Defining "True" Paranasal Sinuses: Histological Indicators of Secondary Pneumatization

最近使用计算机断层扫描（CT）来研究鼻窦，导致了对这些粘膜排列的颅腔的系统发育意义和功能的重新关注。然而，通过CT识别鼻窦是很复杂的，因为即使是没有真正鼻窦的哺乳动物，鼻腔也有凹区（称为隐窝），这可能被误认为是鼻窦。区别在于发展；这些凹陷仅仅是软骨鼻囊骨化的产物，而真正的鼻窦是由一个被称为气化的过程形成的，在这个过程中，骨（可能还有软骨）被特殊细胞（破骨细胞）主动移除。迄今为止，还没有研究记录了这些不同过程的组织学和细胞特征，这些差异导致不同物种之间的颅骨形状非常不同，并且很可能是哺乳动物物种（包括人类）中具有临床重要性的发育异常的基础。在这个项目中，研究人员将确定在非人类灵长类动物中，形成可识别的鼻窦与可比的先天隐窝的空间之间是否存在微观差异。他们将研究有上颌窦和/或额窦和没有上颌窦的灵长类新生动物尸体，比较微观解剖学方面的情况，如羟基磷灰石密度和鼻囊壁组织破坏的模式，以及凹窝和新生窦的骨重塑活动。沿着鼻窦/窝骨边界的骨细胞显微镜检查将揭示骨移除（破骨细胞）和骨沉积（成骨细胞）的活动模式。免疫组织化学方法通过识别骨和破骨细胞前体细胞的结合位点，增加了对破骨细胞活性的更严格审查。本研究验证了鼻窦炎是通过侵入性发育轨迹形成的，与常规骨重塑不同。研究人员的目标是明确区分副鼻窦和隐鼻窦，并更清楚地了解形成“真正”鼻窦的过程——气化。这项研究将有助于研究生的智力发展，他们将有机会在项目的几乎每个阶段提供帮助。从标本中提取的组织学图像的数字档案将被创建并在互联网上提供，为面部解剖和个体发生的其他研究者提供资源。这项研究的结果将作为基础知识，为今后的工作提供信息。这些信息对于任何物种的鼻窦的明确识别都是必要的，这将为比较CT研究和鼻窦病理的临床研究提供更坚实的基础。例如，将这些空间作为重要的系统发育特征和充分理解面部骨骼的某些先天性异常（例如，鼻窦缺失和其他异常）取决于对鼻窦如何形成的清晰理解。

The recent use of computed tomography (CT) to study paranasal sinuses has resulted in a renewed focus on the phylogenetic significance and function of these mucosa-lined cranial cavities. However, identification of sinuses via CT is complicated because even mammals that lack true sinuses have concave regions (termed recesses) of the nasal cavity that can be mistaken for them. The difference is developmental; these recesses are simply the product of ossification of the cartilaginous nasal capsule, while true sinuses develop by a process known as pneumatization in which bone (and possibly cartilage) is actively removed by special cells (osteoclasts). To date, no study has documented the histological and cellular characteristics of these divergent processes, which lead to very different cranial shapes among species, and may well underlie developmental anomalies of clinical importance within mammalian species (including humans). In this project, the researchers will determine if microscopic distinctions exist between spaces that form identifiable paranasal sinuses versus the comparable natal recess in nonhuman primates. They will study cadaveric neonates of primates that do and do not develop maxillary and/or frontal sinuses, comparing such microanatomical aspects as hydroxyapatite density and patterns of tissue break-down in the nasal capsule walls, as well as bone remodelling activity in recesses and nascent sinuses. Microscopic examination of bone cells along the osseous boundaries of the sinuses/recesses will reveal the pattern of activity of bone removal (by osteoclasts) and bone deposition (by osteoblasts). Immunohistochemical methods with add greater scrutiny of osteoclast activity by identifying binding sites on bone as well as osteoclast precursor cells. This research tests the hypothesis that paranasal sinuses form via an invasive developmental trajectory that is distinct from routine bone remodeling.The researchers aim to draw a firm distinction between paranasal sinuses and recesses, and to more clearly understand the process which forms a "true" sinus - pneumatization. This research will contribute to the intellectual development of a graduate student, who will have the opportunity to assist in nearly every phase of the project. A digital archive of histological images from the specimens will be created and made available on the internet, providing a resource for other investigators of facial anatomy and ontogeny. The results of this research will serve as foundational knowledge to inform future work. Such information is needed to allow unambiguous identification of sinuses in any species, which will provide a firmer foundation for comparative CT studies and clinical research into sinus pathology. For example, the use of these spaces as phylogenetically important traits and the full understanding of certain congenital abnormalities of the facial skeleton (e.g., sinus absence and other abnormalities) hinge on a clear understanding of how sinuses form.