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| 31. | ductus venosus | shunt that causes oxygenated blood to bypass the fetal liver on its way to the inferior vena cava |
| 32. | ectoderm | primary germ layer that develops into the central and peripheral nervous systems, sensory organs, epidermis, hair, and nails |
| 33. | ectopic pregnancy | implantation of an embryo outside of the uterus |
| 34. | embryo | developing human during weeks 3-8 |
| 35. | embryonic folding | process by which an embryo develops from a flat disc of cells to a three-dimensional shape resembling a cylinder |
| 36. | endoderm | primary germ layer that goes on to form the gastrointestinal tract, liver, pancreas, and lungs |
| 37. | epiblast | upper layer of cells of the embryonic disc that forms from the inner cell mass; gives rise to all three germ layers |
| 38. | episiotomy | incision made in the posterior vaginal wall and perineum that facilitates vaginal birth |
| 39. | expulsion | second stage of childbirth, during which the mother bears down with contractions; this stage ends in birth |
| 40. | fertilization membrane | impenetrable barrier that coats a nascent zygote; part of the slow block to polyspermy |
| 41. | fertilization | unification of genetic material from male and female haploid gametes |
| 42. | fetus | developing human during the time from the end of the embryonic period (week 9) to birth |
| 43. | foramen ovale | shunt that directly connects the right and left atria and helps divert oxygenated blood from the fetal pulmonary circuit |
| 44. | foremilk | watery, translucent breast milk that is secreted first during a feeding and is rich in lactose and protein; quenches the infant's thirst |
| 45. | gastrulation | process of cell migration and differentiation into three primary germ layers following cleavage and implantation |
| 46. | genotype | complete genetic makeup of an individual |
| 47. | gestation | in human development, the period required for embryonic and fetal development in utero; pregnancy |
| 48. | heterozygous | having two different alleles for a given gene |
| 49. | hindmilk | opaque, creamy breast milk delivered toward the end of a feeding; rich in fat; satisfies the infant's appetite |
| 50. | homozygous | having two identical alleles for a given gene |
| 51. | human chorionic gonadotropin | (hCG) hormone that directs the corpus luteum to survive, enlarge, and continue producing progesterone and estrogen to suppress menses and secure an environment suitable for the developing embryo |
| 52. | hypoblast | lower layer of cells of the embryonic disc that extend into the blastocoel to form the yolk sac |
| 53. | implantation | process by which a blastocyst embeds itself in the uterine endometrium |
| 54. | incomplete dominance | pattern of inheritance in which a heterozygous genotype expresses a phenotype intermediate between dominant and recessive phenotypes |
| 55. | inner cell mass | cluster of cells within the blastocyst that is fated to become the embryo |
| 56. | involution | postpartum shrinkage of the uterus back to its pre-pregnancy volume |
| 57. | karyotype | systematic arrangement of images of chromosomes into homologous pairs |
| 58. | lactation | process by which milk is synthesized and secreted from the mammary glands of the postpartum female breast in response to sucking at the nipple |
| 59. | lanugo | silk-like hairs that coat the fetus; shed later in fetal development |
| 60. | let-down reflex | release of milk from the alveoli triggered by infant suckling |
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