卵子內空泡成因為smooth endoplasmic reticulum clusters

MII卵子內有空泡，其成因為smooth endoplasmic reticulum clusters

過高之E2可能是其形成原因

MII卵子內有空泡,其形成胚胎品質較差，流產率較高

http://humrep.oxfordjournals.org/content/19/7/1591.abstract?ijkey=fd39c96c2a44b24c217b8a0a4d7c650ebd3aa791&keytype2=tf_ipsecsha

The relationship between pregnancy outcome and smooth endoplasmic reticulum clusters in MII human oocytes

1. J. Otsuki1,2,6, 
2. A. Okada3, 
3. K. Morimoto4, 
4. Y. Nagai1 and 
5. H. Kubo5

+Author Affiliations

1. ¹Nagai Clinic, Misato, Saitama 341‐0004,
2. ²Department of Biological Molecule, Graduate School of Science, Toho University, Funabashi 274‐0072,
3. ³Department of Anatomy, School of Medicine, Toho University, Oomori, Tokyo 143‐0015,
4. ⁴Japan Electron Optics Laboratory DATUM, Akishima, Tokyo 196‐1122 and
5. ⁵Department of Obstetrics and Gynecology, School of Medicine, Toho University, Oomori, Tokyo 143‐0015, Japan

1. 6To whom correspondence should be addressed at: Nagai Clinic, 607‐1 Misato, Saitama 341‐0004 Japan. e‐mail: midori@nagai‐cl.com

• Received September 30, 2003.
• Accepted March 23, 2004.

 

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Abstract

BACKGROUND: During ICSI, we occasionally observe pronucleus sized translucent vacuoles. We investigated why these vacuoles occur and determined the effect on pregnancy outcome. METHODS: Translucent vacuole‐positive oocytes and the corresponding cohort were examined by transmission electron microscopy (TEM) and histochemical staining with DiI and ER‐Tracker. Stimulation methods, hormonal levels, patients’ condition and grade of transferred embryos were compared between vacuole‐positive and vacuole‐negative cycles. RESULTS: By TEM, we confirmed that the vacuoles were tubular‐type smooth endoplasmic reticulum clusters (sERCs). Numerous small sERCs were also observed in the oocytes from the same cohort. Veeck’s grades of transferred embryos were higher in sERC‐positive cycles and fertilization rate was similar to those of sERC‐negative cycles. However, in sERC‐positive cycles, significantly lower pregnancy and higher biochemical pregnancy rates were shown. Serum estradiol levels on the day of hCG administration were significantly higher in sERC‐positive cycles. CONCLUSIONS: The presence of sERCs is associated with lower chances of successful pregnancy, even in sERC‐negative oocytes from the same cohort that are transferred along with the sERC‐positive oocytes. High estradiol levels could be one of the causes of sERC formation.

Figure 1. A pronucleus sized slightly bulged/flat translucent vacuole (arrow) localized in the centre of the cytoplasm at the MII stage (A) and fluid‐filled vacuoles at the MII stage (B).

Figure 2. The translucent vacuoles were smooth endoplasmic reticulum clusters (sERCs). Light microscopic observation of MII stage oocyte with a large translucent vacuole (arrow, A‐a) and its cohort oocyte (B‐a) obtained from the same patient. Transmission electron microscope images of translucent vacuoles (A‐b). A tubular type of large sERCs (***) and a medium‐sized sERC (**) were observed within the cytoplasm. The inset is an enlarged image of a part of a large sERC structure (box). M; mitochondria. A transmission electron microscope image of a cohort oocyte (B‐b). Numerous small sERCs (*), 2–5 µm in diameter, were seen in a cortical area. The large translucent vacuoles were brightly stained by DiI (C) and ER tracker (D).

Figure 3. Appearance and growth of the sERCs in cultured oocytes. The denuded oocytes in which no sERCs had been seen were cultured for 2–5 days. A large sERC appeared after 4 days in the cortical area (A), and three medium sized sERCs appeared after 3 days (B). The light microscopic images (left) and the confocal images stained with DiI (right) are shown. An oocyte in which a medium sized sERC had been observed during the denuding procedure was cultured (C). The time course images of this oocyte are shown. The size of a growing sERC indicated by the arrows was measured during incubation (0–30 h).