Tooth crown mineralization and mandibular stiffness in growing lemurs
Mano N; Vinyard CJ; Deleon VB; Smith TD
American Journal Of Physical Anthropology
2021
2021-03
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/" target="_blank" rel="noreferrer noopener"></a>
The chondrocranial key: development of the sphenoid bone in primates
It has been hypothesized that the human sphenoid bone is uniquely truncated, which in turn contributes to a reduction of forward midfacial growth. If so, the perinatal fusion of the intrasphenoidal synchondrosis (ISS) in humans may contribute to midfacial reduction. However, there is a lack of detailed knowledge on sphenoid development of non‐human primates. In this study, orientation and direction of growth of basicranial interface with the midface of late prenatal and early postnatal sphenoid development was examined in ontogenetic samples of primates including three species of monkeys (n = 25) and four species of lemurs and bushbabies (strepsirrhines; n= 28). Micro‐computed tomographic (CT) and histological methods were used to track cross‐sectional age changes in the sphenoid bone. In monkeys (Saguinus spp.), histological findings indicated the number of proliferating chondrocytes is reduced across age leading to a reduction in absolute anteroposterior length of the proliferating zone. Preliminary data from micro‐CT reconstructions suggest that absolute length of the ISS decreases more rapidly in monkeys than in strepsirrhines. Measurements of presphenoid (PS) and basisphenoid (BS) length indicate that in strepsirrhines, these bones grow similarly to one another as cranial length increases. In contrast, in monkeys, the PS increases at a faster pace (i.e. higher linear regression line slopes) than the BS. However, unlike humans, the monkeys studied have prolonged postnatal patency of the ISS. Thus, the reduced midfacial projection in humans and these monkeys cannot be explained by the timing of ISS fusion alone. Dichotomous growth patterns of the cranial base and midface among primates suggest different patterns of regional integration of the cranium. In particular, our results suggest that in monkeys, integration of the midface is stronger with the anterior compared to the posterior portion of the sphenoid bone. In strepsirrhines by comparison, growth of the midface progressively deviates from that of the sphenoid bone over time.
Mano N;Wood B;Oladipupo L;Reynolds RL;Vinyard CJ;Cray JJ;DeLeon VB;Smith T
Faseb Journal
2020
2020-04
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1096/fasebj.2020.34.s1.03412" target="_blank" rel="noreferrer noopener">10.1096/fasebj.2020.34.s1.03412</a>
Cranial synchondroses of primates at birth.
Development; Craniofacial; Perinatal; Chondrocranium
Cranial synchondroses are cartilaginous joints between basicranial bones or between basicranial bones and septal cartilage, and have been implicated as having a potential active role in determining craniofacial form. However, few studies have examined them histologically. Using histological and immunohistochemical methods, we examined all basicranial joints in serial sagittal sections of newborn heads from nine genera of primates (five anthropoids, four strepsirrhines). Each synchondrosis was examined for characteristics of active growth centers, including a zonal distribution of proliferating and hypertrophic chondrocytes, as well as corresponding changes in matrix characteristics (i.e., density and organization of type II collagen). Results reveal three midline and three bilateral synchondroses possess attributes of active growth centers in all species (sphenooccipital, intrasphenoidal, presphenoseptal). One midline synchondrosis (ethmoseptal) and one bilateral synchondrosis (alibasisphenoidal, ABS) are active growth centers in some but not all newborn primates. ABS is oriented more anteriorly in monkeys compared to lemurs and bushbabies. The sphenoethmoidal synchondrosis (SES) varies at birth: in monkeys, it is a suture-like joint (i.e., fibrous tissue between the two bones); however, in strepsirrhines, the jugum sphenoidale is ossified while the mesethmoid remains cartilaginous. No species possesses a SES that has the organization of a growth plate. Overall, our findings demonstrate that only four midline synchondroses have the potential to actively affect basicranial angularity and facial orientation during the perinatal timeframe, while the SES of anthropoids essentially transitions toward a "suture-like" function, permitting passive growth postnatally. Loss of cartilaginous continuity at SES and reorientation of ABS distinguish monkeys from strepsirrhines. This article is protected by copyright. All rights reserved. (This article is protected by copyright. All rights reserved.)
Smith TD;Reynolds RL;Mano N;Wood BJ;Oladipupo L;Hughes GK;Corbin HM;Taylor J;Ufelle A;Burrows AM;Durham E;Vinyard CJ;Cray JJ;DeLeon VB
Anatomical Record
2020
2020-10-04
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journalArticle
<a href="http://doi.org/10.1002/ar.24521" target="_blank" rel="noreferrer noopener">10.1002/ar.24521</a>
Histological changes in midline basicranial synchondroses across age in saguinus
Wood B; Corbin H; Taylor J; Vinyard CJ; Cray J; Deleon VB; Smith TD
American Journal Of Physical Anthropology
2021
2021-03
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/" target="_blank" rel="noreferrer noopener"></a>
The sphenoidal synchondroses: Implications for the midfacial growth of anthropoid primates
The basicranium of anthropoid primates is more flexed than in lemurs and lorises (strepsirrhines), which has implications for orientation of facial growth. Differential growth among cranial synchondroses is one suggested mechanism for variation in basicranial development. In this study, we measured length of bony elements of the cranial base using Amira software in a cross‐sectional age sample (late prenatal to juvenile), which included three monkey species and four species of lemurs and bushbabies (n = 59). In addition, we made preliminary measurements of the anteroposterior length of the spheno‐occipital synchondrosis (SOS), intrasphenoidal synchondrosis (ISS), and prespheno‐septal synchondrosis (PSept) using newborn samples. In order to assess differences in growth potential among sync hondroses, the diameter of the proliferating (PZ) or hypertrophic (HZ) zones were also measured. Our other work has indicated that measurements of ossified elements of the cranial base reveal disproportionately more growth of presphenoid (PS) relatively to basisphenoid (BS) in monkeys. But in strepsirrhines, these bones scale similarly to one another when plotted against increasing cranial or midfacial length. When expressed as a ratio of the length of the PZ or HZ to total anteroposterior diameter of the synchondrosis, growth is relatively similar in ISS and SOS among all species studied. However, in anthropoids the length of the PZ in PSept is notably (more than two‐fold) greater than in any other synchondrosis. In strepsirrhines, length of the PZ in PSept is relatively similar to the same zone of other synchondroses. This suggests that the rapid increase in length of the presphenoid in anthropoids is mostly occurring anteriorly, at the midfacial interface. These results, taken at face value, might suggest that anthropoids have a greater magnitude of growth in the septal cartilage compared to strepsirrhines. However, our previous work established that growth at PSept in more multidirectional (radial) than in most other mammals. Instead, our findings emphasize different patterns of sphenoid growth among primates, and offer a tissue‐level explanation for the relatively large PS segment in anthropoid primates. In addition, these findings indicate suggest that growth of the sphenoid is more highly integrated with PS than BS and more interdependent with facial growth in monkeys than in strepsirrhine primates.
Wood B;Mano N;Oladipupo L;Corbin Hayley;Vinyard CJ;DeLeon VB;Smith T
Faseb Journal
2020
2020-04
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1096/fasebj.2020.34.s1.05715" target="_blank" rel="noreferrer noopener">10.1096/fasebj.2020.34.s1.05715</a>