Term
| What are the steps of meiosis I ? |
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Definition
Interphase
-DNA replicates (4c - 2n)
Prophase 1
Lepotene - chromatin condenses
Zygotene - homologous pairing
Pachytene - crossing over & recombination
Diplotene - synaptonemal complexes dissociate
Diakinesis - chiasma disappear, homologues repel
Metaphase 1
-centromere of homologue binds to spindle fibre
Anaphase 1
-homologous pairs separate
Telophase 1
-chromosomes migrate to opposite poles, cell divison (2c - 1n) |
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Term
| What are the steps of meiosis II? |
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Definition
Prophase II
-spindle fibers rearrange, chromosomes recondense
Metaphase II
-chromosomes align along spindle equator
Anaphase II
-sister chromatids separate to opposite poles
Telophase II
-daughter cell nucleus has one set of chromosomes (1c-1n) |
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Term
| What is the role of sertoli cells? (5) |
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Definition
-blood testis barrier
-provides nutrients & other factors which control spermatogenesis
-fluid pumping during final maturation of sperm
-produce androgen-binding protein & inhibin
-express FSH receptors |
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Term
| What hormone regulates the action of sertoli cells? |
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Definition
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Term
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Definition
final stage of spermatogenesis
-spermatids mature into motile spermatozoa |
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Term
| Describe the process of spermiogenesis (5 steps) |
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Definition
1. Spermatids come in contact with Sertoli cells
2. Nucleus condenses
3. Acrosoal cap forms
4. Tail develops based on a template provided by distal centriole
5. Mitochondria concentrate into the sheath of the middle portion of the spermatid |
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Term
| What is the contractile lattice of a spermatozoa's tail made of? |
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Definition
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Term
| Describe the structure & role of Leydig cells (4 points) |
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Definition
Interstitial cells found in spaces between tubules
-highly perfused (vascular)
-synthesize androgens (testosterone)
-express LH receptors |
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Term
| Describe the spermatogenic cycle spacially and in terms of time |
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Definition
Time:
-specific stages coordinated along a tubule in a precise, repetitive manner
Time:
-a section of tubule will always have an identifiable stage of sperm development
-cycle takes approximately 13.5 days |
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Term
| Name & describe the roles of the accessory sex glands |
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Definition
Ampular gland - enlarges ductus defferent
Vesicular gland - secretes fructose, vitamins, prostaglandins, proteins
Prostate - alkaline substance to enhance motility
Bulbo-urethral - alkaline substance to neutralize acidity, mucus to lubricate vagina |
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Term
What is the role of each of the following as it relates to spermatozoa
Fructose
Vitamins
Prostaglandins
Proteins |
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Definition
Fructose
-energy for sperm
Vitamins
-mobility & survival
Prostaglandins
-mobility & survival
Proteins
-coagulation |
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Term
| Why are bulls able to ejaculate more frequently than boars? |
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Definition
bulls release less sperm per ejaculation, leaving enough in reserve for multiple ejaculations
boars essentially 'empty the tank' |
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Term
| What are the steps of spermatogenesis? |
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Definition
Spermatocytogenesis
spermatognia -> spermatids
Spermiogenesis
spermatids -> spermatozoon |
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Term
| What might trigger arousal? |
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Definition
olfactory stimuli
visual stimuli
auditory stimuli
etc. |
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Term
| Describe the process of arousal (5 steps) |
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Definition
1. Sensory stimulation
2. Stimulation of nerves in supraoptic & paraventricular nuclei (hypothalamus)
3. Release of oxytocin from posterior pituitary
4. Contraction of smooth muscle in distal tail of epidydimis & ductus deferens
5. Transport of spermatozoa into a ejaculatory position |
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Term
| Describe the process of ejaculation |
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Definition
1. Penis inserted into vagina (intromission)
2. Sensory stimulation of glans penis (temp & pressure)
3. Sudden contraction of urethralis, bulbospongiosus & ischiocavernosus muscles
4. Expulsion of semen |
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Term
| List & explain some of the components you may find in an extender used for cryopreservation |
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Definition
Nutrient - egg yolk, whole homo milk
Buffer - citrate (maintain stable pH)
Antimicriobials - penicillin, minosin
Cryoprotectant - 6-12% glycerol to protect sperm from crystals if frozen |
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