Gametogenesis And Fertilization Flashcards
During meiosis I, the 46 chromosomes are duplicated into ________ ___________
Sister chromatids
There are 30-40 ___________ during each mejoría I division, allowing for interchange of chromatid segments between homologous chromosomes
Crossovers
Ploidy refers to the number of _________
Chromosome copies
N refers to the number of ________
Chromatid copies
Mitosis results in DIPLOID/HAPLOID 2N/4N cells
Diploid, 2N
Meiosis I begins with HAPLOID/DIPLOID 4N/2N cells
Diploid, 4N
Meiosis I ends with HAPLOID/DIPLOID 2N/1N cells
Haploid, 2N
Meiosis II ends with HAPLOID/DIPLOID 2N/1N cells
Haploid, 1N
In meiosis, the process of chromosomes lining up for crossing over is called ______ and occurs during which phase?
Synapsis, prophase I
Germ cells are formed in the ________ and move to the wall of the yolk sac during week __ then migrate to developing gonads during week ___
Epiblast, 2, 4
Primordial germ cells migrate from around the developing gut tube to the _______ _______
Gonadal ridge
The SRY gene encodes ____ which induces the formation of ________ ________
TDF, seminiferous fords
The X chromosome downregulates _____ while ______ contributed to ovarian differentiation
SF1, Wnt4
It takes ___ days for spermatogonia to develop into mature spermatozoon
74
About how many sperm cells are produced daily?
300 million
Spermiogenesis is the transformation of ______ to ______
Spermatids to spermatozoa
What occurs during spermiogenesis?
Cytoplasm is shed
Formation of neck, middle piece, and tail
Condensation of nucleus
Formation of acrosome
Just prior to ovulation, the 1st/2nd meiotic division is completed
1st
Which hormone surged during ovulation?
LH
Oocyte transport from the fimbria to the ampulla of the uterine tube is aided by what process?
Peristalsis
Oogenesis is not complete until ______
Fertilization
About 7 million oogonia are present at what point in a female’s life?
5th prenatal month
During oogenesis, secondary oocytes are initially formed just prior to ________ with the completion of meiosis I/I
Ovulation, I
What is capacitation?
Removal of glycoprotein coat and seminal proteins from acrosomal membrane
Where does capacitation occur?
Uterine tube
What is the acrosome reaction?
When sperm binds to the ZP3 receptor on the zona pellucida, the breakdown of the acrosomal membrane releases enzymes that digest a path through the ZP
1st stage of fertilization
Penetration of the corona radiata, aided by hyaluronidase, acrosin, and tubal enzymes
2nd stage of fertilization
Penetration of the ZP
- cortical rxn: release of cortical granules within oocyte membrane
- zonal rxn: cortical granules alter zonal proteins, making ZP impermeable to other sperm
3rd stage of fertilization
Fusion of oocyte and sperm membranes
Two components of the cortical reaction
Fast block: Na influx triggered by ZP3 binding changes membrane potential
Slow block: ZP3 binding activates G protein cascade that raises intracellular pH
4th stage of fertilization
Completion of meiosis II and formation of female pronucleus
5th stage of fertilization
Formation of male pronucleus
6th stage of fertilization
Formation of zygote (fusing of pronuclei)
Fertilization stimulates the secondary oocyte to complete _____ meiotic division
2nd
The secondary oocyte is halted in which phase until fertilization?
Metaphase II
Zygote Week 1 events
1-2: blastomere, compaction
3: morula
4: blastocyst (trophoblast + embryoblast)
5: hatching (degeneration of ZP)
Implantation of zygote normally occurs in the ______ wall of the uterus
Superior, posterior
Totipotentiality
Could be anything
Ex. Blastomere
Pluripotentiality
Can be any embryonic cell but not trophoblast cell
Ex. Embryoblast
Multipotentiality
Commutes to becoming cells that have a particular function
Describe the start of implantation
The syncitiotrophoblast invades the endometrium via enzymatic erosion. Hypoblast forms under embryoblast
Describe day 8 of implantation
Amniotic cavity develops
Embryoblast becomes hypoblast and epiblast
Trophoblast becomes cytotrophoblast and syncitiotrophoblast
Describe day 9 of implantation
Amnioblasts line amniotic cavity
Hypoblast cells form membrane called exocoelomic (Heuser’s) membrane
Blastocyst cavity = exocoelomic cavity
What happens on day 11-12 post-fertilization?
Formation of chorionic cavity
What happens on day 13 post-fertilization?
Extraembryonic mesoderm differentiates into somatic mesoderm and splanchnic mesoderm
What happens on day 14 post-fertilization?
Localized area of hypoblast cells become columnar, this prechordal plate is an organizer of the head region
If sperm count/motility is too poor for IUI or IVF, what can be done?
Intracytoplasmic sperm injection
If there is no sperm in the ejaculate, what can be done?
Testicular sperm extraction
