Anatomical  Errors  and  Maldevelopment. — From  an  anatom-
ical standpoint,  errors  in  development  and  lack  of  development  of
the  genital  passages  and  organs  may  play  an  important  part  in
sterility.  Such  maldevelopment  may  actually  prohibit  intercourse,
as  in  absence  of  the  vagina;  or  prevent  conception,  as  when  the
uterus,  ovaries,  or  tubes  are  missing.  Absence  of  the  vagina  is
rare  and  when  present  is  always  associated  with  an  undeveloped
condition  of  the  uterus  and  ovaries,  and  such  cases  offer  no  hope
of  a  cure  from  the  viewpoint  of  sterility.  Atresia  of  the  vagina  is
a  more  common  condition  and  occurs  when  the  fusion  of  the  ducts
of  Miiller  fails  to  reach  the  surface.  The  existing  barrier  is  an
obstructing  membrane  that  lies  just  above  the  hymen  and  this
can  be  easily  divided,  thus  establishing  the  patency  of  the  vagina.
Occasionally  cases  are  met  where  the  vagina  is  congenitally  too
narrow  to  admit  of  intercourse  (stenosis)  or  so  constricted  in  its
middle  third  (hour-glass  contraction)  as  to  render  proper  intercourse
difficult.  An  abnormally  rigid  hymen  may  for  a  while  prevent  inter-
course, but  its  resistance  is  usually  eventually  overcome  and  it  does  not
often  require  cutting.
