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Questions and Answers
Which process is least likely to cause duplication or twinning?
Which process is least likely to cause duplication or twinning?
- Duplication of specific organ-forming regions, termed "fields," after the gastrula stage
- Fertilization of separate ova
- Complete or partial separation of blastomeres and blastocysts during neurulation
- Shared blood supply in completely separated twins (correct)
Twinning arising from three or more zygotes, each with separate fetal membranes and placentas, and differing biological sexes, is best described as which type of twinning?
Twinning arising from three or more zygotes, each with separate fetal membranes and placentas, and differing biological sexes, is best described as which type of twinning?
- Symmetrical monozygotic
- Symmetrical polyzygotic (correct)
- Conjoined symmetrical monozygotic
- Symmetrical dizygotic
If a single zygote completely duplicates during the initial mitotic cleavage, what type of twins will result?
If a single zygote completely duplicates during the initial mitotic cleavage, what type of twins will result?
- Free symmetrical polyzygotic
- Free symmetrical dizygotic
- Free symmetrical monozygotic (correct)
- Conjoined symmetrical monozygotic
Which type of twinning results in nearly complete twins that are fused at a particular site?
Which type of twinning results in nearly complete twins that are fused at a particular site?
What is the specific term for conjoined twins fused at the head, sternum, and abdomen?
What is the specific term for conjoined twins fused at the head, sternum, and abdomen?
What is the term used to describe twins that share one body but have two faces?
What is the term used to describe twins that share one body but have two faces?
Conjoined asymmetrical twins, where one individual is normal and the other is an attached extra body part, are also known by what term?
Conjoined asymmetrical twins, where one individual is normal and the other is an attached extra body part, are also known by what term?
The movement of epithelial cells to the underlying area, which occurs during the formation of the mesoderm, is known as what process?
The movement of epithelial cells to the underlying area, which occurs during the formation of the mesoderm, is known as what process?
The formation of vertebrae involves the grouping of mesenchymal cells into a densely packed subpopulation within mesenchymal tissue. What term describes this process?
The formation of vertebrae involves the grouping of mesenchymal cells into a densely packed subpopulation within mesenchymal tissue. What term describes this process?
Programmed cell death in specific areas, characterized by degeneration and eventual death of cells in necrotic zones, is best described as which process?
Programmed cell death in specific areas, characterized by degeneration and eventual death of cells in necrotic zones, is best described as which process?
Flashcards
Polyzygotic Twinning
Polyzygotic Twinning
Arises from 3+ zygotes, separate membranes/placentas, same/different biological sex.
Monozygotic Twinning
Monozygotic Twinning
Duplication from 1 zygote during 1st mitotic cleavage resulting in identical twins
Siamese Twins
Siamese Twins
Twins fused at a particular site.
Cephalothoracoabdominopagus
Cephalothoracoabdominopagus
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Diprospus
Diprospus
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Heteropagus Twins
Heteropagus Twins
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Delamination
Delamination
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Mesenchymal Aggregation
Mesenchymal Aggregation
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Apoptosis
Apoptosis
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Yolk Sac
Yolk Sac
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Study Notes
- Duplication or twinning may not be caused by sharing a blood supply between completely separated twins.
- Free symmetrical polyzygotic twinning arises from 3 or more zygotes, develops separate fetal membranes and placentas, and may have the same or different biological sex.
- Free symmetrical monozygotic twinning arises from 1 zygote, duplicates completely during the 1st mitotic cleavage, and results in two identical twins.
- Siamese twins results in nearly complete twins that are fused at a particular site.
- Cephalothoracoabdominopagus is the name for fused twins at the head, sternum, and abdomen.
- Diprospus is the term for twins having 2 faces with one body.
- Conjoined asymmetrical twins or heteropagus twins result in fusion with unequal individuals, one is normal and the other is an attached extra body part.
- Delamination is the migration of epithelial cells to the underlying area and is exhibited by the formation of mesoderm.
- Mesenchymal aggregation is the grouping of mesenchymal cells to form a densely packed subpopulation within a mesenchymal tissue and is exhibited by the formation of the vertebra.
- Apoptosis is the programmed degeneration and eventual death of cells in areas called necrotic zones.
- The yolk sac provides nutrition to the chick embryo.
- The allantois allows the exchange of gases between the embryo and its environment.
- The allantois is the extraembryonic membrane that serves as the site of removal or storage of waste products.
- The amnion is an extraembryonic membrane that protects the embryo.
- The amnion and chorion are extraembryonic membranes that form from the somatopleure.
- The allantois and yolk sac are extraembryonic membranes that form from the splanchnopleure.
- The splanchnopleure is formed from the splanchnic mesoderm and endoderm germ layers.
- The somatopleure is formed from the somatic mesoderm and ectoderm germ layers.
- The amnion and chorion form the fetal membrane.
- Syndesmochorial placenta have only two layers of maternal membrane but the fetal membranes are intact
- Endotheliochorial placenta facilitates the trophectoderm's contact with uterine blood vessel endothelium, leading to degeneration.
- Cotyledonary placentas feature villi forming tiny oval/round areas on the chorionic vesicle's external surface, except at the undilated ends.
- Discoid placentas concentrate villi in oval-shaped disks.
- Formation of the neural tube does not happen during the gastrula stage.
- The notochord is not a part of the primitive streak.
- The primitive groove forms when epiblasts in the middle of the primitive streak move to the periphery and ventral region of the embryonic disk resulting in a depressed area.
- The notochord forms when the mesoderm between the primitive streak and hypoblast spreads out to form vacant space cranial to the Hensen's node and epiblasts from the Hensen's node aggregate at the middle of the vacant space.
- The ectoderm germ layer will form on the surface of the embryonic disk.
- The embryonic area is the area in which the embryo will develop.
- The neural plate forms when the ectoderm along the dorsal midline of the embryo thickens.
- The formation of the 3 germ layers is not a part of the neurula stage.
- The neural crest is excluded from the formation of the neural tube during the fusion of neural folds.
- The neural ectoderm is the origin of the neural tube.
- The subcephalic pocket forms the space that separates the head process and blastoderm/embryo.
- The paraxial mesoderm is the origin of the somites.
- The splanchnic mesoderm is the origin of the cardiogenic plate.
- The cardiogenic plates are the origin of the epimyocardium.
- The mesolecithal egg has a moderate amount of yolk with an increasing gradient from the animal pole to the vegetal pole.
- The zona pellucida is not present in a macrolecithal egg.
- Sertoli cells are not spermatogenic cells.
- The golgi apparatus of the early spermatid will form the acrosome.
- The vagina is the area for deposition of spermatozoa in the female reproductive organ.
- Capacitation refers to the removal of surface proteins and alteration of the sperm cell membrane to increase sperm motility.
- The fallopian tube is the site of fertilization in the female reproductive organ.
- The fertilization membrane is formed during fertilization to prevent polyspermy.
- Discoidal cleavage occurs in the small blastodisk or blastoderm on the yolk surface at the animal pole.
- The trophoblast is the flattened outer blastomere that secretes fluid and induces changes in the uterine epithelium during implantation.
- The subgerminal cavity space will be formed when the blastoderm separates from the underlying yolk in a 100-cell embryo.
- Anaphase involves the separation of 2 chromatids from one chromosome and the migration of each chromatid to the opposite poles of the cell during mitosis.
- Rostral refers to the extreme anterior portion of the head of the embryo.
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