Spermatogenesis Flashcards
Spermatogenesis definition
Process of producing the spermatozoa
Consists of cell divisions and morphologic changes to produce germ cells
Takes about 2 months (varies between species)
Where does Spermatogenesis take place?
Seminiferous tubules in the testicle
Phases of spermatogenesis
Proliferation (mitosis)
Meiosis
Differentiation
Goals of spermatogenesis
Continuous supply of male gametes (up to decades)
-Stem cell renew to continue process throughout animals life
Genetic diversity
Immunologically privileged site → Germ cells are not destroyed by the immune system
-Sertoli cells
Deliver the male genetic material
Mechanism to prevent germ cell destruction by the immune system
Immunologically privileged site
Endocrine requirements for spermatogenesis and oogenesis to take place
1.adequate secretion of GnRH from the hypothalamus
- FSH and LH secretion from the AP
LH- Leydig, theca cells
FSH-Sertoli, granulosa cells - Secretion of gonadal steroids (testosterone and estradiol)
Proliferative phase of spermatogenesis
Start with spermatogonia and end with primary spermatocytes
Germ cells divide by several mitoses to increase the yield of spermatogenesis;
Renew of spermatogonia steam cells
Production of undifferentiated spermatogonia
Production of primary spermatocyte
Happens in basal compartment
A(2n)–> B (2n) –> primary spermatocyte (2N)
Meiotic phase of spermatogenesis
Recombination of genetic material
Homologous chromosomes move apart (meiosis I)
Chromosome number is reduced by half (meiosis II)
Primary spermatocytes (2n)
Meiosis I → Prophase I: DNA replication and crossing over
Secondary spermatocytes (N)- alloploid cell (now could be recognized as non-self since not 2n)
Meiosis II
Spermatids (rounds) (N)
Once sperm reaches the ________ cell stage it could be identified as non-self
Secondary spermatocyte (N)- Allopoid cell
Immunologically privileged site so won’t be destroyed
Differentiation stage of spermatogenesis
No further cell division
Morphological changes:
Round spermatid Spermatozoa
Nucleus: become highly condensate
Acrosome: is formed (hydrolytic enzymes)
cell becomes motile -> development of flagellum
Energy: mitochondrial helix (movement)
Spermiation is the process of…
Releasing immature spermatozoa from the Sertoli cells into the lumen of the seminiferous tubules to travel to the epididymis (epididymal transit)
Epididymal transit effect on the sperm
Finishes going through reactions to allow it to be ready for ejaculation and fertilization
Sperm is then stored in the tail of the epididymis until needed
Parts of the sperm
Head
Shape: it varies among species
Nucleus: genetic material, condensed chromatin
Acrosome: hydrolytic enzymes
Penetration in the oocyte during fertilization process
Mid piece
Tail
Self powered flagellum
Capitulum
Middle piece
Principal piece
Terminal piece
