Studydroid is shutting down on January 1st, 2019

by mtoom


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What are the major functions of the ovary? (2)
  • Producing ova (oogenesis)
  • Secreting hormones (steroidogenesis)
What are the functional units of ovaries? *
Follicles
Name the 5 stages of follicle development and describe which parts are non-cyclical and cyclical. *
Non-cyclical
  • 1. Primordial follicle
  • 2. Primary follicle (uni-)

Cyclical
  • 3. Primary follicle (multi-)
  • 4. Secondary follicle
  • 5. Graafian follicle 
Regarding primordial follicles:
  • When/how do they develop?
  • What do they become? 
  • In 6th week of embryonic development, primordial germ cells (oogonia) migrate from yolk sac to gonadal primordia
  • Undergo mitosis
  • Become encapsulated by pre-granulosa cells and arrest in 1st meiotic division, and are called primary oocytes at this point

There are no oogonia in newborns
Regaring primary follicles (uni-):
  • When/how do they develop?
  • What do they become?
  • Recruitment into primary follicles starts in fetal life and continues post-natally until ovarian reserve depleted
  • Leaves behind ~1000 primordial follicles at menopause

Appears to be gonadotropin-independent
Describe primordial follicle stage (3) 
  • [stage 1, non-cyclic]
  • Primary oocyte surrounded by single layer of flattened follicular cells
  • Large nucleus
  • Prominent nucleolus
Describe primary follicle (uni-laminar) (4)
  • [stage 2, non-cyclic]
  • Enlarged oocyte
  • Follicular cells begin to undergo mitosis
  • Granulosa cells are cuboidal
  • Formation of zona pellucida (thick layer of glycoprotein) begins

Regarding the antrum:
  • What is the antrum?
  • When is the antrum first seen?
  • The antrum has key roles in what? 
  • Fluid-filled cavity
  • First seen in follicular phase
  • Key role in follicular growth, oocyte maturation, ovulation
At the antral stage, what becomes critical determinant of follicle growth and survival?
FSH
Describe primary follicle (multi-laminar) (4)
  • [stage 3, cyclic]
  • Zona pellucida
  • Primary follicle/oocyte continues to enlarge
  • Granulosa cells several cell layers thick = zona granulosa
Describe secondary follicle (3)
  • [stage 4, cyclic] 
  • Zona granulosa proliferates, fluid-filled spaces appear (i.e. antral lakes), follicular fluid accumulates
  • Oocyte almost full size
  • Theca folliculi
Describe Graafian follicle (5)
  • [stage 5, cyclic]
  • Follicular antrum ("antral lakes") enlarges markedly
  • Zona granulosa forms layer around periphery
  • 1o oocyte surrounded by corona radiata
  • Distinct theca interna
  • Follicle bulging under ovarian surface
What happens in the zona reaction? (4)
  • What's the purpose of the reaction? 

BRICK WALL prevents polyspermy
  • Acrosome reaction (modified lysosomes in head of sperm)
  • Rapid depolarization of oolemma
  • Cortical granules fuse with oolemma
  • Proteases in granules cross-link proteins on zona pellucida, blocks further sperm
As a result of LH surge, ovulation occurs. The 2o oocyte leaves with the corona radiata.
  • The corona radiata serves what purpose for the follicle? 
"Packed lunch"
What happens to corpus luteum?
  • No fertilisation of ovum, corpus luteum of menstruation
  • Fertilisation of ovum, becomes corpus luteum of pregnancy, and it is maintained by hCG

Invariably, it eventually becomes the corpus albicans
What is the corpus luteum?
The leftovers of the Graafian follicle after ovulation occurs
The theca interna and granulosa cells are now called what?
  • Theca Lutein
  • Granulosa Lutein
What is the histology of corpus albicans?
Inactive fibrous tissue
  • Secretory cells undergo autolysis, phagocytosed by macrophages 
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