Module 5 part 1: Gameteogenesis and ART Flashcards
What is gametogenesis known as in males?
spermatogenesis –> produces spermatozoa
What is gametogeneis?
process whereby a haploid cell (n) is formed
from a diploid cell (2n) through:
-meiosis
- cell differentiation
What is gametogenesis known as in females?
oogenesis –> forms ova (eggs)
When do males start producing sperm and where does this occur?
- when they reach puberty (10-16 years old)
- in the testes –> SEMINIFEROUS TUBULES (kept separate from systemic circulation by the blood-testes barrier)
What is the Blood-testes barrier?
- formed by Sertoli cells
- prevents hormones and constituents of the systemic ciruclation from affecting the developing sperm
- prevents the immune system from recognizing the sperm as foreign
What are the two common types of cells in spermatogenesis and what are their jobs?
- sertoli cell
- “nurse cell”
- form blood-teste barrier
- support developing sperms
- produce fluid and control release of sperm into lumen
- secrete inhibin –> slows sperm production - leydig cell
- mixed in walls of tubules
- produce high levels of testosterone once male reaches adolescence
What are 4 hormones involved in spermatogenesis?
- Lutenizing hormone (LH)
- Follicle stimulating hormone (FSH)
- Testosterone
- inhibin
What does LH and FSH do in spermatogenesis?
stimulatory effect
stimulate spermatogenesis and testosterone secretion by the testes
What does testosterone and inhibin do in spermatogenesiS?
inhibitory effect
- inhibit secretion of GnRH by hypothalmus
- inhibit secretion of LH and FSH by pituitary
What is spermatogonia?
the initial pool of diploid
cells that divide by mitosis to give two identical cells
What is the difference between type A and type B spermatogonia? (NEED TO CLARIFY THIS ONE)
type a = primary spermatocytes that undergo MEIOSIS
type B = replicate by mitosis several times to form identical diploid cells (primary spermatocytes)
Is there 2 stages to meiosis?
YES
*Meiosis I produces two haploid cells;
known as secondary spermatocytes.
*Meiosis II produces four haploid cells, known as spermatids
What is spermiogenesis?
when spermatid mature and differentiate into sperm
what is spermiation?
when the cytoplasmic bridges break down and the spermatids are released into the lumen of the seminiferous tubule
How long does spermatogenesis take?
approximately 70 days
What is capacitation?
when the sperm removes the cholesterol and glycoproteins from it’s head
- allows the sperm to bind to the zona pellucida of the egg cell in female reproductive tract
What is seminal fluid responsible for?
nutritional support —> has lots of sugars for ENERGY!
suppresses possible immune response by female
What makes up most of the fluids in semen?
seminal fluid
What are 4 reasons a male may be infertile?
- low sperm concentration
- poor sperm motility
- abnormal morphology
- aberrant epigenetic
reprogramming of the genome
There is significant increase of structural abnormalities with paternal age. true or false
true
Not all chromosomes are susceptible to non-disjunction. true or false
false –> they are
Meiotic errors are very common in humans. true or false
true
majority of the errors are
chromosome breaks and acentric fragments for the structural anomalies of sperm. true or false
true
What are some sperm abnormalities that can occur?
- double head
- giant head
- amorphous head
- pinhead
- tapered head
- constricted head
- double tail
- coiled tail
- no tail (spermatid)