gritti 18 Flashcards
(42 cards)
internal genitalia of the female
ovaries, oviduct, vagina and uterus
where does oogenesis take place?
in the ovaries.
oocytes starts to be produced before birth but then they are arrested in some steps of their meiotic cycle and they complete their second meiotic division only after fertilization
2 main sex hormones produced in the ovaries
progesterone->important for pregnancy
estrogen->for the correct functionality of the female reproductive system
2 layers of the capsule that cover the ovaries
-germinal epithelium: simple cuboidal epithelium
-tunica albuginea: layer of dense connective tissue that supports the epithelium
the ovarian parenchyma is divided in 2 parts
cortex: outermost part, highly cellular connective tissue, where we can find ovarian follicles->in this region we can find oocytes at different maturation stages
medulla:loose connective tissue, vascularized (ovarian arteries and veins), lymph vessels and nerves entering at the hilum
where are positioned primordial follicles in the cortex?
in the outermost part.
as they mature, they go deeper down in the parenchyma
what are ovarian follicles?
sites in which oocytes develop
structure of primordial follicles
-already present before birth
-oocyte arrested in meiotic phase I+one layer of follicular cells (squamous cells around the oocyte)
structure of primary unilaminar/multilaminar primary follicles
in each menstrual cycle after puberty some primordial follicles get activated and develop into primary follicles.
unilaminar:
oocyte+one layer of granulosa cells (developed from follicular cells)
multilaminar:
oocyte+multiple layers of granulosa cells
what is the hormone that dictates this primary maturation step of the primordial follicles?
FSH->follicular stimulating hormone
then granulosa cells will produce other hormones that will help in keeping the primary follicles in their quiescent state
zona pellucida
thin region made of glycoproteins around the oocyte formed by the oocyte itself during the development from primordial to primary follicle
-fundamental for the entrance of the spermatozoa and its binding
-essential to not make entry additional ones
the stromal cells between follicles proliferate during the maturation of the primordial follicles, dividing in two regions:
theca interna cells: producing steroid
theca externa: fibroblasts and smooth muscle cells merging with the surrounding stroma
->supportive role
when can we say that we have a multilaminar primary follicle?
when we have
-oocyte
-multilayer of granulosa cells
-initial differentiation of theca cells
secondary or antral follicle
the granulosa cells of the primary follicle will start to produce a liquid that will form sparse cavities that will merge into a big antrum.
the layer of granulosa cells around the oocyte is called corona radiata.
the part that connects the granulosa layer with the oocyte is called cumulus oophorus
stratum granulosum: multilayer of granulosa cells that surround the antrum->avascular
theca folliculi:
stroma cells divide into theca interna and theca externa
mature or graffian follicle
-terminal step of maturation
-largest antrum
-largest oocyte
-the theca folliculi is well organized
-theca interna: vacuolated cells
-theca externa: fibroblasts and smooth muscle cells (flatten) that merge with the stroma
between the theca interna and the granulosum layer there is a basement membrane
the theca interna cells produce androgens
and the granulosa cells in the stratum granulosum convert them into estrogens
when do we see the appearance of the basement membrane between the theca interna and the granulosa layer?
in the secondary or antral follicle
is the granulosa layer vascular or avascular?
avascular
theca interna and externa show blood vessels
what is the stigma?
a witish ischemic area formed as a consequence of the bulging of the mature follicle with the tunica albuginea
(when the dominant follicle is releasing the oocyte from the ovary during ovulation)
Luteinising hormone
granulosa cells in the mature follicle produce estrogens that stimulate the production of LH.
LH is the key hormone for ovulation
corpus luteum
-what remains after ovulation
-if there is no egg fertilization, the corpus luteum begins to degenerate, infiltration of macrophages that make it become the corpus albicans
-if there is fertilization, we start to produce the human chorionic gonadotropin hormone and the corpus luteum itself becomes a progesterone-secreting structure which helps the progression of the pregnancy
the corpus luteum has to be infiltrated with what to generate the corpus albicans?
collagen and few fibroblasts
athtretic process
the follicles that do not undergo ovulation become athretic
-condensation of nuclear chromatin
-shrinkage of the cytoplasm of follicular cells and of the oocyte
-collapse of the zona pellucida
-thickening of the basal membrane that separate TI from the granulosa layer
-macrophages enter the degenerating structure to clean up the debris
uterine tubes structure
-infundibulum with fimbriae (that helps the trapping of the oocyte from the ovary to the tube)
-ampulla
-isthmus
-intramural (uterine) part
the wall of the oviduct is composed of 3 layers
the mucosa
-simple columnar epithelium with ciliated and non ciliated cells (secretory peg cells with short microvilli)
-lamina prorpia of loose connective tissue
in the infundibulum part there are the fimbriae
->evaginations
thick muscolaris
inner circular and outer longitudinal layer of smooth muscle cells (at least 2 layers can be more)
thin serosa
simple squamous epithelium covered by a thin layer of connective tissue
