Abstract:
Blow flies (Diptera: Calliphoridae) are generally early colonisers of fresh cadavers, enabling the estimation of a minimum post-mortem interval (minPMI) based on an accurate aging of the oldest immature stages associated with a cadaver. In blow flies, the pupal stage and the subsequent development of the adult take place inside a protective case, the puparium, formed from the hardened and darkened cuticle of the third instar larva. Because the puparium is an opaque structure that shows virtually no external changes, qualitative analyses of the internal tissues can be very informative for determining reliable age-specific morphological markers. Those analyses can be performed using either non-invasive but expensive and not widely accessible techniques, or traditional histological methods, which are invasive as they require the serial sectioning of the sample. Histological methods are often readily available for forensic researchers and practitioners; however, the histological study of blow fly intra-puparial stages has traditionally been hampered by the poor paraffin infiltration of tissues due to the abundance of fat bodies, resulting in usually fragmented sections and the subsequent loss of relevant information. We present here an effective method for the preparation of histological sections of blow fly intra-puparial stages, maximising the paraffin infiltration while enabling the production of clean and entire sections that allow for the use of reliable age-specific morphological markers, thus improving the accuracy of minPMI estimations when access to more costly techniques is not feasible.
摘要:
苍蝇(双翅目:Calliphoridae)通常是新鲜尸体的早期殖民地,能够基于与尸体相关的最老未成熟阶段的准确老化来估计最小验尸间隔(minPMI)。在打击苍蝇,p的阶段和随后的发展的成年人发生在一个保护的情况下,脓疱,由第三龄幼虫的硬化和变暗的角质层形成。因为阴部是一个不透明的结构,几乎没有外部变化,内部组织的定性分析对于确定可靠的年龄特异性形态标记可以提供非常多的信息。这些分析可以使用非侵入性但昂贵且不可广泛使用的技术进行。或者传统的组织学方法,它们是侵入性的,因为它们需要样品的连续切片。组织学方法通常很容易为法医研究人员和从业人员提供;然而,传统上,由于脂肪体的丰富,组织的石蜡浸润不良,阻碍了对腹内阶段的组织学研究,导致通常是零散的部分以及随后的相关信息丢失。我们在这里提出了一种有效的方法,用于制备飞蝇内阶段的组织学切片,最大限度地提高石蜡的渗透,同时能够生产清洁和完整的切片,允许使用可靠的年龄特异性形态学标记,因此,当使用更昂贵的技术不可行时,提高了minPMI估计的准确性。