RT Book, Section
A1 Mescher, Anthony L.
SR Print(0)
ID 1184202030
T1 The Female Reproductive System
T2 Junqueira's Basic Histology Text and Atlas, 16e
YR 2021
FD 2021
PB McGraw Hill
PP New York, NY
SN 9781260462982
LK accessmedicine.mhmedical.com/content.aspx?aid=1184202030
RD 2024/04/18
AB The  Female  Reproductive  System  SUMMARY  OF  KEY  POINTSOvaries,  Follicles,  and  OocytesThe  female  gonads,  the  paired  ovaries,  each  have  an  outer  cortex  containing  many  hundreds  of  ovarian  follicles  and  an  inner  medulla  of  dense  connective  tissue  and  large  blood  vessels.The  ovary’s  cortex  is  covered  by  a  cuboidal  mesothelium,  the  surface  epithelium  (or  germinal  epithelium)  that  overlies  a  layer  of  connective  tissue,  the  tunica  albuginea.Before  puberty,  all  follicles  are  primordial  follicles,  formed  in  the  developing  fetal  gonad,  with  each  having  one  primary  oocyte  arrested  in  meiotic  prophase  I  and  a  surrounding  layer  of  squamous  follicular  epithelial  cells.After  puberty,  some  primordial  follicles  develop  each  month  as  growing  primary  follicles,  with  an  enlarging  primary  oocyte  surrounded  by  larger  epithelial  cells  now  called  granulosa  cells.During  follicular  growth,  the  granulosa  cells,  surrounded  by  a  basement  membrane,  become  stratified  and  actively  engage  in  fluid  secretion  and  steroid  hormone  metabolism.Between  the  oocyte  and  the  granulosa  cells,  a  thin  layer  forms  called  the  zona  pellucida,  which  contains  glycoproteins  (ZO  proteins)  to  which  the  sperm  surface  must  bind  to  reach  the  oocyte  at  fertilization.Antral  or  vesicular  follicles  are  larger  and  have  developed  fluid-filled  spaces  among  their  granulosa  cells,  but  the  growing  oocyte  is  still  in  prophase  I.While  the  primary  follicle  grows,  mesenchymal  cells  immediately  around  it  form  the  highly  vascular  layer,  the  theca  interna,  and  a  more  fibrous  theca  externa,  with  smooth  muscle  cells.Endocrine  cells  of  the  theca  interna  secrete  both  progesterone  and  estrogen  precursors,  which  are  converted  by  granulosa  cells  into  estrogen.Antral  follicles  continue  developing  as  mature,  graafian  follicles,  which  have  a  large  antrum  filled  with  fluid,  with  the  large  primary  oocyte  enclosed  by  granulosa  cells  of  the  cumulus  oophorus.Each  month  only  one  graafian  follicle  becomes  a  dominant  follicle  and  undergoes  ovulation;  most  other  developing  follicles  arrest  and  degenerate  with  apoptosis  in  a  process  called  atresia.Ovulation  and  the  Corpus  LuteumOvulation  involves  movement  of  a  very  large,  dominant  graafian  follicle  to  the  ovary  surface  to  form  a  bulge,  completion  of  meiosis  I,  and  release  of  a  polar  body  from  the  oocyte.Rupture  of  the  follicle  and  ovarian  coverings  releases  the  secondary  oocyte,  arrested  now  in  metaphase  II,  and  a  layer  of  attached  granulosa  cells  that  make  up  the  corona  radiata.Cells  of  the  granulosa  and  thecal  layers  left  in  the  ovary  after  ovulation  are  reorganized  under  the  influence  of  LH  to  form  the  endocrine  gland  called  the  corpus  luteum.The  cells  of  the  corpus  luteum  are  granulosa  lutein  cells,  producing  estrogen  and  comprising  80%  of  the  gland,  and  theca  lutein  cells  producing  progesterone.LH  levels  drop  about  2  weeks  after  ovulation,  causing  the  corpus  luteum  to  lose  activity,  degenerate,  and  be  removed  by  macrophages,  leaving  a  temporary  collagen-filled  region  called  a  corpus  albicans.Uterine  Tubes  or  OviductsThe  ovulated  secondary  oocyte  is  swept  into  the  large  open  infundibulum  of  the  uterine  tube,  or  oviduct,  and  enters  that  organ’s  ampulla  region  where  it  degenerates  if  it  is  not  fertilized.Fertilization  involves  sperm  capacitation  in  the  oviduct,  acrosomal  activation,  and  sperm  penetration  of  the  corona  radiata,  and  the  following  events  at  the  oocyte  surface:Surface  ligands  on  one  sperm  first  attach  to  ...