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Morphological study of bovine pregnant corpus luteum cells
1Dept. of Veterinary Anatomy, Rakuno Gakuen University, Hokkaido, Japan.
Insights
Intramitochondrial bodies (IMB) in bovine corpus luteum cells increase with pregnancy. These IMBs appear protein-bound and may be involved in steroid synthesis, unlike other secreted granules.
Area of Science:
- Reproductive biology
- Cell biology
- Biochemistry
Background:
- The corpus luteum is crucial for maintaining pregnancy in bovines.
- Mitochondria within luteal cells play a key role in steroidogenesis.
- Intramitochondrial bodies (IMB) in luteal cells are not well characterized.
Purpose of the Study:
- To morphologically and histochemically characterize intramitochondrial bodies (IMB) in bovine corpus luteum cells.
- To investigate the relationship between IMBs and pregnancy progression.
- To explore the potential role of IMBs and other granules in steroid synthesis.
Main Methods:
- Morphological examination of bovine pregnant corpora lutea.
- Histochemical staining for protein.
- Immunohistochemical analysis using anti-progesterone antibodies.
- Electron microscopy to observe granule morphology and secretion.
Main Results:
- Intramitochondrial bodies (IMB) were observed in large luteal cells (LLC) with sizes ranging from 200-900 nm.
- IMB incidence and diameter increased with advancing pregnancy.
- IMBs reacted positively for protein and progesterone, suggesting a role in steroid metabolism.
- Another type of small, secreted granule reacted with relaxin.
- Small luteal cells (SLC) contained crystalline-like inclusions potentially involved in steroid synthesis.
Conclusions:
- Intramitochondrial bodies (IMB) in bovine LLCs are proteinaceous and progesterone-associated, increasing with pregnancy.
- These IMBs do not appear to be secreted via exocytosis.
- Distinct granules in LLCs and inclusions in SLCs suggest complex roles in bovine corpus luteum function and steroidogenesis.
Abstract:
The bovine pregnant corpus luteum was examined morphologically, to clarify the appearance and properties of the intramitochondrial bodies (IMB) in mitochondria of the large luteum cell (LLC). The incidence and diameter of the IMB (200-900 nm) showed a tendency to increase with the advance of pregnancy. Histochemically, the IMB reacted positively with protein, and immunohistochemically, they reacted IMB with 11 alpha-hydroxyprogesterone-1-11 succinyl-bovine serum albumin (P-BSA). The IMB seemed to combine with protein, and these granules did not undergo exocytosis. The cytoplasm of LLC contained another type of small electron-dense granules that were 150-200 nm in diameter, had an orifice for secretion, and reacted with relaxin. Small luteum cells (SLC) revealed crystalline-like inclusions. It is suggested that these inclusion cells participate in the synthesis of steroids.