Transcript Development
Development Learning objectives • • • • • Ovulation and fertilization Implantation Embryonic and fetal development Labor and birth Postnatal development Ovulation Spikes in FSH and LH stimulate ovulation of a secondary oocyte Secondary oocytes do not complete meiosis until fertilization Ovulation of a secondary oocyte Egg and sperm Secondary oocyte has a layer of follicular cells and the protective zona pellucida Acrosome of sperm contain enzymes for passing the corona radiata and zona pellucida The acrosome on sperm requires about 7 hrs for activation • Enzymes from the acrosome – Disrupt the attachments between cells of the corona radiata and the zona pellucida – Allows the sperm to reach the oocyte Modern IVF techniques create significant ethical questions • Combined with PCR, pre-implantation genetic diagnosis is possible for 8-cell embryos • A single cell can be sampled • What can be learned about an embryo from looking at its DNA? • The union of the sperm and the egg that results in a cell with 46 chromosomes is called a(n): A) embryo. B) zygote. C) fetus. D) trophoblast. Fertilization until first cleavage Identical and fraternal twins Gastrulation allows formation of differential tissues from the inner cell mass Gastrulation- forming of a gastrula- a primitive gut Ectoderm, endoderm, and mesoderm are formed Ectoderm, endoderm and mesoderm give rise do different tissues • The inner cell mass of the blastocyst undergoes gastrulation, forming ectoderm, endoderm and mesoderm, which will ultimately give rise to all the tissues of the body • When two secondary oocytes are released from the ovaries and are fertilized by different sperm cells, this is called: • A) fraternal twins. • B) identical twins. • C) conjoined twins. • D) clones. Implantation The embryo release human chorionic gonadotropin Alerts the mother’s body to its presence, thereby sustaining the corpus luteum throughout pregnancy The outermost layer of blastocyst cells give rise to the extraembryonic membranes- amniotic sac, umbilical cord and chorionic villi of the placenta The placenta is the interface between fetal and maternal circulation • allows the transfer of oxygen and nutrients from the mother’s blood to the fetus • Prevents the mixing of fetal and maternal blood, allowing for differences in blood type between mother and child Sexual development • Male and female reproductive structures are formed from the same tissue • Differentiated by the presence of absence of the SRY gene region of the Y chromosome • A male has a genetic disease coded for on his Y chromosome. Which parent passed on this trait? • A) The mom • B) The dad • C) Either the mom or dad • D) Neither parent: it is a spontaneous mutation Because organs such as the lungs are not used in utero, fetal circulation is arranged differently from the circulatory pathway of adults Fetal development is most susceptible to birth-defect causing environmental insults between weeks 3 and 16 Growth of the fetus is allometric, and continues to be allometric until development is complete at adulthood Labor is the painful process of birthing a baby, and consists of dilation, expulsion, and placental stages Lactation cannot begin until a baby is delivered • Colostrum and milk both contain antibodies which protect a baby against disease during its infancy • Which of the following functions to maintain the corpus luteum and to stimulate it to continue to produce the hormone progesterone? • A) Human chorionic gonadotropin • B) Progesterone • C) Estrogen • D) Testosterone