16 Questions
What is the primary function of the removal of membrane proteins during capacitation?
To aid in the penetration of the oocyte
What is the term for the condition where multiple sperm fuse with the oocyte?
Polyspermy
During which stage of fertilization does the sperm lose its tail?
Fusion with the oocyte plasma membrane
What is the resulting product of the fusion of sperm with the oocyte?
Diploid zygote
What is the primary characteristic of the cell divisions during cleavage?
Rapid mitotic divisions
Where does the process of capacitation occur?
Cervical mucus
What is the purpose of the corona radiata and zona pellucida?
To block sperm penetration
What is the stage of fertilization that occurs immediately after sperm deposition in the vagina?
Waiting period for capacitation
What is the main purpose of the abundant cytoplasm in the conceptus during pre-embryonic cleavages?
To allow for rapid cell division without changing the total volume
What would happen to the endometrium if the implanted blastocyst did not secrete human chorionic gonadotropin (hCG)?
It would slough off during the process of menses
What is the primary function of the syncytiotrophoblast cells during implantation?
To invade and digest the endometrium
What is the main benefit of a small surface area-to-volume ratio for the zygote?
It is beneficial for the zygote to conserve nutrients and energy
What is the typical duration of the implantation process?
About a week
What structures are formed as the pre-embryo floats to the uterus?
The blastocyst and the inner cell mass
What is the role of the LH-like hormone human chorionic gonadotropin (hCG) during implantation?
It maintains the integrity of the corpus luteum
How does the blastocyst obtain nutrients during its journey to the uterus?
It absorbs nutrients from the uterine secretions
Study Notes
Fertilization
- Fertilization is the process of forming a fertilized egg, resulting from sperm deposition in the vagina during copulation.
- Sperm must undergo capacitation, a gradual process of membrane protein removal and release, to penetrate the egg.
- Capacitation occurs as sperm travel through cervical mucus, uterus, and uterine tubes, enabling them to penetrate the oocyte.
- Hundreds of capacitated sperm must break through the corona radiata and zona pellucida to fuse with the oocyte plasma membrane.
- Once fused, the sperm loses its tail and migrates to the center of the oocyte, completing meiosis II and forming a diploid zygote.
Cleavage
- Cleavage is the process of rapid mitotic divisions in the zygote, occurring as it travels down the uterine tube towards the uterus.
- Cell growth periods between divisions are very short, resulting in smaller daughter cells.
- Pre-embryonic cleavages utilize the abundant cytoplasm of the conceptus, dividing rapidly without changing the total volume.
- A small surface area-to-volume ratio is beneficial to the zygote, allowing for efficient diffusion of nutrients and waste.
Implantation
- Implantation begins around day 6-7 after ovulation, as the blastocyst floats to the uterine cavity.
- The endometrium's special glycoproteins aid in blastocyst implantation, and the trophoblast cells attach to the endometrium.
- Syncytiotrophoblast cells invade and digest the endometrium, covering and sealing off the implanted blastocyst within a short time.
- Implantation takes about a week and is completed by the 14th day after ovulation, maintained by human chorionic gonadotropin (hCG) secreted by the trophoblast cells.
Learn about the process of fertilization, where sperm fuses with the egg, resulting in a fertilized egg. Understand the journey of sperm through the cervical mucus, uterus, and uterine tubes.
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