1 / 8

Human Development

Human Development. Fertilization. Must occur within 24hrs postovulation Requires capacitated sperm (6-8hrs) Secondary oocyte completes Meiosis II once sperm enters oocyte Zygote formed with fusion of male and female pronuclei. Cleavage. Rapid mitotic cell division of zygote

mayes
Télécharger la présentation

Human Development

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Human Development

  2. Fertilization • Must occur within 24hrs postovulation • Requires capacitated sperm (6-8hrs) • Secondary oocyte completes Meiosis II once sperm enters oocyte • Zygote formed with fusion of male and female pronuclei

  3. Cleavage • Rapid mitotic cell division of zygote • 2-cell stage; 36 hours • 4-cell stage; 48 hours • 8-cell stage; 72 hours • Morula - solid ball of cells (blastomeres) at 96 hours • Takes 4-5 days to travel from uterine tubes to uterine cavity

  4. Implantation • Morula develops into bastocyst, a hollow ball of cells differentiated into inner cell mass and trophoblast • Trophoblast embeds into endometrium • secretes enzymes, HCG • chorionic villi • attachment occurs 7-8 days after fertilization

  5. Embryonic Development • Extends from the 2-8th week after conception • Inner cell mass differentiates into: • Ectoderm - epidermis of skin, entire nervous system • Endoderm - functional lining of the digestive and respiratory system • Mesoderm - forms muscle, bone, blood vessels, and kidneys

  6. Fetal Membranes • Chorion - fetal part of the placenta, outermost membrane • Amnion - fluid filled sac covering embryo and later fetus • Yolk sac - source of nourishment for embryo; early site of blood formation • Allantois - developing umbilical cord and developing bladder of fetus

  7. Placenta Formation • Functions to exchange waste products and blood gases • Chorionic villi penetrate into the decidua basalis of the endometrium • Chorion - fetal portion • Decidua basalis - maternal portion • Placenta previa

  8. Hormones of Pregnancy • HCG secreted by the chorion maintains corpus luteum • FSH repressed, cycle stops • Progesterone maintains endometrial lining • Placenta secretes estrogen and progesterone • Corpus luteum degenerates • Late pregnancy: relaxin secreted

More Related