chapter 14 genital system Flashcards
how many days does it spermatogenesis take
65-75 days
with what cell does spermatogenesis begins
spermatogonia
what are spermatogonia
stem cells
Some spermatogonia remain near the basement membrane of the seminiferous tubule in an undifferentiated state to serve as reservoir cell for the future cell division and subsequent sperm production.
The rest of the spermatogonia lose contact with basements membrane squeeze through the tight junctions of blood-testis barrier undergo developmental changes and differentiate into primary spermatocytes.
primary spermatocytes
diploid (2n) that is they have 46 chromosomes
what happens after the primary spermatocytes are formed
each primary spermatocyte replicates its DNA and then meiosis begins
what happens is meiosis I
homologues pair of chromosomes line up at the metaphase plate and crossing over occurs. Then the meiotic spindle pulls one duplicated chromosome of each pair to an opposite pole of the dividing cell
what is the name of the 2 cells fromed by meiosis 1
secondary cells
what each secondary cells has?
each secondary cell has 23 chromosomes the haploid number
what happens meiosis II
the chromosomes line up in a single file along the metaphase plate and two chromatid of each chromosome separate
how many haploid cells result from meiosis II
4
what are the names of the cells from meiosis II
spermatids
a single primary spermatocyte therefore produce
4 spermatids with haploid number vie two rounds of cell division with haploid number
what is the name of the last phase
spermiogenesis maturation of of haploid spermatidis into sperm
what happens during spermatogensis
during sperm proliferate they fail to complete cytoplasmic separation cytokinesis. The cells remain in contact via cytoplasmic bridges through their entire development. This patterns of development most likely account for the synchronized production of sperm in any given area of seminiferous tubule.
