|
| 1. | acrosomal reaction | release of digestive enzymes by sperm that enables them to burrow through the corona radiata and penetrate the zona pellucida of an oocyte prior to fertilization |
| 2. | acrosome | cap-like vesicle located at the anterior-most region of a sperm that is rich with lysosomal enzymes capable of digesting the protective layers surrounding the oocyte |
| 3. | afterbirth | third stage of childbirth in which the placenta and associated fetal membranes are expelled |
| 4. | allantois | finger-like outpocketing of yolk sac forms the primitive excretory duct of the embryo; precursor to the urinary bladder |
| 5. | allele | alternative forms of a gene that occupy a specific locus on a specific gene |
| 6. | amnion | transparent membranous sac that encloses the developing fetus and fills with amniotic fluid |
| 7. | amniotic cavity | cavity that opens up between the inner cell mass and the trophoblast; develops into amnion |
| 8. | autosomal chromosome | in humans, the 22 pairs of chromosomes that are not the sex chromosomes (XX or XY) |
| 9. | autosomal dominant | pattern of dominant inheritance that corresponds to a gene on one of the 22 autosomal chromosomes |
| 10. | autosomal recessive | pattern of recessive inheritance that corresponds to a gene on one of the 22 autosomal chromosomes |
| 11. | Braxton Hicks contractions | weak and irregular peristaltic contractions that can occur in the second and third trimesters; they do not indicate that childbirth is imminent |
| 12. | blastocoel | fluid-filled cavity of the blastocyst |
| 13. | blastocyst | term for the conceptus at the developmental stage that consists of about 100 cells shaped into an inner cell mass that is fated to become the embryo and an outer trophoblast that is fated to become the associated fetal membranes and placenta |
| 14. | blastomere | daughter cell of a cleavage |
| 15. | brown adipose tissue | highly vascularized fat tissue that is packed with mitochondria; these properties confer the ability to oxidize fatty acids to generate heat |
| 16. | capacitation | process that occurs in the female reproductive tract in which sperm are prepared for fertilization; leads to increased motility and changes in their outer membrane that improve their ability to release enzymes capable of digesting an oocyte's outer layers |
| 17. | carrier | heterozygous individual who does not display symptoms of a recessive genetic disorder but can transmit the disorder to his or her offspring |
| 18. | chorion | membrane that develops from the syncytiotrophoblast, cytotrophoblast, and mesoderm; surrounds the embryo and forms the fetal portion of the placenta through the chorionic villi |
| 19. | chorionic membrane | precursor to the chorion; forms from extra-embryonic mesoderm cells |
| 20. | chorionic villi | projections of the chorionic membrane that burrow into the endometrium and develop into the placenta |
| 21. | cleavage | form of mitotic cell division in which the cell divides but the total volume remains unchanged; this process serves to produce smaller and smaller cells |
| 22. | codominance | pattern of inheritance that corresponds to the equal, distinct, and simultaneous expression of two different alleles |
| 23. | colostrum | thick, yellowish substance secreted from a mother's breasts in the first postpartum days; rich in immunoglobulins |
| 24. | conceptus | pre-implantation stage of a fertilized egg and its associated membranes |
| 25. | corona radiata | in an oocyte, a layer of granulosa cells that surrounds the oocyte and that must be penetrated by sperm before fertilization can occur |
| 26. | cortical reaction | following fertilization, the release of cortical granules from the oocyte's plasma membrane into the zona pellucida creating a fertilization membrane that prevents any further attachment or penetration of sperm; part of the slow block to polyspermy |
| 27. | dilation | first stage of childbirth, involving an increase in cervical diameter |
| 28. | dominant lethal | inheritance pattern in which individuals with one or two copies of a lethal allele do not survive in utero or have a shortened life span |
| 29. | dominant | describes a trait that is expressed both in homozygous and heterozygous form |
| 30. | ductus arteriosus | shunt in the pulmonary trunk that diverts oxygenated blood back to the aorta |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|