Spermatogenesis Flashcards
Where do germ cells come from and which part of the gonad do each type colonise ?
Primordial germ cells come from Allantois
X germ cells colonise cortex of gonads
Y germ cells colonise medulla of male gonad
Approximately how many sperm cells are produced each day ?
200 million
How many oocytes are produced by the female ?
400 in lifetime
1 per month
What are the two main functions of meiosis in gametogenesis ?
Reduce number of chromosome to 23 in gamete
Ensure that each gamete is genetically unique
which mechanisms of meiosis ensure genetic variation ?
Crossing over (between homologous chromosomes ) Independent assortment of bivalent across metaphase plate Random segregation
Where does spermatogenesis occur ?
In testes , between Sertoli cells of the seminiferous tubules
Where are spermatogonia kept in the testis ?
Basal compartment , separated by tight junction from other cellular compartment (blood testis barrier )
What are the two types of spermatogonium and how is that relevant ?
Ad spermatogonium
Ap spermatogonium
When spermatogonia divide by mitosis , the Ad stays in stock and the Ap will give type B spermatogonium then primary spermatocytes at puberty which will divide by meiosis
Ad spermatogonium ensure constant renewal of number of germ cells
Differentiation of spermatids into spermatozoa (sperm ) is called …?
Spermiogenesis
What is spermiation ?
Release of spermatids into seminiferous lumen
What happens in spermiogenesis ?
- Spermiation
- Remodelling of spermatid through seminiferous tubules, rete testis , ductuli efferentes and epididymis to form spermatozoa
How are the spermatids moved to the epididymis ?
Non motile
Due to secretion from Sertoli cells and peristaltic contractions
What is spermatogenic cycle ?
The time taken for reappearance of a stage of spermatogenesis in the same segment of a seminiferous tubule
How long is a spermatogenic cycle ?
16 days
What is spermatogenic wave ?
Distance between two same stage of spermatogenesis in tubule
