Development of pregnancy

Development of pregnancy

  • Submitted By: ladhaf1
  • Date Submitted: 04/21/2013 11:07 AM
  • Category: Miscellaneous
  • Words: 2366
  • Page: 10
  • Views: 128


2 Embryonic stage – from fertilization through week 8. –embryo

3 Fetal period – week nine until birth – fetus

4 Pregnancy – fertilization, implantation, embryonic and fetal development – results in birth 38 weeks later (40 weeks after last menstrual period) 3 trimesters-

5 First – all major organ systems appear – most susceptible to environmental effects

6 Second – development of organ systems

7 Third – growth of fetus


9 Fusion of haploid sperm nucleus with the haploid secondary oocyte nucleus to form the diploid zygote.

1 Occurs in fallopian tube -12-24 hours after ovulation

2 Only about 200 sperm reach site –Viable for 48 hours after deposition

3 Pregnancy most likely to occur –in a window that is 2 days before ovulation to 1 day after

4 Sperm swim from vagina to cervix; from here on mostly contractions of uterus and tubes that propel sperm forward

5 Prostaglandins in semen stimulate uterine motility

6 Capacitation – sperm undergo changes that prepare the membrane to fuse with oocyte

7 Cholesterol, proteins and glycoproteins are removed from head of sperm

8 Acrosome of sperm contain enzymes which penetrate

1 Corona radiata – granulosa cells surrounding secondary oocyte

2 Zona pellucida – receptors for sperm (ZP3), sperm binds to this and begins acrosomal reaction – to digest path through zona

3 First sperm to penetrate zona pellucida fuses with oöcyte nucleus –oöcyte undergoes second meiosis

4 Male pronucleus fuses with female pronucleus forming diploid zygote


6 Fertilization by more than one sperm –polyspermy

9 To prevent polyspermy – oöcyte membrane depolarizes –fast block to polyspermy

10 Exocytosis of molecules which inactivate ZP3 receptors –hardens zona pellucida –slow block to polyspermy


12 Dizygotic (fraternal) twins result from release and...

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