男性原核與2nd極體之相對位置與受精卵分裂有關

2PN(原核)之型態(PN1, PN4)之胚胎發育最佳
PN3之胚胎發育最差
男性PN比女性PN略大
2PN之型態與ICSI精蟲進入之位置無關
2nd PB(極體)比 1st PB為大，完整，較少碎片及顆粒狀細胞質
男性PN與2nd PB之相對位置反應受精卵細胞質內有絲分裂胞器包括紡垂體與PN之相關功能正常與否

http://humrep.oxfordjournals.org/content/19/2/294.full

Developmental potential of human pronuclear zygotes in relation to their pronuclear orientation

1. Suresh Kattera1 and 
2. Christopher Chen

+Author Affiliations

1. Centre for Reproductive Medicine and Gleneagles IVF Centre, Gleneagles Hospital, Singapore 258500

1. 1To whom correspondence should be addressed. e‐mail: suresh.cccrm@pacific.net.sg

• Received July 15, 2003.
• Revision received September 11, 2003.
• Accepted October 9, 2003.

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Abstract

BACKGROUND: Pronuclear zygote morphology has gained much attention recently due to its possible value in predicting implantation and pregnancy. The present study was performed to assess the developmental potential of zygotes with four different pronuclear orientations. METHODS: This prospective study involved 150 IVF and 190 ICSI patients seeking fertility treatment. Pronuclear zygotes were classified for orientation of the pronuclei in relation to the second polar body placed at the 6 o’clock position. Four types of pronuclear (PN) zygote were recognized, namely PN₁, PN₂, PN₃ and PN₄. The main outcome measures were early cleavage rate, quality of embryos, and implantation and pregnancy rates. RESULTS: The most common types of pronuclei orientations were PN₁(31.5%) and PN₂ (29.3%), followed by PN₃ (20.5%) and PN₄ (18.5%). A significantly higher proportion of zygotes with PN₁ and PN₄ types of pronuclear orientation underwent early cleavage and developed into grade I embryos compared with other types (P < 0.0001). There was a tendency for higher implantation and pregnancy rates among patients who received embryos developed from PN₁‐ and PN₄‐type oocytes, but this was not statistically significant. CONCLUSIONS: Zygotes exhibit four types of pronuclear orientation, and this is independent of the fertilizing spermatozoon or its entry point into the oocytes, whether IVF or ICSI is employed. Early cleavage was associated with PN₁‐ and PN₄‐type zygotes, but implantation and pregnancy rates were not associated with pronuclear orientation. Implantation and pregnancy rates tended to be higher for embryos developed from PN₁ and PN₄ pronuclear zygotes. Further studies on a combination of pronuclear orientation and equality of nucleoli may provide a better guide to the implantation potential of embryos.

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Figure 1. Classification of oocytes based on the orientation of pronuclei in relation to second polar body positioned at 6 o’clock.

Table I.

Distribution of pronuclear orientation, equality nucleoli, early cleavage, number of embryos and grade I embryos among the four types of pronuclear zygotes (PN) from ICSI and IVF patients

PN type	No. of zygotes (n = 2714)	Equality of nucleoli	Early cleavage	Total embryos (n)	Grade I embryos
PN1	855 (31.5)	730 (85.3)	579 (67.7)	846	536 (63.2)
PN2	797 (29.3)	407 (51.0)	448 (56.2)	784	433 (55.1)
PN3	558 (20.5)	268 (48.0)	284 (50.8)	549	282 (51.3)
PN4	504 (18.5)	243 (48.2)	322 (63.8)	499	323 (64.7)

Values in parentheses are percentages.

A total of 34 pronuclear zygotes did not cleave.