Gamete Transport And Fertilization Flashcards
It re-absorbs a significant amount of rete fluid into the lumen of epididymal duct
Proximal head of the epididymis
It secretes fluid into the lumen of the epididymal duct
Distal head of epididymis
It lies parallel to the ductus deferens, wherein concentrations of sperm remain relatively constant
Body of epididymis (Corpus)
Sperm within this location are eligible for ejaculation. They move through the DD and into the pelvic urethra during sexual stimulation
Distal Tail (DT) of the Epididymis
Sperm within this location cannot be moved into an ejaculatory position following sexual stimulation.
Proximal tail (PT) of the Epididymis
These are abnormalities that originated during spermatogenesis in the testis.
Primary defects
These are abnormalities that occur during epididymal transport.
Secondary abnormalities
Head abnormalities
Middle-piece abnormalities (e.g., Abaxial attachment, Double / Coiled middle piece, Frayed, thin middle piece)
Tail abnormalities (Coiled-tail)
Primary abnormalities
Loose normal heads
Sperm cells with bent tails
Detachment of galea capitis (acrosome)
Cytoplasmic droplets
Secondary abnormalities
A process of climbing onto the female
Mounting
A successful entrance of the penis into the vagina
Intromission
It takes place in response to sensory stimulation of the glans penis
Ejaculation
Copulatory Behavior Steps
Mounting -> Intromission -> Stimulation of glans penis -> Emission -> Forceful muscle contraction -> Ejaculation / Semen expulsion
An ejaculation phased controlled by Sympathetic NS
Emission
An ejaculation phased controlled by Parasympathetic NS
Expulsion
Sperm is released from epididymis (DT)
Seminal fluid is released from seminal vesicle, prostates, and Cowper’s gland
Sperm and seminal fluid is mixed in prostatic urethra
Emission
Contraction of pelvic muscles
Forceful expulsion of semen through urethral meatus
Expulsion
Peristalsis and beating of cilia in this location brings ovum toward the isthmus
Infundibulum and Ampulla
It has fewer cilia and thicker smooth muscle (dictates movement of ovum)
Isthmus
Ovum transport in the oviduct takes ?
7 days
Via twitching movement, there is fluid flow in these areas
Seminiferous tubules and rete testes
There is smooth muscle contraction and the cilia prevents clogging via swirling motion to separate spermatozoa
Vas efferentia
There is also smooth contraction in these areas
Epididymis, Vas deferens, Pelvic urethra, Penile urethra
It is secreted during copulation and responsible for uterine contractility, sperm transport process, and ejaculatory process
Oxytocin
How long does rapid transport phase take?
15 - 30 minutes
How long does sustained transport phase take?
6 - 12 hours
This occurs via contraction of muscularis layer of the RT during copulation however delivered spermatozoa are not viable
Rapid transport phase
The spermatozoa are transported into oviducts via “trickle-effect” effect, from reservoirs of cervix and UTJ
Sustained transport phase
The UTJ constricts in response to estradiol to restrict sperm passage
Tube-locking
Ejaculate is deposited into where, for these species?
- Humans, Cattle, Sheep, Goats, Dogs, Cats, Rabbits
Cranial Vagina
Ejaculate is deposited into where, for these species?
- Horses, Pigs, Camelids
Cervix / Uterus
Spermatozoa is lost via
Leukocyte phagocytosis
Retrograde transport
Amount of sperm in ejaculate that reach the oviducts after a single mating?
Less than 1%
How do rodents mitigate retrograde loss?
Vaginal plug
How do dogs mitigate retrograde loss?
Copulatory “tie”
How do buck, ram, and rooster mitigate retrograde loss?
High sperm concentration
How do horses and pigs mitigate retrograde loss?
Semen deposited into the uterus
During estrus, secretion of ? from what part of cervical mucosa produces what?
Sulfomucins
Apical portion
Viscous mucus
Less viscous sialomucins are produced in the ?
Basal crypts
Changes undergone by spermatozoa in female genital tract that enables them to penetrate and fertilize an ovum
Sperm Capacitation
Where is the initial site of capacitation if semen is deposited in cranial vagina?
Cervix
Where is the initial site of capacitation if semen is deposited in cervix?
Uterus
Decapacitating factors
Surface molecules (glycoproteins and cholesterol)
Seminal plasma protein coating
Surface molecules (glycoproteins and cholesterol) are secreted from?
Epididymis
Seminal plasma protein coating are secreted by?
Accessory glands:
- Acrosome-stabilizing factors
- Acrosin inhibitors
What removes cholesterol and increases spermatozoa motility?
Sterol acceptors
This is the sperm storage site; much more sperm observed in this site rather than the ?
Isthmus - Ampulla
Result of sperm capacitation
- Increased rate of metabolism
- More rapid beating of flagellum (hyperactivated)
- Plasmalemma protein changes -> allow sperm-egg binding and acrosome-reaction
This induces sperm chemotaxis
Follicular fluid
Duration of sperm residing in cow’s AIJ
1 - 2 hours
Duration of sperm residing in cow’s oviduct
18 - 24 hours
Duration of sperm residing in cow’s uterus
6 - 12 hours
Conditions for fertilization
Normal ovum & sperm
Certain time (12 - 24 hours)
Free / Open RT
Duration of fertilizable life of gametes in most mammals
Sperm (48 hours)
Ovum (24 hours)
Duration of fertilizable life of gametes in bats
Live sperm cells can persist for several months (hibernation)
Duration of fertilizable life of gametes in domestic birds
Fertile sperm lasts for 2 - 15 weeks in Sperm Storage Tubules (SST) in the Utero-Vaginal Junction (UVJ)
A structure adjacent to the surface of ovum plasma membrane
Zona pellucida / Vitelline membrane
Space between the egg membrane and zona pellucida
Perivitelline membrane
Zona pellucida glycoprotein: ZP3
Primary sperm receptor
Zona pellucida glycoprotein: ZP2
Secondary sperm receptor
Zona pellucida glycoprotein: ZP1
Cross-links ZP2 and ZP3
Oocyte Activation
- Polyspermy block
- Reactivation of Meosis II
- Syngamy
- DNA Replication
It is the depolarization of egg membrane during polyspermy block
Fast block
Fast block starts at ?
Fusion of Sperm and Egg Plasma Membranes
Fast block changes membrane potential from ?
- 70mV to + 20mv
Fast block duration ?
Approximately a minute
This is a polyspermy block that’s a cortical reaction and triggered by Ca2++ release from spermatozoa
Slow block
Fusion of cortical granules with egg cell membrane and subsequent release of contents results into?
Zona block
A formation of an impenetrable fertilization envelope/membrane
Zona block
Components of cortical granules
- Peroxidase
- Hydrolase
- Proteinase
- Glycosaminoglycans (GAGs)
Peroxidases hardens the VM protein by?
Cross linking of tyrosine residues
Proteases and hydrolases ?
Trim off receptor proteins
Glycosaminoglycans (GAGs)
Attract water to raise VM
After ovulation, the oocyte is?
Suspended at Metaphase II
What reactivates Meiosis II?
Sperm penetration which triggers Ca2++ release
What then terminates meiosis?
Expulsion of 2nd polar body and formation of a zygote
Where does DNA replication begins?
In each pronuclei after sperm and ovum formation
Combination of two genomes is called?
Syngamy / Amphimixis
What does the sperm contributes to the egg?
Pronucleus and Centriole
This is the successive fertilization of two or more ova from the same ovulation especially different sires
Superfecundation
Superfecundation occurs in what type of animals?
Multiparous animals (e.g., dogs, cats, pigs, some sheep and goat breeds)
