Gametogenesis Part 2 Flashcards
what is oogenesis
primordial cell to ova
discuss oogenesis at prenatal
begins in fetus - primordial germ cell replicate via mitosis
oogenesis at 3rd month
oogonia arranged in clusters surrounded by follicular cells (single flat epithelial cells)
oogenesis at 5th month
oogonia at peak development - 7 000 000
oogenesis at 7th month
majority of oogonia degenerates and those that survive become primary oocytes and enter meiosis 1
about 2000000 survive
primary oocytes + single flat epithelial cell
primordial follicle
discuss oogenesis at antenatal
at birth - all primary oocytes are at prophase of meiosis 1 and rests at diplotene
OMI or oocyte maturation inhibitor arrests oocytes at diplotene = freeze
discuss oogenesis at puberty
only one oocyte reaches full maturity each month - ovarian cycle
meiosis 1 is completed d/t luteinizing hormone (LH) = 2 haploids but only one secondary oocyte survives
if sperm fertilizes it goes to meiosis 2
no sperm egg dies
discuss oogenesis at menopause
there are only 500 eggs available hence there will come a time that there will be no more eggs to ovulate
discuss oogenesis at fertilization
secondary oocyte will enter meiosis 2 but arrests at metaphase - around 3 hrs before ovulation
only upon fertilization will it continue otherwise it degenerates
discuss spermatogenesis in general
begins at puberty when sertoli cells nurture spermatogonium in seminiferous tubules
ends when haploid motile sperm cell sloughs off inner wall of ST
discuss spermatogenesis at primary spermatocyte
produced from mitosis of 1 spermatogonium @ seminiferous tubules
undergoes meiosis 1 = 2 diploid secondary spermatocytes
discuss spermatogenesis at secondary spermatocyte
2 diploid secondary spermatocytes undergo meiosis 2 @ seminiferous tubules = 4 spermatids (haploid)
discuss spermatogenesis at spermatids
matures in sperm with heads and tail = motile
golgi phase of spermiogenesis
spermatid acquires prepared for head, mid piece and tail
golgi appraatus produces lytic enzymes that will form that acrosome or cap
mitochondria will fill in the mid piece
DNA undergoes packing at protamines - inactive
cap phase of of spermiogenesis
golgi surrounds anterior of spermatid = acrosome
tail phase of spermiogenesis
elongation of microtubules on one side of centrioles will form an axoneme in 9 + 2 configuration
pair of microtubules at center surrounded by 9 doublet microtubules
tail is oriented towards center of lumen of ST
maturation phase of spermiogenesis
sertoli cells phagocytosis the remaining cytoplasm and organelles
final product - non motile spermatozoon; sterile
becomes motile in epididymis
migrates to epididymis via spermiation
discuss the head of sperm
has haploid nucleus and acrosome that contains enzymes to penetrate the egg
discuss the middle piece of sperm
full of mitochondria that converts glucose into ATP for tail movement
discuss the tail of sperm
flagellum
this refers to changes to the structure or number of chromosomes
chromosomal abnormalities
discuss deletion
common - short arm of chromosome 5 or cri du chat syndrome
reduced head size and high pitched crying