Pregnancy and Parturition
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What is pregnancy?
The condition when the female animal develops offspring in the uterus
What is gestation
The period from fertilization to parturition that occurs in four main phases
What are the four phases of gestation?
1.) Fertilization and early embryonic development 2.) Implantation of the embryo to the uterine wall 3.) Placentation/development of the placenta 4.) Fetal growth
Where does the first step of gestation (fertilization and early embryonic development) occur?
Lumen of the female reproductive tract
What does the second step of gestation (implantation of the embryo to the uterine wall) require?
Appropriate development/thickening of the endometrial layer
What does the third step of gestation (placentation, or development of the placenta) involve?
Development of fetal membranes
When do spermatozoa become motile?
After ejaculation
What is the fate of the first arriving spermatozoa?
They typically aren’t the ones to accomplish fertilization
What can result in oxytocin release in natural and artificial insemination?
Tactile stimulation of the female reproductive tract
What is oxytocin release a result of and what does oxytocin do?
It’s released as a result of a neural reflex and it promotes contraction of smooth muscle in the female tubular genitalia to help transport spermatozoa
Nontactile stimuli can release oxytocin from what location?
Posterior pituitary gland
What can release and effects of oxytocin be dampened by?
Stressors that increase sympathetic tone (sympathetic impulses = fight or flight)
What does presence of semen in the female reproductive tract result in?
An immunologic reaction and inflammation
Why is an immunologic reaction present when sperm is in the reproductive tract?
To clear the remaining debris as the sperm become nonviable
What is the timeframe for viability and survival times of spermatozoa under normal conditions?
They are only viable for a matter of hours and are correlated to the period of sexual receptivity of the female
When does insemination most often occur and why?
It most often occurs prior to ovulation so the viable sperm are present when the ova arrive for fertilization
What does the zona pellucida surround?
Vitelline membrane (cell membrane/plasma membrane of the ovum)
What is the number of granulosa cells surrounding the zona pellucida called?
Cumulus oophorous
How many haploid spermatozoa does the male produce for every stem cell?
4
How many mature gametes does the female develop per cycle?
1
What is the genetic material that is discarded during ova maturation called?
Polar body
What is the zona pellucida?
A semipermeable membrane made of glycoproteins
What does the zona pellucida contain?
Receptor sites for attachment of sperm and Zona Protein 3 (ZP3)
What does the sperm do after binding to the zona pellucida?
The acrosome reaction occurs, which releases enzymes that break down the zona pellucida and allow the passage of sperm to the vitelline membrane