## Corpus Luteum: Histology and Function ### Structure and Composition The corpus luteum is a temporary endocrine gland formed after ovulation from the remnants of the ovulated follicle. **Key Point:** The defining histological feature of the **functional corpus luteum** is the presence of **large, lipid-rich steroid-secreting cells** (luteal cells) with abundant mitochondria and smooth endoplasmic reticulum (SER). ### Histological Features of Active Corpus Luteum | Feature | Description | Function | |---------|-------------|----------| | **Luteal cells** | Large (20–30 μm), polygonal, lipid-rich | Progesterone and estrogen secretion | | **Mitochondria** | Abundant, with tubular cristae | ATP production for steroidogenesis | | **Smooth ER** | Extensive network | Cholesterol uptake and steroid synthesis | | **Lipid droplets** | Numerous, golden-yellow | Cholesterol substrate storage | | **Vascularity** | Rich capillary network | Nutrient and hormone transport | ### Comparison: Corpus Luteum vs. Corpus Albicans | Feature | Corpus Luteum (Days 8–14 post-ovulation) | Corpus Albicans (After regression) | |---------|------------------------------------------|-----------------------------------| | **Cell type** | Large, lipid-rich luteal cells | Fibroblasts only | | **Lipid content** | Abundant | None | | **Vascularity** | Rich | Minimal | | **Endocrine function** | Active (progesterone, estrogen) | None | | **Appearance** | Yellow, vascularized | White, fibrous | | **Duration** | 12–14 days | Permanent scar | **High-Yield:** The corpus albicans is simply the **fibrotic scar** left behind after luteal regression. It has no endocrine function and persists as a white fibrous remnant. **Clinical Pearl:** In pregnancy, the corpus luteum persists and continues to secrete progesterone until the placenta takes over (around week 8–10 of gestation). 
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