Accordi F, Chimenti C
Dipartimento di Biologia Animate e dell'Uomo, Università La Sapienza, Rome, Italy.
J Anat. 2001 Oct;199(Pt 4):419-27. doi: 10.1046/j.1469-7580.2001.19940419.x.
Programmed cell death or apoptosis occurred in anuran amphibian larval pancreas as a remodelling agent, and was responsible for the reduction of the gland volume during metamorphosis. Apoptotic cells were recognisable by their morphological characteristics and could be immunocytochemically detected by means of the TUNEL reaction, which evidenced nuclear DNA fragmentation. During the last stages of prometamorphosis, that is in the period of hindlimb differentiation, only a few TUNEL positive cells occurred, whereas they increased at the beginning of metamorphic climax, that is at forelimb emergence and during tail regression. Under the electron microscope, the typical morphological characteristics of apoptosis were observed: decrease in size, and the presence of wide intercellular spaces and nuclei with dense chromatin masses arranged in crescents. The fragmentation of these cells produced the so-called 'apoptotic bodies': portions of cytoplasm lined by a membrane, containing nuclear fragments and cytoplasmic organites. Dead cell elimination is hypothesised to occur by phagocytic ingestion.
程序性细胞死亡或凋亡作为一种重塑因子发生在无尾两栖类幼体胰腺中，并且是变态发育期间腺体体积减小的原因。凋亡细胞可通过其形态特征识别，并且可以通过TUNEL反应进行免疫细胞化学检测，该反应证明了核DNA片段化。在前变态的最后阶段，即在 hindlimb分化期，只有少数TUNEL阳性细胞出现，而在变态高潮开始时，即在forelimb出现和尾巴退化期间，它们的数量增加。在电子显微镜下，观察到凋亡的典型形态特征：细胞大小减小，细胞间间隙变宽，细胞核中染色质块密集排列成新月形。这些细胞的碎片化产生了所谓的“凋亡小体”：由膜包裹的细胞质部分，包含核碎片和细胞质细胞器。推测死细胞的清除是通过吞噬作用发生的。 （注：hindlimb和forelimb在专业语境中一般分别指后肢和前肢，这里按原文未翻译为中文，以免影响专业准确性，你可根据实际需求调整。）
