Gametogenesis (Exam 1) Flashcards
What are primordial germ cells
undifferentiated cells that migrate to the gonadal ridge to become either sperm or egg cells
Where do primordial germ cells originate from
epiblast
Where do primordial germ cells migrate
to the yolk sac and then back to the body cavity where they situate themselves in the thoracic region
What does the epiblast form
the layers of the trilaminar embryo
What is the area in the thoracic region where they land
genital ridge
What does the genital ridge end up forming
the ovary or teste
Where do primordial germ cells originate from
epiblast
Where will trilaminar embryo be formed
from cells of the epiblast
What are primitive sex cords
cells surrounding primordial germ cells that originate from genital ridge
What is formed in males from sex cord cells
sertoli cells
What is formed females from sex cord cells
follicular cells
What are Sertoli cells
supporting cells to forming sperm
What are Follicular cells
surround oocyte
When will primordial germ cells come out of dormant state in males
puberty
What is the role of Leydig cells in male gametogenesis
produce testosterone
What does testosterone production do
stimulate sertoli cells and sperm generating cells to start producing sperm
What type of cells are contained within the seminiferous tubules
sertoli and sperm-forming cells
Where will mature cells be seen in the seminiferous tubules
towards the center
Where will immature cells be seen in the seminiferous tubules
on the outside (they move in as they mature)
What is the summary of meiosis in males
Spermatogonia Primary spermatogonia 2 Secondary spermatogonia 4 Spermatids Mature Sperm
Where does meiosis occur in males
in the male reproductive tract
How many types of spermatogonia are there
two
What is spermiogenesis
formation of sperm from spermatids
What occurs during spermiogenesis
formation of acrosome
formation of tail and neck
condenses DNA material
gits rid of cytoplasm and extraorganelles
What is the function of the acrosome
to help sperm cross zona pellucida and plasma membrane in oocytes
Why is the cytoplasm shed in spermiogenesis
to make the sperm more streamlined to swim
What is capacitation
shedding of glycoproteins on the outside of the sperm
Where does capacitation occur
in the female reproductive tract in response to uterine fluids
In females how are oogonia produced
female germ cells undergo a series of mitotic divisions after being invested by the sex cords and differentiate into oogonia
When does meiosis start for oogonia
week 12 of development
What occurs during meiosis for oogonia
it is halted and becomes dormant until puberty
What forms a primordial follicle
single, flat layer of cells that form around a primary oocyte
How is oocyte division arrested
follicle cells produce hormone OMI
What does OMI hormone stand for
oocyte maturation inhibitor
What does OMI do
stop the oocyte from finishing division
What is the corpus albicans
degenerated corpus luteum, a scar tissue in the ovary that is the remnant of the follicle
What is the key feature in identifying a graafian follicle
antrum
What is a key feature of a primary follicle
cuboidal follicle cells
Where will immature follicles be seen in an ovary
less mature are on the outside of the ovary
What are the hormones involved in ovulation
LH
FSH
What is FSH released in response to
GnRH
What does FSH do
stimulate follicles to grow
When does FSH production occur
during the follicular phase it increases and is highest just prior to ovulation
What does FSH causes the production of
estrogen
When does LH rise
during the follicular phase
What does LH stimulate the production of
progesterone
What does progesterone do
prepare the uterus for implantation
What are the two stages of the ovarian cycle
follicular phase
luteal phase
How will changes in LH and FSH levels affect follicles in the ovary
cause 5-12 primordial follicles to multiply and increase in size and become primary follicles
What is the zona pellucida
a glycoprotein coat produced by the oocyte and follicular cells
What is important about the zona pellucida for fertilization
sperm must penetrate this layer via the acrosome
What type of follicle will have an antrum
Graafian follicle
What are the two connective tissue layers found on a graafian follicle
theca externa
theca interna
What is the function of the theca interna
secrete steroids (estrogen and progesterone
What is the function of the theca externa
connective tissue layer with little function
How many primary follicles will develop into graafian follicles
1