocranial volume, well before complete feeding independence.

Natural and artificial endocasts have been used for decades to enable researchers to visualize the endocranial space and approximate the morphology of internal soft tissue structures. Producing an endocast of the newborn primate skull is made difficult by the large fontanelle spaces between growing bones. As there is no definitive endocranial boundary, these spaces have the potential to introduce error into both manual and semi-automatic methods of endocast reconstruction. This study examines three methods of capturing endocranial volume (EV) from the endocasts of multiple species of newborn primates. For each specimen an EV was produced using three methods: a) manual, b) semi-automatic and c) "patched" semi-automatic segmentation. Manual segmentation is considered the "gold standard" of endocast reconstruction, however it lacks the efficiency of semi-automatic methods. The "patched" method proposed here is a novel approach to fontanelle closure that is accomplished using the "Baffle Planner" module in 3DSlicer, an open-access post-processing software that is freely accessible to all researchers. The interosseous patches constructed from user-defined landmarks are placed around the ossifying edges of the fontanelle and reflect the curvature of adjacent bones. In this study we provide guidance for optimizing the parameters of newborn primate endocast reconstruction in open-access software. Our study found both quantitative and qualitative differences between the models produced by these methods suggesting the chosen method of reconstruction affects the resulting EV measurement. We conclude that a patched semi-automatic approach with minimal baffles appears to reflect the anatomy with sufficient accuracy, while increasing efficiency and repeatability.

Diffusible iodine-based contrast-enhanced computed tomography (diceCT) has emerged as a viable tool for discriminating soft tissues in serial CT slices, which can then be used for three-dimensional analysis. This technique has some potential to supplant histology as a tool for identification of body tissues. Here, we studied the head of an adult fruit bat (Cynopterus sphinx) and a late fetal vampire bat (Desmodus rotundus) using diceCT and µCT. Subsequently, we decalcified, serially sectioned and stained the same heads. The two CT volumes were rotated so that the sectional plane of the slice series closely matched that of histological sections, yielding the ideal opportunity to relate CT observations to corresponding histology. Olfactory epithelium is typically thicker, on average, than respiratory epithelium in both bats. Thus, one investigator (SK), blind to the histological sections, examined the diceCT slice series for both bats and annotated changes in thickness of epithelium on the first ethmoturbinal (ET I), the roof of the nasal fossa, and the nasal septum. A second trial was conducted with an added criterion: radioopacity of the lamina propria as an indicator of Bowman’s glands. Then, a second investigator (TS) annotated images of matching histological sections based on microscopic observation of epithelial type, and transferred these annotations to matching CT slices. Measurements of slices annotated according to changes in epithelial thickness alone closely track measurements of slices based on histologically-informed annotations; matching histological sections confirm blind annotations were effective based on epithelial thickness alone, except for a patch of unusually thick non-OE, mistaken for OE in one of the specimens. When characteristics of the lamina propria were added in the second trial, the blind annotations excluded the thick non-OE. Moreover, in the fetal bat the use of evidence for Bowman’s glands improved detection of olfactory mucosa, perhaps because the epithelium itself was thin enough at its margins to escape detection. We conclude that diceCT can by itself be highly effective in identifying distribution of OE, especially where observations are confirmed by histology from at least one specimen of the species. Our findings also establish that iodine staining, followed by stain removal, does not interfere with subsequent histological staining of the same specimen.

Diffusible iodine-based contrast-enhanced computed tomography (diceCT) has emerged as a viable tool for discriminating soft tissues in serial CT slices, which can then be used for three-dimensional analysis.This technique has some potential to supplant histology as a tool for identification of body tissues.Here, we studied the head of an adult fruit bat (Cynopterus sphinx) and a late fetal vampire bat (Desmodus rotundus) using diceCT and µCT.Subsequently, we decalcified, serially sectioned and stained the same heads.The two CT volumes were rotated so that the sectional plane of the slice series closely matched that of histological sections, yielding the ideal opportunity to relate CT observations to corresponding histology.Olfactory epithelium is typically thicker, on average, than respiratory epithelium in both bats.Thus, one investigator (SK), blind to the histological sections, examined the diceCT slice series for both bats and annotated changes in thickness of epithelium on the first ethmoturbinal (ET I), the roof of the nasal fossa, and the nasal septum.A second trial was conducted with an added criterion: radioopacity of the lamina propria as an indicator of Bowman's glands.Then, a second investigator (TS) annotated images of matching histological sections based on microscopic observation of epithelial type, and transferred these annotations to matching CT slices.Measurements of slices annotated according to changes in epithelial thickness alone closely track measurements of slices based on histologically-informed annotations; matching histological sections confirm blind annotations were effective based on epithelial thickness alone, except for a patch of unusually thick non-OE, mistaken for OE in one of the specimens.When characteristics of the lamina propria were added in the second trial, the blind annotations excluded the thick non-OE.Moreover, in the fetal bat the use of evidence for Bowman's glands improved detection of olfactory mucosa, perhaps because the epithelium itself was thin enough at its margins to escape detection.We conclude that