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Lecture 31

BIOL 3070 Lecture Notes - Lecture 31: Seminiferous Tubule, Seminal Vesicle, Spermatogenesis

2 pages26 viewsWinter 2017

Course Code
BIOL 3070

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Lecture 31: Reproduction:
Male reproductive system:
oThe testicular structures, organization, copulatory organs and hormonal regulation are
different between mammals and insects
oBasic components are similar however: testis, vas deferns, ejaculatory duct, penis,
accessory gland
Gamete production: spermatogenesis is similar between mammals and insects
oImmature germ/stem cell in male is known as spermatogonium
oMitosis of the spermatogonium where one cell replaces the original spermatogonium 
one of the two daughter cells will divide mitotically to form 4 daughter cells known as
primary spermatocytes  resting phase so chromosomes are duplicated (THUS WE
HAVE A PAIR OF EACH CHROMOSOME, that is 2 from dad and 2 from mom) (n to 2n)
oEach Primary spermatocytes  meiosis forms 2 secondary spermatocytes (haploid,
2n, separation of the homologous pair) known as reductional division (homologous
chromosomes are reduced)  secondary spermatocytes  2nd meiosis  forms 2
daughter cells known as spermatids (thus haploid, 1n)  maturation of 16 spermatids 
o1 daughter cell of mitotic division of spermatogonium  forms 16 spermatozoa
Cytoplasm and non essential organelles are lost, leaves small abundant
mitochondria (important for production of ATP in the sperm usually changing of
fructose from the fluid of accessory cells)
Formation of flagellum after changing the cytoskeleton
Mature spermatozoa are stored in epididymis
oSertoli cells:
Provide structural and metabolic support
Found from the basement membrane of the seminiferous tubules
Maintaining the blood testis barrier: it is different than the normal
blood, maintained by the tight junctions between the sertoli cells
Secretes testicular fluid
Secrete androgen binding protein which concentrates testosterone into
a high concentration (which is important for spermatogenesis)
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