Gametogenesis Flashcards
(56 cards)
Describe the process of spermatogenesis
Spermatagonium divide (mitosis) to give primary spermatocytes (2n). Then they divide again by meiosis to give two 1n secondary spermatocytes. The second round of meiosis is what gives 4 spermatids. Then spermeiogenesis will differentiate them into spermatozoa.
Distinguish between a spermatogenic cycle and a wave.
A cycle is a measure of time- time taken for reappearance of the same stage of spermatogenesis to appear at a specific location within the tubule- 16days.
A wave is a measure of space- distance between the same stage of spermatogenesis within a tubule.
What is the role of the rete testis?
Concentrates sperm
What is the function of the epidydimus?
Stores the sperm
What is the function of the reproductive tube in males that cystic fibrosis patients may lack?
Transport the sperm out of the scrotum to the urethra. It is in the Vas Defrens that the seminal vesicles make their secretions.
What are the bulbourethral glands?
The Cowper glands contribute to <1% of the ejaculate by producing mucoproteins that lubricate and neutralise any acidity from urine in the distal urethra.
What do the seminal vesicles add to the ejaculate?
70% of ejaculate is the amino acids, fructose, citrate and prostaglandins secreted here.
How does the prostate change the ejaculate?
Proteolytic enzymes and zinc.
Zinc may be there to slow sperm down until hey reach the female genital tract. 25% of final ejaculate.
Outline the anatomical relationship between the prostatic urethra and the prostate.
The urethra runs through the prostate gland.
Describe the ovarian cycle
Prenatal stage, astral and preovulatory stage
How is ovulation controlled.
LH surged
What happens in ovulation?
The oocyte perforates the ovary. Fimbriae catch the oocyte and fuel it into the infundibulum
Contrast oogenesis and spermatogenesis.
Females produce few gametes (1/cycle), Males produce 200 million sperm/day
Males make 4 spermatids from meiosis, women make one oocyte and 3 polar bodies.
Oogenesis starts as a foetus, spermatogenesis only starts at puberty.
Lifelong or till menopause
Motile gametes- sperm, fixed ovum.
Last meiosis stage in gonads for men, oviduct for women
Males continuously produce sperm, women intermittently ovulate (only 400 opportunities to reproduce)
What is spermiation?
Spermatids released into seminiferous tubule
What is the name given to the process of spermiation remodelling of spermatids to spermatazoa and the movement of the sperm through the peristaltic epidydimus?
Spermiogenesis
Outline the structure of sperm.
Nucleus covered by plasma membrane and acrosome.
Midconnecting piece mae up of centriole and mitochondria.
The motile tale.
Outline the structure of sperm.
Nucleus covered by plasma membrane and acrosome.
Midconnecting piece mae up of centriole and mitochondria.
The motile tail.
What is the final maturation step for a sperm to become motile?
Capacitation-removal of glycoproteins and cholesterol from its membrane. This allows sperm to bind zona pellucida.
What stimulates capacitation by the sperm signalling pathway?
The environment of the female genital tract.
What is the acrosome reaction?
Allows sperm to penetrate zona pellucida.
What is the final maturation step for a sperm to become motile?
Capacitation-removal of glycoproteins and cholesterol from its membrane. This allows sperm to bind zona pellucida.
This must be faked in IVF or sperm aren’t fertile
How do female gamete stocks vary?
100% before birth.
Stock declines due to atresia
Menopause
When does maturation of oocytes start?
Before birth- germ cells arise from the yolk sac, colonise the gonad cortex and become oogonium.
How do oogonia proliferate?
mitosis
