Spermatogenesis Part 2 Flashcards
What must spherical spermatids do?
- Must condense nuclear DNA (grows tail)
- Form a cell that become motile for ertilization
During the Goligi phase (spermatid) what occurs?
- initial acrosome formation
- Initial tail development, translocation of centrioles
*Proximal ceontriol
*Distal centriol
What is a proximal centriol? What is a Distal centriol?
- Attachment point of tail (flagellum)
- Central portion of tail or axoneme (tail fibres)
What occurs during the cap phase?
- Acrosomic vesicle flattents and “caps” the nucleus
- Primitive tail grows from distal centriole
- Acrosome membrane formed (outer and inner)
- Production of hydrolyic enzymes (Acrosinm hyaluronidase, zona lysin, esterases, acid)
What occurs in Acrosome reaction ?
- Exocytosis during fertilization
- Digest zona pellucida
What occurs in the Acrosomal phase?
- Acrosome covers 2/3 nucleus, nucleus elongates
- Manchette microtubules form: become postnuclear cap
- Neck & annulus formation
What is an Annulus?
Junction between midpiece & principle piece
What occurs in the maturation phase (The final sperm assembly (FSH dependent))?
- Spermatid becomes a spermatozoon
- Mitonchondria surround mid-piece in helical fashion
- Completion of tail
- Spermiation
What does the completion of tail consist of?
- Mid-piece
- Principal piece
- Terminal piece
What is Spermiation?
The release of sperm from sertoli cells into the lumen of the seminiferous tubules
What is necessary to transcript? What is necessary to translate?
- Needs chromosomes
- Needs ribosomes
What can the spermatozoon do?
- Sperm chromatin are compacted and condensed
- DNA is protected by disulfide bonds
- Sperm do not transcribe or translate protein
What does the ultrastructure of sperm consist of?
- Head
- Midpiece
- Principle Piece (tail)
What attaches the head to the tail? What gives the neck flexibility? Metabolic power plant is what piece?
- Capitulum
- Laminated columns
- Mitochondrial helix
How is the arrangement of the principle piece?
- Unique fiber arrangement (9+9+2) contract/release to create movement
* 2 central fivrils through all tail pieces
* 9 double fibrils through mid and principal pieces
* 9 course outer fibers mid piece only
How does the testis produce sperm on a continual basis?
Through the cycle of the seminiferous epithelium
What are the layers of skin of the scrotum?
- Scrotal skin
- Tunica dartos
- Scrotal fascia
- Pariental vaginal tunic
- Visceral vaginal tunic
What is the cycle of seminiferous epithelium (describes process in time)?
Progression of sperm through a series of cellular associations (stages) at one location along a seminiferous tubule
What does the seminiferous epithelium consist of?
- Stage = specific cellular associations
- Stage duration = time for completion of one cell stage
- Cycle = progression through the sequence of all stages (there are 8 stages)
- Cycle duration = time required to complete one cycle
For spermatogenesis how many cell cycles does it need to be completed? How many times does sperm need to repeat this process?
- Takes 8 stages to complete
- Sperm must repeat this process 4.5 times to become mature spermatids
How many generations are in Stage 1? How many are in Stage 4? What is the difference between the 2?
- 4 generations
- 5 generations
- Stage 4 spermatids are more elongated and advanced than those in stage 1
When are elongated spermatids ready for release?
Stage 8
In stage 4 where do the spermaozoan go?
In stage 8 they are ready to release elongated spermatoza into the lumen
Are all zones ready for sperm to be released? If not why?
- No, only certain zones where sperm are ready to be released.
- All other zones are just in the preparatory stage.
How long does the seminiferous epithelium process take for:
The bull, boar ?
- 13.5 d bull
- 8.3 d boar
Why must the seminferous cycle be understood clinically?
to determine potential affected phases like testes insult (chronic heat stress)
What is the spermatogenic wave?
Differences in time along length of seminiferous tubule
What is the purposes of the sequentila ordering of stages along length of seminiferous tubule?
The purpose is to provide a constant supply of sperm for epididymis
How can one determine sperm production? What is it dependent on?
- Dependent on testicular size
- Sertoli cell numbers
Which animals contain pendulous testes? How is it measured?
1.Bull, Ram
2.Scrotal circumference (tape)
Which animals contain testes close to the body? How are they measured?
- Boar, stallion, cat, dog
- Measured by scrotal width and length (caliper)
What are some indications of male fertility?
- Sperm producing ability
- Viability of sperm
- Morphologically abnormalities
- Functionally normal spermatozoa
How does one asses sperm viability?
By microscope (there are manyn ways to assess viability) including staining sper with dyes
What are factors that help with sperm assessment?
- Motility is highly correlated to viability
- Morphology
What is Gross motility? What is Progressive motility
- The % of total ejaculate moving
- % of sperm swimming in a progressive linear fashion
What does morphology determine? How often do sperm have abnromal sperm?
- The % of sperm that deviate from normal shape
- All ejaculates have abnormal sperm (5-15%)
What is the % that determines the cut-off value? When would it start to decrease fertility?
- 30% is what determines the cut-off value
- 20% start to observe decreased fertility, depends on abnormality
Where do Abnormalities normally develop?
- Faulty differentiation inside testes
- Faulty epididymal transit or maturation
* Presence of distal cytoplasmic droplets leaving tail
What are the classification of sperm abnormalities
They can be classified as either head (primary) or tail (secondary) abnormalities
How do tail abnormalities normally occur?
They are due to improper handling of ejaculated sperm, such as inducing cold shock
What are other factors that cause poort sperm function?
- Abnormal DNA (replication, meiosis, environmental damage)
- Abrnomal biochemical composition of sperm membranes (acrosome, plasma, nuclear)
- Plasma membrane protein deficiencies)
- Faulty response to stimuli in female tract (immune response)
- Enviornmental stressers ( Temperatures, fever, sickness, decreased nutrition, mineral imbalance, toxins)
Where do head defects normally occur?
They occur in testis due to defect
What is a TUNEL Assay?
They detect apoptotic cells by detecting DNA nicks
