Sperm in the Female Tract Flashcards
What is semen?
A liquid cellular suspension containing spermatozoa and a fluid portion (seminal plasma) contributed by the secretions from the accessory organs of the male reproductive tract
What is seminal plasma and what are its functions?
A nutritive-protective medium for spermatozoa. Components are important for sperm metabolism, function, survival, and transport in the female reproductive tract
What are the characteristics of semen ejaculate in the bull?
Concentrated semen; single fraction
What are the characteristics of semen ejaculate in the stallion?
Ejaculates in a series of “jets”; sperm-rich fraction is ejaculated first in 3-4 high-pressure squirts; last 5 to 8 jets are of lower pressure and contain fewer sperm and are mostly highly viscous seminal plasma
What are the characteristics of semen ejaculate in the boar?
Semen flows from the cervix into the uterine lumen; first fraction is accessory fluids and coagulum; second fraction is the sperm-rich fraction; final fraction is gelatinous coagulum
What are the characteristics of semen ejaculate in the dog?
First fraction is the pre-sperm fraction from prostate; second fraction is sperm-rich (delivered during first stage of coitus); final fraction is from the prostate and ejaculated in surges (second stage of coitus); the “tie” forces the semen into the uterus
What are the biophysical cues that regulate sperm motility in the female tract?
fluid flow, fluid viscoelasticity, wall architecture, and temperature gradients
What are the biochemical cues that regulate sperm motility in the female tract?
chemoattractant; molecular triggers that change sperm flagellar beating pattern; sperm receptors on the epithelium of the tract, which anchor sperm
Describe the difference in swimming pattern of sperm in different mediums.
Sperm swim individually in standard and viscous medium. In viscoelastic medium, sperm swim collectively and form clusters.
How is sperm motility affected by wall and microgroove structures?
Sperm that approach a sidewall from all angles swim along the sidewall. When sperm encounter a microgroove structure, most of them remain in the groove.
What is the first phase of transport of spermatozoa?
Short, rapid sperm transport: within a few minutes after copulation, sperm can be found in the oviducts; functional importance is not known because spermatozoa transported through this rapid route are not viable; might be facilitated by sperm motility as well as a burst of transport activity due to increased muscular contractility.
What is the second phase of transport of spermatozoa?
Colonization of sperm reservoirs
What are the three types of sperm reservoirs?
- Cervical reservoir: complex mucosal folds of cervical crypts trap a massive number of spermatozoa; there are less leukocytes in cervical secretions compared to the vagina or uterus; important for species in which ejaculation occurs in the cranial vagina (cow, sheep, primates)
- Endometrial glands: spermatozoa will enter the glands and may never be released (dog)
- Utero-tubal junction: important for species in which ejaculation occurs in the uterus (pig, horse)
What is the third phase of transport of spermatozoa?
Slow, prolonged release: the spermatozoa from selective reservoirs within the tract for movement towards the site of fertilization; “trickle-like” effect from reservoirs in the cervix and utero-tubal junction; factors include smooth muscle contractions, sperm motility, cervical mucus characteristics, ciliary action, and fluid currents.
What is the sequence of events following the deposition of spermatozoa in the female tract?
1) Immediate transport (retrograde loss, phagocytosis, entrance into cervix/uterus)
2) Cervix: “privileged” pathways, removal of non-motile sperm, removal of some abnormalities
3) Uterus: capacitation initiated, phagocytosis
4) Oviduct: capacitation completed, hyperactive motility
5) Fertilization: acrosome reaction, spermatozoon penetrates oocyte, male and female pronuclei form
What is the fate of spermatozoa in the vaginal environment?
Only in species in which semen is deposited in the cranial vagina (cow, sheep, primates); the vaginal pH is <5, which is inhospitable; but within 8 seconds from the introduction of semen, the pH of the vagina is raised to 7.2 (favorable for sperm motility); coagulation of the semen may play a role in keeping sperm near the cervical os (humans)
What is retrograde loss of spermatozoa?
Spermatozoa that are transported caudally from the site of semen deposition in the female reproductive tract. Minimization of spermatozoa loss depends on physical nature of the ejaculate (concentrated semen, delivery of different fractions, formation of coagulum, and vaginal plug) and site of seminal deposition (vagina vs cervix vs uterus)
What phagocytizes sperm?
Leukocytes
What are the functions of the cervix and its secretion?
Receptive to sperm penetration at or near ovulation, and inhibits migration at other phases of the cycle; acts as a sperm reservoir; protects sperm from the hostile environment of the vagina and from phagocytosis; provides sperm with energy requirements; filters defective and immobile sperm; participates in the capacitation of sperm
Describe cervical mucus and its spinnbarkeit and the fern pattern.
Cervical mucus has rheological properties such as viscosity, flow elasticity, spinnbarkeit, thixotropy, and tack (stickiness); quality and quantity vary depending on the hormonal status of the estrous cycle. Spinnbarkeit is the stretchability, or formation of a thread by the mucus; highest around the ovulation period. The fern (crystallization) pattern happens at estrus in the cow; it’s caused by NaCl and potassium ions.
What are the two types of cow cervical mucus?
- Sialomucin: mucus of low viscosity; produced by cells in the basal area of the cervical crypts; spermatozoa can swim in it.
- Sulfomucin: highly viscous; produced in the apical portions of the cervical epithelium covering the tips of the cervical folds; washes out the spermatozoa
Describe sperm transport in the uterus
Contractile activity of the myometrium plays a major role in the transport of sperm into and through the uterus; a massive number of sperm invade the endometrial glands; sperm in the uterus elicits a leukocytic response, which enhances phagocytosis.
What is spermophagy?
The uptake of sperm by phagocytes; major mechanism which removes spermatozoa from the female tract
What barriers to sperm transport exist in the utero-tubal junction?
Physical constriction of the lumen (cow: valve can constrict the lumen); mucus barrier (sow); protein signature requirement (mice: recognition of sperm ADAM3 protein)
