Flashcards in Spermatogenesis Deck (48)
Where are sperm made and stored?
→ In the testes
→ stored in the epididymis
What contracts during ejaculation?
→ The vas deferens
Where do the sperm travel to after the vas deferens?
→ Seminal vesicle which contribute seminal fluid
→ move to the prostate which also contribute secretions
Where does the vas deferens meet the urethra?
→ In the prostatic gland
What is responsible for erections?
→ Hydrostatic pressure
Where are the testes located?
→ in the scrotum outside the body cavity
Why are the testes located outside the body?
→ Optimum temperature for sperm production
→ overheating reduces sperm count
What is the normal volume of the testes and how is this measured?
What do the tubules lead to?
→ Rete on one side
What does the rete lead to?
→ Epididymis and vas deferens
What is 90% of the testis made up of?
→ seminiferous tubules
Where is the site of spermatogenesis?
→ Seminiferous tubules
How long does it take for sperm to go from the basal side to the lumen?
→ 74 days
What are sertoli cells held together by?
→ Tight junctions
What are tight junctions for?
→ preventing an immune response against sperm cells
Describe the formation of spermatozoa
→ The sperm start as spermatogonia which are diploid
→ they replicate by mitosis and form 2 types of cell
→ type A and type B
→ type A is used as the template and replicates again
→ type B moves into the adluminal compartment and becomes a primary spermatocyte
→ the primary spermatocyte undergoes meiosis I and become secondary spermatocyted
→ 2ndary spermatocytes divide to form 4 daughter cells (meiosis II)
→ these are spermatids
What are the walls of the seminiferous tubules made from?
→ Tall columnar endothelial cells which are Sertoli cells
What are spaces between the seminiferous tubules filled with?
→ lymphatic vessels
→ Leydig cells
How long does the cycle of spermatogenesis take?
→ 74 days
How often do new cycles of spermatogenesis occur?
→ every 16 days
Summarise spermatogenesis in 3 steps?
→ mitotic proliferation of spermatogonia
→ Meiosis and development of spermatocytes
→ spermiogenesis , elongation, loss of cytoplasm and movement of cellular content
What do spermatids remain connected by and why?
→ A cytoplasmic bridge
→ they form a syncytium allowing synchronous development
What are the 2 differences between oogonia and spermatogonia?
→ Cannot make more oocytes by mitosis
→ sperm can divide mitotically
→ limited supply of eggs
What do Leydig cells do?
→ LH binds
→ Convert cholesterol into testosterone
What receptors do Sertoli cells have?
What is the function of Leydig and Sertoli cells?
→ Leydig cells make testosterone
→ Sertoli cells make ABP which makes testosterone more soluble so it can be concentrated in the lumen
What happens if you take anabolic steroids?
→ Decrease in LH and FSH
→ Testicular atrophy occurs
What happens during an erection?
→ Vasodilation of the corpus cavernosum
→ Partial constriction of the venous return
What does the autonomic nervous system do during an erection?
→ Coordinated smooth muscle contraction of the vas deferens, glands and urethra