Morphometric quantification of mitochondria in the two steroidogenic ovine luteal cell types.

Progesterone secretion is regulated by differentmechanisms in largeand small steroidogenic ovine luteal cells.Large cellssecreteapproximately 7-foldmore progesterone in an unstimulated state than small cells. Since cholesterolside-chaincleavage,which iscatalyzed by an inner mitochondrial membrane enzyme complex, is a major rate-limiting step in progesterone synthesis, mitochondrial components were quantified in the two steroidogeniccelltypes throughout the estrouscycle.Corpora lutea collected on Days 4 (n = 4),8 (n = 4), 12 (n = 5), and 16 (n = 6) of the estrouscyclewere prepared for electron microscopy. Volume densities of cell types within corpora lutea and mitochondrial densities within cell types were estimated by point-counting; nuclear and cytoplasmic volume densities were estimated by planimetric analysis. A total of570 micrographs (magnification 5300 x) were analyzed. Large cell volume density was unchanged during the cycle (35 ± 1%) while small cell volume density increased (pLarge cell mitochondrial volume density increased (p

Keywords:

• Anatomy
• Luteal phase
• Large cell
• Endocrinology
• Estrous cycle
• Internal medicine
• Cytoplasm
• Corpus luteum
• Ovary
• Biology
• Inner mitochondrial membrane
• Mitochondrion
• enzyme complex
• progesterone secretion

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