Embryology Flashcards
When does Spermatogenesis begin?
- in puberty
What are the phases of spermatogenesis ?
- Proliferative phase
- Meiotic phase
What occurs during the proliferative phase ?
- Retinoic acid at puberty induces Spermatogonia to increase mitosis
Describe the Meiotic phase
- produces haploid spermatids
What occurs post-meiotic phase ?
- post meiotic shaping = Spermiogenesis
- this produces spermatoza
Describe Capacitation
= final maturation of sperm occurs in the female reproductive tract
Where is spermatoza stored?
- it’s released from testis & stays in the epididymis
What is an egg surrounded by?
- egg is enveloped by a layer of follicular cells = Cumulus
- Corona Radiata = innermost layer of Cumulus cells
- Zona pelludica = separate thick matrix beloew the corona radiata
Describe Oocyte content
- nutritive proteins -> yolk proteins produced in the mothers liver
- ribosomes & tRNA
- mRNA
- Morphogenic factors
What is the cumulus important for?
- key for egg translocation to the ampulla
Describe how uterine muscle contractions affect sperm
- sperm can be found in the oviduct in 30 mins as its transported there by uterine contractions
Describe Sperm rheotaxis
- sperms recieve directional info from the flow of liquid in the oviduct
How does the ampulla extend the fertilisation window?
- Oviduct collects & release “packets” of capacitated sperm to extend the fertilisation window
What changes occur when a sperm becomes Hyperactive?
- cholesterol = removed by Albumin in female
- then receptors bind the egg Zona Pellucida are exposed
Where does un-capacitated sperm temporarily bind?
the Isthmus
Describe the Acrosome Reaction
- inner cell membrane fuses with outer membrane of the acrosome
- exposure of proteins like Izumo to merge with the egg membrane
-Izumo bind the egg & this recruits the egg membrane protein CD9
Define Cleavage
- rapid cell division that divide the Zygote cytoplasm into many cells
When does mammalian cleavage occur ?
12-24hrs apart
What cleavages establish the major body axes ?
- 1st cleavage = Meridianl
- 2nd cleavage = Equatorial & meridional
When does the genome become transcriptionally active?
- very early at 8-cell stage (3rd cleavage)
What does 8-cell stage undergo?
Compaction
What results from Compaction?
- blastomers express E-Cadherin & form a ball
- then then become flat & tightly bind together
What does division of the 8-cell compacted stage produce?
- A 16-cell morula
