Lecture 7 - Fertilisation and Implantation Flashcards Preview

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Flashcards in Lecture 7 - Fertilisation and Implantation Deck (18):

Semen reaching vagina?

prostatic and seminal vesicle fluid form a coagulation holding ejaculate together and adhering to female reproductive tract


Path of sperm?

cervical mucus typically hostile to sperm movement apart from around the time of ovulation, pre-ovulation it is thin and aligns fibres to allow sperm passage, through uterus for fertilisation at fallopian tube


Estrogen and cervical mucus?

increases volume, clear and watery with high threadability receptive to sperm - mucous contains channels for sperm entry


Progesterone and cervical mucus?

stimulates highly viscous and cross-linked mucous that is a barrier to sperm penetration


Filtering poor sperm?

normal sperm tails cause vibration of mucus, failure to do this may retard progress of poor quality sperm


Sperm transport numbers?

99% dnt reach into cervix (2.5hour life-span in vagina), 48hr in cervixand fallopian, 24 in uterus, 5 day clinical suggestion


Transport time?

up to 7hr to reach ampulla, 30min in uterus, speed related to fertility, speed reduced by ages and freezing, 20scm/hr


Waiting for ovulation?

sperm will travel slower in tubes waiting for ovulation, stored sperm may be released from cervical crypts


Uterian immune response?

leucocytes infiltrate to phagocytose dead or dying sperm



loss of cholesterol from sperm membrane, hyperactivation involving greater movement of head and tail for better movement through tortous folds of fallopian tube, preparation for acrosome reaction


Acrosome reaction?

Ca influx causes fusion of acrosomal and plasma membranes of sperm head fuse, releasing acrosomal contents (hyaluronidase), requires to be near oocyte



oocyte survives 24hr, sperm penetrate layer of cumulus cells surrounding egg (aided by hyaluronidase), encounters and digests corona radiata, reaching zona pellucida through which is perivitelline space -> sperm membrane fuses with oolemmal membrane to enter ovum


Fertilisation proteins?

ZP-1 ZP-2 ZP3 - 3 is primary sperm receptor, binding induces completion of acrosomal reaction


Cortical reaction?

entry of sperm into ovum causes intracellular Ca release, resumes meiosis, cortical granules released into perivitelline space, releasing enzymes that cleave ZP2 and digest ZP3


Resumption of meiosis?

dependant on Ca rise destabilising protein netwokr that held chromosomes in metaphase, are now free to move to poles, second polar body shed


Development prior to implantation?

2 cells in 30hr, blastomeres divide symmetrically, doubling and compacts to become morula at 8-16 cell 72hrs, 60 cell blastocyte at 96hr, 100 cells in 4-5 days when it shouldve reached uterus



trophectoderm (placenta) and inner cell mass (embryo), free floats in uterus 2-3 days before attaching to endometrial epithelium



attachment of blastocytes to endometrial epithelum via specific adhesion molecules