Spermatogenesis and Semen Evaluation Flashcards
3 goals of spermatogenesis
Produce spermatozoa
Replenish supply of primordial stem cells
Create genetic diversity
Spermatozoa
Cells that are capable of fertilisation
3 phases of spermatogenesis
Proliferation phase (mitosis) (spermatocytogenesis) Meiotic Phase (spermatidogenesis) Differentiation phase (spermiogenesis)
Key parts of gross anatomy of testis
Head of epididymis
Testis
Tail of epididymis
Vas deferens
Sertoli cells
Support the process of spermatogenesis (structurally, provides nutrients and fluids, clears waste)
Tall cells from basement membrane to the lumen
Forms tight junctions (creates physical barrier)
Name of the barrier that divides the seminiferous tubule
Sertoli cell barrier
Sperm-testis barrier
Blood testis barrier
2 compartments that the seminiferous tubule is divided into
Basal compartment
Adlumenal compartment
Spermatogenic cell types (and what compartment)
Spermatogonia (basal)
Spermatocytes (adlumenal)
Spermatids (adlumenal)
Spermatozoa (adlumenal)
Proliferation phase
Spermatogonia (spermatogonial stem cells)
Cells divide and replicate by mitosis
Parent cell to 2 daughter cells diploid and genetically identical
Number of divisions depends on species
Some spermatogonia B cells go back to beginning (not all of them will become spermatozoa)
Intercytaplasmic ridges- joined together (have to do things in synchrony)- divide and replicate together
Meiosis Phase
2 phases
Cross over and random reassortment of DNA- creates genetic diversity
End up with genetically unique haploid cells
Start of prophase- primary spermatocytes
After prophase- secondary spermatocytes
Prophase relatively long (1/3 of whole process)
After second phase- spermatids- haploid
Differentiation phase
Starts with spermatids, ends with spermatozoa
No cell division or replication
Changing from round cell to morphological function
Needs to be able to get through zona pellucida and fertilise ovum- head
Needs to be able to move itself- tail- energy-mitochondria
4 phases
Spermiogenesis
After gets released into lumen
4 phases of differentiation phase
Golgi
Cap
Acrosomal
Maturation
Spermatozoa structure is ………… in each species
Different
Head of spermatozoa
Nucleus and acrosome and post-nuclear gap
Shape varies across species
Acrosome contains hydrolytic enzymes required for penetration of zona pellucida
Tail of spermatozoa
Self powered flagellum
Composed of: middle, principle and terminal piece
Overall length of spermatozoa
~60um
DSO correlates with ………, good measure of …………
Size, fertility
Cycle of seminiferous epithelium
How long it takes to go from germ cell (primordial stem cell) to final
1-2 months across species
The Spermatogenic wave
Differences at any given instant in time along the seminiferous tubule:
Stage of spermatogenic cycle differs in adjacent regions of tubule
Finite region of tubules releasing sperm at given time
Each section contains different stages of development
Endocrine regulation
Hypothalamus releases GnRH to anterior pituitary which releases LH and FSH
LH- leydig cells (intersitial compartment between seminiferous tubules)
Leydig cells produce testosterone (partly influences sertoli cells)
Negative feedback
FSH- sertoli cells
What happens in:
The testes
The head and body of the epididymis
The tail of the ejaculation
Spermatozoa Produced
Mature
Stored until ejaculation
If male is overworked, fertility …………..
Decreases
Process never speeds up
Ejaculate decreases
Clinical relevance
Time for spermatozoa to be produced
Sperm-testis barrier
Semen evaluation
What should you record in semen evaluation
Volume, colour, appearance
EEJ is more/less dilute than natural service
More dilute
Mass motility/wave motion
How many spermatozoa are motile
Score 1-5
Low microscope power
Scoring of mass motility
5= ~90% active (billowing clouds) 4= 70-80% active (clouds) 3= 45-65% active (fair), more grainy, less cloudy 2= 20-40% active (slow) 1= <20% active (poor) , very slow 0= nothing, all dead
Progressive motility
How many move in straight line
Higher power on microscope
Identify 10 separate spermatozoa and see if they are moving straight or in circles
Repeat and average to get a proportion that have got progressive motility
Gross appearance
Score on how dense it looks
Thick creamy, creamy, thin creamy, milky, cloudy, clear watery
Careful of pus (makes it look dense)
Morphology
Head and tail abnormalities
Tail- effects its ability to move progressively
Head- effects its ability to get through zona pellucida
Head abnormalities
Crater defect
Tapered heads
Ruffled acrosome
Knobbed acrosome
Tail abnormalities
Coiled tail
Double midpiece
Folded tail
Detached head
Morphology defects
Primary vs secondary
Compensable vs non-compensable
Can measure density with……..
A Haemocytometer
Things spermatozoa are sensitive to
Temperature (cold shock)- keep sample, glassware and staining fluids warm (~37*C)
Water
Bright light, blood, detergents, cigarette smoke, rubber bung in syringes
