Gametogenesis (spermatogenesis) IV Flashcards
(25 cards)
Characteristics of the cells at the start of spermiogenesis?
non-flaggelar haploid round spermatid
First step of spermiogenesis?
Golgi apparatus form the acrosome
What is the acrosome?
organelle of anterior sperm head, covering part of nucleus
What do acrosomes contain?
Hydrolytic enzymes and proteases
Why do acrosomes contain hydrolytic enzymes and proteases?
Allows them to digest the material surrounding the egg to access it
What are protamines?
Small, arginine rich nuclear proteins
Role of promatines?
CHromatin compaction and nuclear remodelling
What type of chromatin does proamatine result in?
Non-nucleosomal
Effect of protamine on transcription?
Almost completely shut down
What state is chromatin at the start of spermiogenesis?
Nucleosomal
What first replaces histones in mice and humans during spermiogenesis?
Transition proteins (Tnp1, Tnsp2)
Which kind of spermatids have Tnp1 and Tnp2?
Round spermatids
What replaces the transition proteins in spermiogenesis?
Protamines:Prm1 and Prm2
Which kind of spermatids have Prm1 and Prm2?
Elongating spermatids
What do promatimes form?
Toroidal sperm chromatin
Benefit of toroidal sperm chromatin?
May give greater packing density
Role of sertoli cells?
“look after” sperm cell precursors
Cells relationship w/ basal lamina during differentiation?
Move away from it
What is TAF4b?
a testis-specific TBP-associated transcription factor
What are TBP-associated transcription factors?
TATA binding protein
What is the absence of TAF4b associated with?
azoospermia
What is azoospermia?
No sperm
What do testicular sperm lack?
Forward motility and the ability to fertilise an egg
When do sperm gain forward motility and fertilising ability?
During epididymal transit
