When the Y chromosome of a Mus musculus domesticus mouse is placed onto the C57BL/6J (B6) inbred genetic background, the XY (B6.Y TIR) progeny develop only ovaries or ovotestes during fetal life. At puberty, while some of the hermaphroditic males become fertile, none of the XY sex-reversed females produce litters. The objective of my study was to clarify the cause of infertility in B6.YTIR females. We have previously demonstrated that the eggs ovulated from B6.YTIR ovaries undergo fertilization efficiently, but cannot develop beyond the 2-cell stage. In the present study, we collected oocytes directly from XY ovaries, and examined their maturation, fertilization and embryonic development in vitro. The results show that the majority of fertilized eggs fail to reach the blastocyst stage. To determine whether developmental incompetence of XY oocytes can be attributed to defects in the oocytes themselves or the surrounding XY somatic cells, we constructed female mouse chimera composed of B6.YTIR and XX BALB/c cells. All chimeric females produced progeny exclusively derived from XX oocytes. For comparison, most of XX ↔ XX chimeric females produced progeny derived from oocytes of either strain. / The ability of XY oocytes to regulate granulosa cell differentiation and functions was assessed in oocyte-cumulus complexes (OCC) in vitro . Microsurgical removal of oocytes prevented cumulus cell expansion and suppressed estradiol production while it promoted progesterone production. Coculture of the oocytectomized OCC with denuded oocytes from either XX or XY ovaries resumed cumulus expansion and the normal endocrine profile. Morphometric analyses indicated that XY oocytes were significantly smaller and their zona pellucida layer thinner than XX oocytes as early as the preantral stage. Furthermore, XY oocytes were attached with fewer cumulus cells in antral follicles. To determine whether developmental incompetence of the zygotes from XY ovaries resides in the nuclear or cytoplasmic component, we exchanged the pronuclei between the zygotes derived from B6.YTIR oocytes and those from XX oocytes and examined their development in vitro. The results indicate that both compartments are defective in the B6.YTIR oocyte. / In conclusion, the XY oocyte becomes cell-autonomously defective in both nuclear and cytoplasmic components during early oogenesis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.34500 |
| Date | January 1997 |
| Creators | Amleh, Asma. |
| Contributors | Taketo, Teruko (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001615653, proquestno: NQ36953, Theses scanned by UMI/ProQuest. |
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