类器官培养已广泛用于正常组织重建和疾病建模。然而，建立在稳态条件下模仿体内结构、大小和功能的类器官仍然具有挑战性。在这里，我们描述了一种长期成体干细胞衍生的乳腺迷你培养系统的开发，该系统支持强大的三维生长，概括了正常乳腺的形态、规模、细胞背景和转录异质性。干细胞的自组织能力和产物的稳定性是由细胞外基质、环境信号和动态生理周期的协调组合决定的。我们发现这些微型腺体具有激素反应性，并且可以重现整个产后乳房发育，包括青春期、发情周期、哺乳期和复旧期。我们还观察到，这些微型腺体维持了乳腺干细胞的存在，并且还可以在谱系追踪测定中重现从胚胎双能性到出生后单能性的命运转变。此外，在诱导小腺体中癌基因表达后，我们在小鼠模型中观察到体外和体内肿瘤的发生。总之，这项研究提供了一个实验系统，可以支持动态微型乳腺，用于研究生理相关的复杂生物过程。© 2023。作者，获得 Springer Nature America, Inc. 的独家许可。

Organoid culture has been extensively exploited for normal tissue reconstruction and disease modeling. However, it is still challenging to establish organoids that mimic in vivo-like architecture, size and function under homeostatic conditions. Here we describe the development of a long-term adult stem cell-derived mammary mini gland culture system that supports robust three-dimensional outgrowths recapitulating the morphology, scale, cellular context and transcriptional heterogeneity of the normal mammary gland. The self-organization ability of stem cells and the stability of the outgrowths were determined by a coordinated combination of extracellular matrix, environmental signals and dynamic physiological cycles. We show that these mini glands were hormone responsive and could recapitulate the entire postnatal mammary development including puberty, estrus cycle, lactation and involution. We also observed that these mini glands maintained the presence of mammary stem cells and could also recapitulate the fate transition from embryonic bipotency to postnatal unipotency in lineage tracing assays. In addition, upon induction of oncogene expression in the mini glands, we observed tumor initiation in vitro and in vivo in a mouse model. Together, this study provides an experimental system that can support a dynamic miniature mammary gland for the study of physiologically relevant, complex biological processes.© 2023. The Author(s), under exclusive licence to Springer Nature America, Inc.