Exam 5: Spermatogenesis and Oogenesis Flashcards
What is spermatogenesis?
Process of the formation of sperm
What is the site of formation of sperm?
Seminiferous tubule of the testicle
What is spermatogenesis regulated by?
Testosterone
When does spermatogenesis begin?
Puberty
Look at the process of sperm cell development
Look at the process of sperm cell development
What does the pampiniform plexus do?
Cools blood that comes into the testis
Helps recirculate testosterone in the testis
Describe hormone regulation
Testosterone secreted by Leydig cells has a negative feedback
LH stimulates Leydig cells to secrete testosterone
FSH stimulates Sertoli cells to produce inhibin and convert testosterone to estrogen
How is LH released for in spermatogenesis?
Pulsatile fashion
What does the pulsatile fashion of LH release do?
Prevents refractoriness to sustained LH
What is the spermatogenesis secretion of testosterone like?
Short and pulsatile
What is essential for spermatogenesis?
Elevated testosterone in testis
What are the 3 biological events involved in spermatogenesis?
Mitosis
Meiosis
Spermiogenesis
What is mitosis in spermatogenesis?
Proliferation phases which allows for continual supply of germ cells
What does meiosis allow for in spermatogenesis?
Allow for diploid to haploid
Allows for crossing over
Assures genetic diversity
What is spermiogenesis?
Dramatic morphological changes from spermatids to spermatozoa
What happens to spermatagonoia during spermatogenesis?
Migrate along Sertoli cells toward lumen of the tubule
Undergo maturation and become primary spermatocytes
What is occurring during the process of spermatogonia becoming primary spermatocytes? What is special about this process?
Mitosis is occurring here
This is a heat sensitive process
What happens to primary spermatocytes after they undergo meiosis I?
Forms 2 secondary spermatocytes with haploid
What happens to secondary spermatocytes after they undergo meiosis II?
They become spermatids
What is the cycle of seminiferous tubule?
Arbitrarily defined cellular associations that transition one to the next at predictable levels
How many stage does a bull have in the cycle of the seminiferous tubule?
8
How many cycles does complete spermatogenesis take?
4.5
What temperature must spermatogenesis occur at?
3-7 degrees Celsius cooler than the body temperature
What things are involved in the regulation of temperature?
Scrotal sweating
Tunica dartos muscle
Cremastor muscle
Pampiniform plexus
What creates the blood testis barrier?
Sertoli cells are joined by tight junctions which effectively create a barrier from the immune system
What does the blood testis barrier serve to do?
Allow metabolism of developing sperm to occur in a controlled environment
Why are developing sperm not allowed to access the interstitial space?
The immune system will recognize them as foreign
What chromosome do females contribute? Males?
Only X
X or Y
What is the sex of the offspring determined by?
Whether an X or Y bearing sperm fertilizes the oocyte
What is sperm composed of?
Head
Midpiece
Tail
Describe the head of sperm
Contains the DNA
Acrosome cap contains enzymes which aid in fertilization
Describe the midpiece of sperm
Contains mitochondria which provide power for the tail action
Describe the tail of sperm
Flagellum like action provides movement
1-4 mm/minute in fluid environment
What is semen?
Sperm and associate fluid which are ejaculated
What contribute to the fluid volume of semen?
Accessory sex glands
What are the accessory sex glands?
Ampulla
Prostate
Seminal vesicles
Bulbourethral glands
What is oogenesis?
Development of the oocyte
What happens to oogonia during prenatal growth?
They undergo meiosis
Describe what happens to oogonia at birth
They enter meiosis near the time of birth but remain resting in prophase until puberty when meiosis resumes in a few cells each cycle
What is produced following oogenesis?
1 ovum and 3 polar bodies
What are the differences between male and female germ production?
Males constantly replenish germ cells through ongoing mitosis
Females are born with all they will ever have and slowly deplete their supply
Great increase in number of sperm by mitosis in the male
Oogenesis involves only a limited number of oogonia each cycle
