Breeding Behavior, Pregnancy, Maternal Recognition Flashcards
Process of erection
- arterial blood fills sinusoids
- venous outflow is restricted via ischiocavernosis contraction
- pressure builds in corpus cavernosum
- retractor penis muscle relaxes
- erection and protrusion occur
- nitric oxide initiates cascade = erection
Erection is under ________ control
Parasympathetic
Ejaculation
Propulsive discharge of semen from the penis
- stimulation of glans penis
Ejaculation is under _____ control
Sympathetic
Contraction of what muscles leads to ejaculation?
- urethralis
- bulbospongiosus
- ischiocavernosus
What causes retrograde ejaculation?
Where sperm goes into the bladder
- could be an issue with the nervous system
- uncoordination among the muscles
Ram mating
- duration of copulation: 1-2 sec
- volume of ejaculate: .8-1 ml
- semen deposition: external cervix
- # of ejaculations: 10
- max # to exhaustion: 30-40
Bull mating
- duration of copulation: 1-3 sec
- volume of ejaculate: 3-5 ml
- semen deposition: fornix vagina
- # of ejaculations: 20
- max #: 60-80
Stallion mating
- duration of copulation: 20-6 sec
- volume of ejaculate: 75-120 ml
- semen deposition: external cervical os, enters uterus at high pressure
- # of ejaculations: 3
- max #: 20
Boar mating
- duration of copulation: 5-20 min
- volume: 200-250 ml
- semen deposition: cervix/uterus
- # of ejaculations: 3
- max #: 8
Cranial vagina
- bull
- ram
- buck
- dog
- tom
Intra cervical
- boar
Intra uterine
- stallion
- alpaca
Artificial insemination
- intra uterine deposition
What are the 3 stages of sperm transport?
- short, rapid transport (2-10 min)
- colonization of reserviors (cervix and UTJ)
- slow, prolonged release of sperm cells
Fertilization occurs when
A minimum number of sperm cells reach the site of fertilization
Can one sperm make it to the ovary on its own?
No
Influence of estrogen causes the female tract to have
Elevated tone and motility
- prostaglandins in semen have same effect
Rapid phase
Sperm reach oviduct in a few minutes
Sustained phase
Sperm reside at ostium and slowly enter oviduct
- sperm reservoir
Colonization of reservoirs
Huge numbers of sperm are trapped in folds of the cervix
What directs sperm toward the cervical crypts?
Cervical mucus
- under influence of estrogen
Reservoir is located at the uterine-tubular junction for species that ejaculate into _______
Uterine horns
Fate of sperm cells
Almost all sperm cells are lost from the tract shortly after breeding
- 60% are lost after AI
- 0.007% of sperm cells reach site of fertilization
_______ remove many sperm cells after breeding
Neutrophils
Capacitation
Final maturation process which allows sperm to fertilize the ovum
- occurs in female repro tract (specific site varies)
- physiological and biochemical
- is reversible
Sperm must undergo changes that are required, prior to
Penetration of the ovum
- phospholipid bilayer is altered, permitting acrosome reaction to occur
Seminal plasma
Coats sperm with proteins that are stripped away when in the female tract
- sperm is coated prior to ejaculation
- allows sperm to bind to the zona
Capacitation prevents
Premature acrosome activation until sperm are at the site of fertilization
What products can induce capacitation?
Heparin
Seminal plasma contains a ________
Decapacitation factor
Acrosome reaction
Occurs in presence of oocyte
- orderly fusion of sperms’ plasma membrane and outer acrosomal membrane
Acrosome reaction allows sperm to
Penetrate and digest its way thru the zona of the oocyte
- exposes equatorial segment for later fusion with plasma membrane of oocyte
Acrosome reaction tests
Documents efficiency
What are the 2 prerequisites for oocyte penetration?
- capacitation
- acrosome reaction
Oocyte is activated by
Fusion with the sperm
- meiosis that was arreted in metaphase 2 is resumed
- cortical granules are released, mediating polyspermy prevention
Polyploid nucleus
Fertilization of oocyte by more than one sperm
= death
Zona block
Zona undergoes biochemical changes that prevent other sperm from penetrating the zona
- first mechanism to prevent polyspermy
Vitelline block
Prevents oocyte plasma membrane from fusing with more sperm
- 2nd mechanism to prevent polyspermy
Syngamy
Fusion of male and female pronuclei at time of fertilization
Embryo
Organism in early stages of development
- cannot be distinguished
Fetus
Developing offspring that is still within the uterus
- recognizable as a specific specie
Early embrogenesis occurs in the
Oviduct
How do medications prevent pregnancy?
Delay movement of embryo
An oocyte after fertilization is called a
Ootid –> zygote –> 2 celled stage –> 4 cell –> 8 cell –> morula –> crosses UTJ –> early blastocyst –> hatching blastocyst –> hatched blastocyst
_____ must be prevented for early embryo to survive
Luteolysis
- destruction of the corpus luteum
High ____ levels must be maintained to maintain pregnancy
Progesterone
How does the conceptus prevent luteolysis?
Signals its presence in the uterus
- if signal is inadequate or mistimed, MRP will not occur and luteolysis will occur
If no embryo is present _____
No maternal recognition factor –> oxytocin is released from CL –> binds oxytocin receptors on endometrium and stimulates PGF2a release = corpus luteum is lysed and a new cycle begins
Process in the ewe, doe, and cow
Blastocyst produces interferon tau from day 13-21 after ovulation –> IFN-tau binds to endometrium and inhibits oxytocin receptor synthesis –> pregnancy is maintained
PGF2a production is dependent on
Threshold number of oxytocin receptors being present
Process in the sow
Conceptus produces estradiol as signal for MRP –> E2 is produced at day 11 –> PGF2a is rerouted toward uterine lumen –> luminal PGF2a has no access to circulation, preventing luteolysis
A sow must have _____ in each horn for pregnancy to be maintained
2 conceptuses
Process in the mare
Presence of conceptus between days 12-14 prevents luteolysis
- conceptus must migrate often to signal presence (is spherical, just rolls around)
Process in dog and cat
Obligatory diestrus period after ovulation that lasts as long/longer than gestation
- CL of pregnancy and CL of normal cycle have similar lengths
- P4 has no use as a pregnancy test in dogs/cats
