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Bio II > Lecture 17- Development II > Flashcards

Lecture 17- Development II Flashcards

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Biology 101 flashcards
1
Q

What happens to the cell cycle after cleavage?

A

The cell cycle resumes normal functions. Cell division slows.

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2
Q

Morphanogenesis

A

Cellular & tissue-based process by which animal body takes shape. Occurs during gastrulation and organogenesis.

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3
Q

Gastrulation

A

Hollow blastula becomes gastrula (layered embryo)
3 germ layers:
Ectoderm
Endoderm
Mesoderm

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4
Q

Gastrulation in Sea Urchins

A

Involves cell migration, invagination- infolding
Forms archenteron- early gut tube
Blastopore- open end of archenteron- becomes anus
2nd opening becomes mouth
Cells at vegetal pole (bottom) migrate into blastocoel
Vegetal plate forms-> cells flatten, fold inwards
Archenteron forms-> cells at tip extend toward opposite wall, contact opposite wall
Archenteron fuses with blastocoel wall-> digestive tube formed. present: 3 germ layers
mouth
anus
cilia

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5
Q

Gastrulation in Birds

A

Doesn’t occur like we see in echinoderms because there is too much yolk. Instead we have an active cap where gastrulation takes place. Meroblastic cleavage.

2 layers in active cap: Hypoblast and epiblast
(Epiblast is on outer part, furthest from egg, hypoblast is closest to egg)

Epiblast cells migrate inward. They either go up and push the hypoblast (becomes endoderm), move laterally and go to the sides (becomes mesoderm), or stay at the bottom of the epiblast (becomes ectoderm).

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6
Q

Primitive Streak

A

Blastopore, directs movements associated with gastrulation

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7
Q

Involution

A

Cell Migration

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8
Q

Hypoblast Cells

A

Contribute to sac around yolk
Connection between yolk and embryo
Do not contribute to embryo itself

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9
Q

Gastrulation in Humans

A

End of cleavage-> blastocyst has formed
Mammalian version of blastula
Arrive at uterus ~6 days after fertilization

Blastocyst
100 cells around central cavity
Trophoblast: Outer single layer of cells
Inner cell mass: Cluster of cells. The inner cell mass becomes the embryo, and is the source of embryonic cell lines.

Implantation
Trophoblast contacts uterine lining- secretes enzymes
-> Erode area of endometrium
-> Embryo penetrates
-> Thickens, extends projections into endometrium

Gastrulation
Takes 1 week- 2nd-3rd week of pregnancy
Inner cell mass forms flat disc- 2 layers (Epiblast and Hypoblast)

Cell Fates
Some epiblast stays in place
-> Ectoderm
Some epiblast migrates in between
-> Mesoderm
Some epiblast migrates & mixes with hypoblast
-> Endoderm

Human Gastrula
3 layers
- Ectoderm
- Endoderm
- Mesoderm
Also contains extraembryonic membranes: Chorion, amnion, yolk sac, allantois
Functions:
- Contain fluid
- Form blood vessels (Gas exchange, food/waste)

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10
Q

Organogenesis (basic)

A

Process of organ formation
Embryo begins to increase in size
Nervous system 1st to develop in most vertebrates

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11
Q

Neurulation

A

Process of forming nervous system
Cells of dorsal mesoderm (notochord) induce dorsal ectoderm to flatten and thicken.
Dorsal ectoderm becomes neural plate, then folds inward to become neural tube
Becomes central nervous system. Anterior portion is brain, and remainder is spinal cord.
Folic acid deficiency can cause problems with development.

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12
Q

Cells of neural crest

A

Form nerves, teeth, and skull bones

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13
Q

Somites

A

Blocks of mesoderm cells lateral to notochord
- Segmented/serially repeated structures
- Ribs, vertebrae, associated muscles

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14
Q

Early Human Development

A

Most radical changes for mother and embryo
Implanted embryo secretes hCG (Human chorionic gonadotropin)-> Acts like LH
Maintains progesterone and estrogen from corpus luteum during 1st trimester

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15
Q

Placenta

A

1st 2-4 weeks, nutrients directly from endometrium. Trophoblast mixes with endometrium -> placenta.

Placenta
Organ of exchange between mother and embryo
Provides nutrients, O2
Removes waste, excreted by mother
Umbilical cord connects embryo to placenta

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16
Q

Twins

A

Identical (Monozygotic)- Shared placenta

Fraternal (Dizygotic)- Separate placentas

Inner cell mass can split during 1st month-> 2 groups of cells-> identical

17
Q

Birth

A

Begins with labor
Uterine contractions- push fetus, placenta out of body
Regulated by prostaglandins, hormones (estradiol, oxytocin)

18
Q

Positive or negative feedback during labor?

A

Positive

19
Q

What is the function of human chorionic gonadotropin (hCG)?

A

Promotes the maintenance of the corpus luteum which allows the corpus luteum to secrete progesterone.

20
Q

Which type of cleavage pattern do sea urchins undergo?

A

Holoblastic

21
Q

The ____ is the bag of waters in which a human fetus develops.

A

Amniotic sac

22
Q

_____ is the process whereby an embryo develops neural folds.

A

Neurulation

23
Q

In which region of the body does cleavage occur in humans?

A

Oviduct

24
Q

What is the early blastocyst composed of?

A

Inner cell mass / Trophoblast / Blastocoel

25
Q

When is the first time an embryo physically grows following gastrulation?

A

Neurulation

26
Q

The _____ is a layer of cells forming the outer ring of the blastocyst that combines with the maternal endometrium to form the placenta.

A

Trophoblast

27
Q

During neurulation, the mesoderm gives rise to the _____.

A

Notochord

28
Q

The _____ secretes proteolytic enzymes to break down the endometrial extracellular matrix to allow for implantation of the blastocyst in the uterine wall.

A

Trophoblast

29
Q

The notochord induces the formation of the _____ .

A

Neural plate

30
Q

The neural plate undergoes a series of folds and becomes the _____.

A

Neural tube

31
Q

_____ is the process whereby the trophoblast thickens and extends fingerlike projections into the endometrium.

A

Implantation

32
Q

What does the neural tube develop into?

A

Anterior → brain / Posterior → spinal cord

33
Q

_____ are blocks of cells that lie in the mesoderm, bilateral to the neural tube (notochord) and contribute to repeating, segmented structures.

A

Somites

34
Q

Which germ layer does the neural crest develop from?

A

Ectoderm

35
Q

What is the main function of the placenta?

A

Gas exchange (both oxygen and waste)

36
Q

The placenta and the developing fetus are connected by the _____.

A

Umbilical cord

37
Q

_____ is a hormone for the maternal recognition of pregnancy produced by trophoblast cells that are surrounding a growing embryo, which eventually forms the placenta after implantation.

A

Human chorionic gonadotropin (hCG)

Bio II (28 decks)

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