鳜仔稚鱼骨骼系统骨化发育

采用软骨―硬骨双染色技术,描述了鳜(Siniperca chuatsi)仔稚鱼(1～35日龄)头骨、脊柱、附肢骨骼的骨化发育特征。结果显示:(1)头骨前鳃盖骨于14日龄最先骨化, 15日龄上下颌骨骨化,且上下颌骨相对长度呈现连续变化过程。17日龄后,颌齿、关节骨、舌颌骨骨化;19日龄,隅骨、间鳃盖骨、鳃盖骨、鳃条骨、额骨骨化。20日龄后,方骨、下鳃盖骨、辅上颌骨等骨化; 35日龄,头骨骨化基本完成。(2)脊柱于15日龄由前向后骨化, 20日龄背肋与腹肋由基部向末端骨化, 29日龄骨化完成。脉弓与脉棘、髓弓与髓棘均由前向后、由基部向末端骨化,脉棘与髓棘骨化时间晚于相应的椎体。(3)附肢骨骼骨化顺序依次为胸鳍、背鳍、臀鳍、腹鳍、尾鳍。胸鳍匙骨于16日龄骨化,乌喙骨与肩胛骨于25日龄骨化;背鳍、臀鳍分别于18日龄、20日龄骨化,骨化方式相似;腹鳍于23日龄骨化,骨化方式与胸鳍相反;尾杆骨、尾下骨于25日龄骨化,附肢骨骼于35日龄基本骨化完成。结果表明,鳜骨骼骨化发育与其早期运动、摄食与御敌等行为密切相关。     

合作猪头骨发育研究

以9头不同月龄的合作猪猪头为试验材料,运用大体解剖学的方法对猪头进行处理,测定了不同月龄合作猪头骨相关的基本量度指标、较大头骨的面积以及其牙齿齿式。结果表明,合作猪头骨基本量度指标及较大头骨面积在6月龄～18月龄期间均呈增长趋势,不同月龄齿式与普通家猪的相同。     

西藏马鹿亚种头骨的形态学观察

通过大体解剖学和动物学头骨测定的方法对马鹿头骨进行观察,并与牛、羊、马、鬣羚相比较。雄性马鹿头骨呈狭长的角锥性,额骨上有角突,角突长而分叉；鼻骨较短前窄后宽,前端呈水平状,边缘呈锯齿状,这与马、鬣羚鼻骨不相似；上颌骨接近颌前骨部位有一个犬齿齿槽,齿槽部位有6个臼齿齿槽,下颌骨有6.5个,因此上颌骨臼齿齿列比下颌骨臼齿齿列短；颧骨的前下方、鼻骨的侧面、泪骨的前上方及上颌骨的后上方,形成一个等边三角形缝隙；缝隙与鼻腔之间由一形状不规则的薄骨片隔开,这与牛、羊、马、鬣羚都不相似。     

A histological evaluation of facial suture lines in six horses aged 1 day to 9 years

Craniofacial sutures are fibrous connections between the flat bones in the skull, allowing a small amount of movement to absorb strain and load as long as they are patent. In the present study, we examined the histological appearance of facial suture lines in horses of different ages. The internasal, nasofrontal and maxillolacrimal sutures were macroscopically identified and extracted from the skulls of six horses aged 1 day (two horses), 5 days, 2, 6 and 9 years and prepared into histological samples. The suture lines were then examined for width, form, cell density and morphology, vascularisation and morphology of the surrounding tissue and compared based on the age of the horse. Although macroscopically the sutures became difficult to identify in the 6- and 9-year-old horses, histologically they were clearly visible in all samples, indicating that the sutures were patent and consisted of connective tissue in all analysed horses. The sutures became subjectively narrower with lower cell density in older horses as compared to young horses, and there was a noticeable maturation from woven to cancellous bone surrounding the sutures. Vascular structures were present in all sutures regardless of age or location. In conclusion, this study raises awareness of the histological suture conformation in neonatal and adult horses and their persistence into adulthood. A better understanding of the histological structure of facial sutures and their continued patency into adulthood can aide in the interpretation of radiographs and computed tomography images of the head and in improving treatment methods and outcomes for horses affected with suture exostosis. In addition, if biopsies are taken, clinicians will have a basis on which to determine which cells are related to the disease process and which are normally occurring.     

Host evolution in Mastomys natalensis (Rodentia: Muridae): An integrative approach using geometric morphometrics and genetics

The commensal rodent Mastomys natalensis is the natural reservoir of Lassa arenavirus (LASV), which causes hemorrhagic fever in West Africa. To study a possible effect of the virus on phenotypic and genotypic variation of its persistently infected host, we compared LASV‐positive and non‐infected wild‐caught M. natalensis. The LASV effects on the phenotypic variation were explored using standard external morphometric measurements, geometric morphometric analyses of the cranial size and shape, and brain case volume. The genetic variability of M. natalensis specimens was assessed using 9 polymorphic microsatellite markers. Independent of sex and age, LASV‐infected animals had smaller external body measurements, reproductive organs, skull size and brain case volume. Cranial shape differences between the 2 groups are represented by a lateral constriction of the entire skull. The genetic variability revealed consanguinity only among the LASV‐positive rodents. We hypothesize that growth impairment may result in a selective disadvantage for LASV‐infected M. natalensis, leading to a preferably commensal lifestyle in areas where the LAVS is endemic and, thereby, increasing the risk of LASV transmission to humans.     

COMPUTED TOMOGRAPHIC APPEARANCE OF A NORMAL VARIANT OF THE CANINE TENTORIUM CEREBELLI OSSEUM

A nine-year-old German Shepherd dog presented to the Veterinary Teaching Hospital at North Carolina State University with an eleven-day history of progressive depression, lethargy, inability to walk, blindness and intermittent vomiting. Computed tomography (CT) of the brain was unremarkable; however, bilateral regions of low photon absorption were noted within the tentorium cerebelli osseum. Mean CT numbers of −47.9 Hounsfield units (HU) and −26.4 HU were recorded within the left and right areas, respectively. These areas most likely represent diploë and are presumably a normal variant of the canine skull. A possible explanation for this finding includes a developmental variant where the medial and lateral plates of the tentorium cerebelli osseum fail to fuse, thus leaving a space for diploë accumulation. Use of various combinations of CT windows and numbers can be valuable for characterizing such variants.     

COMPUTED TOMOGRAPHIC CHARACTERISTICS OF MULTILOBULAR TUMOR OF BONE INVOLVING THE CRANIUM IN 7 DOGS AND ZYGOMATIC ARCH IN 2 DOGS

Computed tomography (CT) images of nine dogs with a multilobular tumor of bone of the head were reviewed. The CT characteristics of the neoplasms involving the calvarium (n = 7) were rounded, well defined with a fine granular, nonhomogeneous bone opacity usually in the occipital region. Cranial vault invasion (5 of 7) was commonly found with a significant portion of the mass within the vault. The neoplasms involving the zygomatic arch (n = 2) were also generally rounded and well defined but with a more coarse granular appearance. The common CT findings were best seen when the images were viewed in a bone window.