Sperm Transport and Maturation in the Female Reproductive Tract Flashcards
Characteristics of the phallus in birds
- mechanism of erection is lymphatic rather than vascular
2. semen is transfered via a groove along the outside of the phallus rather than a tube in the middle
What are the two types of penises in mammals?
musculocavernous
fibro-elastic
Describe the musculocavernous penis
- large amount of erectile tissue
- found in horse, dog, cat, and human
Describe the fibro-elastic penis
- fibroelastic tissue with smaller amounts of erectile tissue
- tends to have a sigmoid flexure
- found mostly in artiodactyls (ruminants, pigs)
What other components are found within the penis?
- paired corpora cavernosa enclosed in tunica albuginea
- os penis in some species (dogs, raccoons, seals)
- barbs on the glans in some species (rabbit, cat, ferret)
- corpus spongiosum (surrounds urethra)
What is the purpose of the retractor penis muscle? (not in all species)
keeping the non-erect penis within the prepuce
What are the 4 phases of erection?
flaccid
tumescence
stable erection
detumescence
Describe the flaccid state
maintained by tonic contraction of s.m. in the corpora and arteries supplying them under the influence of sympathetic adrenergic input
Describe erection
- psychic stimuli acting on the brain and tactile stimuli on the penis result in decreased sympathetic tone and increased parasympathetic tone causing relaxation of penile arterioles and smooth muscle of the cavernous sinuses
- NO and cGMP mediate relaxation and blood flows into the erectile corpora
- venous drainage is then compressed
Describe detumescence
- sympathetic tone increases and parasympathetic tone decreases
- synthesis of NO and cGMP ceases
- venous outflow is re-established and blood expelled from the cavernous sinuses returns the penis to a flaccid state
Ejaculation consists of what 2 components?
emission
expulsion
What is the function of the spinal ejaculation generator?
integrate sensory inputs from the genitalia that will trigger ejaculation with the autonomic and motor outputs required to generate the ejaculatory response
Where are sensory receptors located on the penis?
penile skin
glans
urethra
within the corpus cavernosum
What is involved in emission?
getting all the components of ejaculation into the pelvic urethra
What happens during emission?
- secretion of fluids from the accessory glands
- contraction of the cauda epididymis and vas deferens containing the sperm
- closure of the sphincter at the bladder neck and the external urethral sphincter
What does parasympathetic supply stimulate in emission?
secretion of fluids by the epithelial lining of the accessory glands
What does sympathetic supply stimulate in emission?
- muscle contraction of the accessory glands to expel the fluid
- cauda epididymis and vas deferens to move sperm
- contracts the bladder neck and external urethral sphincters
What is the order of contraction of the gland systems?
bulbourethral or prostatic fraction first
sperm-rich fraction next
gland fraction last
What is expulsion?
rhythmic contractions of urethral smooth muscle and the striated bulbospongiosus muscle that expel semen from the urethra
What follows expulsion?
refractory period where sexual arousal is inhibited
When is sperm motility activated?
during the process of emission and ejaculation when they are mixed with the accessory sex gland fluids
(show progressive motility at this stage)
What is progressive motility?
when the sperm show relatively low-amplitude wave motion of the tail which gives little lateral head movement and fairly straight line motility
When do sperm develop hyper-activated motility?
at the time of capacitation
Name some factors that can influence the mechanisms and speed of sperm transport to the site of fertilization
- species variation in size and morphology of sperm
- duration of estrus and the timing of ovulation in relation to estrus
- anatomical site of sperm deposition
- the life span of sperm within the female tract
