# 退化（Involution）

- 器官 / 系统：胸腺 / 免疫系统（thymus / immune-system）
- NTP 数据编号：ntp-0028
- 规范 URL：https://www.labsmart.cn/ntp/thymus-involution.html
- 中文图谱总页锚点：https://www.labsmart.cn/ntp-atlas.html#thymus-involution
- 原始出处：https://ntp.niehs.nih.gov/atlas/nnl/immune-system/thymus/Involution
- 授权：美国联邦政府作品，公有领域；引用请标注 NTP Nonneoplastic Lesion Atlas
- 适用说明：仅供科研使用，不用于临床诊断

## 一句话结论
胸腺退化（involution）是一种逐渐发生、不可逆的改变，可能与衰老过程中发生的性类固醇变化有关。

## 病变描述（中文）
胸腺退化（involution）是一种逐渐发生、不可逆的改变，可能与衰老过程中发生的性类固醇变化有关。它是啮齿类动物与年龄相关的正常生理性改变，在慢性生物试验中常见。胸腺退化的典型改变包括皮质淋巴细胞减少、胸腺小叶皱缩、皮质变薄且不规则、皮髓质交界模糊、被膜和小梁脂肪细胞浸润、髓质上皮细胞突出度增加和/或增生、滤泡样B细胞聚集形成、囊肿形成以及浆细胞增生。如有可能，应将退化与原发性或继发性治疗相关萎缩区分开来。与退化相似，胸腺萎缩的特征是继发于胸腺淋巴细胞耗竭的胸腺体积和重量减小。然而，胸腺萎缩与年龄无关，通常由毒性损伤引起，并且在去除诱因后可能可逆。

## 诊断与分级建议（NTP 共识，中文）
胸腺退化不予诊断。如有可能，应将慢性生物试验中常见的正常生理性年龄相关退化与原发性或继发性治疗相关萎缩区分开来（见胸腺-萎缩）。相关链接：胸腺-萎缩

## 英文原文 · Comment
Involution of the thymus is a gradual, nonreversible change, likely associated with sex steroid changes that occur during aging. It is a normal physiologic age-related change in rodents and is commonly seen in chronic bioassays. Changes typical of thymus involution include decreased cortical lymphocytes, shrinkage of thymic lobules, thinning and irregularity of the cortex, blurring of the corticomedullary junction, adipocyte infiltration of capsule and septae, increased prominence and/or hyperplasia of medullary epithelial cells, formation of follicular-like B-cell aggregates, cyst formation, and plasma cell hyperplasia. If possible, involution should be distinguished from primary or secondary treatment-related atrophy. Similar to involution, atrophy of the thymus is characterized by reduced thymus size and weight secondary to thymic lymphocyte depletion. However, atrophy in the thymus is unrelated to age, generally caused by toxic insult, and potentially reversible with removal of the inciting agent.

## 英文原文 · Recommendation
Involution of the thymus is not diagnosed. If possible, normal physiologic age-related involution, which is commonly seen in chronic bioassays, should be distinguished from primary or secondary treatment-related atrophy (see Thymus - Atrophy ). Related Links: Thymus - Atrophy

## 配图
- https://www.labsmart.cn/ntp-atlas-images/ntp_0467.jpg
- https://www.labsmart.cn/ntp-atlas-images/ntp_0464.jpg

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