卵子極體與meiotic spindle角度過大施行ICSI後預後不佳

以Polscope觀察，
卵子第一 極體(1st PB) 與 meiotic spindle 角度過大(>90度)
卵子施行ICSI後預後不佳




http://humrep.oxfordjournals.org/content/18/6/1289.full

Relationship between meiotic spindle location with regard to the polar body position and oocyte developmental potential after ICSI

1. L. Rienzi1,3, 
2. F. Ubaldi1, 
3. F. Martinez1, 
4. M. Iacobelli1, 
5. M.G. Minasi1,
6. S. Ferrero1, 
7. J. Tesarik2 and 
8. E. Greco1

+Author Affiliations

1. ¹Centre for Reproductive Medicine, European Hospital, Rome, Italy and
2. ²MAR&Gen, Molecular Assisted Reproduction & Genetics, Granada, Spain

1. 3To whom correspondence should be addressed at: Centre for Reproductive Medicine, European Hospital, Via Portuense 700, 00149 Rome, Italy. e‐mail: rienzi.laura@libero.it

• Received January 17, 2003.
• Accepted March 12, 2003.

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Abstract

BACKGROUND: The recent development of a computer‐assisted polarization microscopy system (Polscope) with which the meiotic spindle can be visualized in living oocytes on the basis of its birefringence permits analysis of the meiotic spindles of oocytes subjected to ICSI. Previous studies have shown that the meiotic spindle is not always aligned with the first polar body (PB) in metaphase II human oocytes prepared for ICSI. In the present study, the relationship between the degree of meiotic spindle deviation from the first PB location and ICSI outcome was analysed. METHODS: Oocytes were divided into four groups according to the angle of meiotic spindle deviation from the PB position. The angle of deviation was 0–5°, 6–45°, 46–90° and >90° for groups I to IV respectively. RESULTS: The rates of normal [2 pronuclei (PN)] and abnormal (1PN or >2PN) fertilization did not differ between groups I, II and III. However, the rate of normal fertilization was lower among oocytes in which the meiotic spindle deviation angle was >90°; this led to an increased proportion of tripronucleated zygotes that failed to extrude the second PB. When embryos developed from normally fertilized oocytes were evaluated on day 3 after ICSI, no relationship was found between the angle of meiotic spindle deviation and embryo quality. The meiotic spindle was not detected in only 9% of oocytes, and these showed a higher incidence of fertilization and cleavage abnormalities than did oocytes in which the spindle was detected. When oocytes at metaphase I after cumulus oophorus and corona radiata removal were matured in vitro, the meiotic spindle was detected in 53.8% of those that reached metaphase II. In these in‐vitro‐matured oocytes the meiotic spindle was always aligned with the first PB, suggesting that misalignment seen in those oocytes matured in vivo resulted from PB displacement during manipulations for cumulus and corona removal. CONCLUSION: High degrees of misalignment between the meiotic spindle and the first PB predict an increased risk of fertilization abnormalities. However, when normal fertilization had occurred, the cleavage potential of embryos developing from such oocytes was not impaired. These findings facilitate the selection of oocytes for ICSI in situations when the creation of supernumerary embryos is to be avoided.

Figure 1. Schematic representation (upper) and representative micrographs (lower) of metaphase II oocytes showing different angles of deviation of the meiotic spindle, visualized using the Polscope system, with regard to the location of the first polar body (in the 6 o’clock position). These angles, measured between the line connecting the oocyte centre with the meiotic spindle and that connecting the oocyte centre with the first polar body are 0° in panel I, 6° in panel II, 85° in panel III, and 110° in panel IV. These images represent the four oocyte groups (spindle deviation angles of 0–5°, 6–45°, 46–90° and >90° respectively) that were compared as to the fertilization outcomes and the quality of embryos developing from normally fertilized oocytes. The range of the deviation angles characterizing each of the four groups is shown in the upper panel.

Table I.

Relationship between the angle of spindle deviation with regard to the first polar body at the time of ICSI and the percentages of in‐vivo‐matured metaphase II oocytes developing 1, 2 and >2 pronuclei (PN)

Deviation angle	Oocytes (%)
	n	1PN	2PN	>2PN
0–5°	254	12 (4.7)	188 (74.0)a	8 (3.1)e
6–45°	104	6 (5.8)	78 (75.0)b	4 (3.8)f
46–90°	102	2 (2.0)	84 (82.3)c	2 (2.0)g
>90°	24	2 (8.3)	12 (50.0)d	4 (16.7)h