Lecture 2- Human Reproduction Flashcards
(42 cards)
When does gamete formation occur in humans?
-Starts in males at puberty and theoretically can go on until death (sperm) (may be other problems e.g. erectile dysfunction)
What was the youngest mother on record?
-Lina Vanessa Medina, became a mother to a baby boy at 5 years and 7 months of age (1939) - A Mexican girl gave birth when she was 9 years old (2013)
What does the male reproductive system look like?
-on the way the liquid is taken from prostate gland + bulborethral= nourishes the sperm, if issues then problems with reproduction
How many chromosomes etc. do humans have?
-46 -22 autosomes -2 sex chromosomes = X and Y -female= XX -male= XY
What does homologous mean?
-one pair from mother, other from father
What is spermatogenesis like?
- meiosis once puberty reached
- spermatids (immature) 8.3 weeks from start to end
- so having sex every day not good to get pregnant
Where does spermatogenesis take place?
-seminiferous tubules
What are the parts of a sperm?
- Acrosome – contains enzymes to penetrate zona pellucida
- Nucleus – contains compacted chromosomes
- Midpiece – mitochondria provide energy for movement
- Tail - swimming
What does spermatogenesis looke like?
-
Where is sperm collected and stored?
-collected in duct and stored in epididymis
What is the composition of semen?
-
What is classified as normal sperm?
-average 20-120 million sperm/ mL -280 000 000- 500 000 000 sperm/ejaculate
How many sperms reach the position of the egg in the oviduct?
-about 200
Below which point are men considered infertile?
-below 20 million/mL
What is the average volume of ejaculate?
2-6mL -average is 2.75 mL (5mL= 1 teaspoon)
What is the WHO definition of normal sperm count?
• the concentration of spermatozoa should be at least 20 million per ml. • the total volume of semen should be at least 2ml. • the total number of spermatozoa in the ejaculate should be at least 40 million. • at least 75 per cent of the spermatozoa should be alive (it is normal for up to 25 per cent to be dead). • at least 30 per cent of the spermatozoa should be of normal shape and form. • at least 25 per cent of the spermatozoa should be swimming with rapid forward movement. • at least 50 per cent of the spermatozoa should be swimming forward, even if only sluggishly.
What is the study suggesting that the volume of ejaculate has been in decline in society?
- study that says that male ejaculate volume is decreasing
- maybe pollutants or lifestyle
What is azospermia?
- no or low sperm count
What is necrospermia?
- dead sperm
What is oligospermia?
- sperm with defects -can have 2 heads, defects in tail, fused heads etc. -motility issues
What can the sperm insufficiencies be also a result of?
-Mutation: 10 gene loci on Y chromosome that are expressed in the testis and important for male fertility eg DAZ gene
-on the Y chromosome
-it can be a micro deletion or a mutation
What can the sperm insufficiencies be also a result of (another)?
-Antibodies in male or female -Even the male can produce antibodies to his own sperm
What are some of the solutions to male problems?
-When there are some sperm
What is ICSI (Intracytosplasmic sperm injection)?
-can inject a sperm into the egg -one sperm is enough -select a viable one A: If: low sperm count or motility poor sperm morphology (oligospermia) antibodies in male or female Then: viable sperm selected from ejaculate B: If: azospermia (no sperm) and necrospermia (dead or immobile sperm Then: viable sperm from epididymis and/or testis
