Animal Reproduction and Development Flashcards
(86 cards)
1
Q
~Asexual Reproduction
A
● Produced offspring genetically identical to the parent
● Includes budding, fragmentation/regeneration, parthenogenesis
2
Q
~Budding
A
● Involves the splitting off of new individuals from existing ones
● Hydra
3
Q
~Fragmentation and regeneration
A
● Occurs when a single parent breaks into parts htat regenerate into new individuals
● Sponges, planaria, starfish
4
Q
~Parthenogenesis
A
● Involves the development of an egg without fertilization
● Resulting adult is haploid
● Honeybee, whiptail lizards
5
Q
~Sexual reproduction
A
● Each offspring is the product of both parents
6
Q
~Epididymis
A
● Tube in the testes where sperm gain motility
7
Q
~Leydig cells
A
● Clusters of cells located between seminiferous tubules that produce testosterone
8
Q
~Prostate gland
A
● Large gland that secrete semen directly into the urethra
9
Q
~Scrotum
A
● Sac outside the abdominal cavity that hodes the testes
● Cooler the temperature there enables sperm to survive
10
Q
~Seminal vesicles
A
● Secrete mucus, fructose sugar (which provides energy for the sperm) and the hormone prostaglandin during sexual intercourse
11
Q
~Prostaglandin
A
● Stimulates uterine contractions
12
Q
~Seminiferous tubules
A
● Sites of sperm formation int he testes
13
Q
~Sertoli cells
A
● Provide nutrients for developing sperm
14
Q
~Testes/testis
A
● Male gonads, where sperm are produced
15
Q
~Urethra
A
● Tube that carries semen and urine
16
Q
~Vas dferens
A
● Muscular duct that carries sperm during ejaculation from the epididymis to the urethra in the penis
17
Q
~Ovaries
A
● Where meiosis occurs
18
Q
~Oviducts/Fallopian tubes
A
● Where fertilization occurs
● After ovulation, the egg moves through the oviduct to the uterus
19
Q
~Uterus
A
● Where blastocyst will implant and where the embryo will develop during the nine-month gestation if fertilization occurs
20
Q
~Endometrium
A
● Lining of the uterus that thickens monthly in preparation for implantation of the blastocyst
21
Q
~Vagina
A
● Birth canal
● During labor and delivery, the baby passes through the cervix and into the vagina
22
Q
~Cervix
A
● The mouth of the uterus
23
Q
~Follicular phase
A
● Several follicles in the ovaries grow and secrete increasing amounts of estrogen in response to follicle-stimulating hormone (FSH) from the anterior pituitary
24
Q
~Ovulation
A
● Secondary oocyte ruptures out of the ovaries in response to luteinizing hormone
25
~Luteal phase
● Corpus luteun forms in response to luteinizing hormone
● It is the follicle left behind after ovulation and secretes estrogen and progesterone, hwich thicken the endometrium of the uterus
26
~Menstruation
● The monthly shedding of hte lining of the uterus when implantation of an embryo does not occur
27
~Positive feedback in the menstrual cycle
● Enahces a process until it is completed
● During the follicular phase, estrogen released from the follicle stimulates hte release of LH from the anterior pitruitary
● The increase in LH stimulates the follicle to release even more estrogen
● The hormone levels continue to rise until the follicle matures and ovulation occurs
28
~Negative feedback in the menstrual cycle
● Stops a process once homeostasis is reached
● During the luteal phase, LH stimulates the corpus luteum to secrete estrogen and progesterone
● Once the levels of estrogen and progesterone reach sufficiently high levels, they trigger the hypothalamus and pituitary to shut off, thereby inhibiting the secretion of LH and FSH
29
~Spermatogenesis
● Process of sperm production
| ● Contiuous process that starts at puberty
30
~Oogenesis
● Production of ova
● Begins prior to birth
● Within the embryo, an oogonium cell (2N)
- These remain quiescent within small follicles in the ovaries until puberty, when they become reactivated by hormones
● FSH periodically stimulates the follicles to complete meiosis I, producing secondary oocytes (N), which are released at ovulation
● Meiosis II then stops again and does not continue until fertilization, when a sperm penetrates the secondary oocyte
31
~Fertilization
● Fusion of pserm and ovum nucleic
● Begins with the acrosome reaction
● Specific recognition
32
~Acrosome reaction
● The head of the sperm (acrosome) releases hydrolytic enzymes that penetrate the jelly coat of the egg
● Specific molecules from the sperm bind with receptor molecules on the vitelline membrane before the sperm come in contact with the ovum's plasma membrane
33
~Specific recognition
● Ensures that the egg will be fertilized by only sperm from the same species
34
~Fast block to polyspermy
● Lasts only a minute but just long enough to allow the slow block to polyspermy
● Once a sperm binds to receptors ont he egg, the membrane is dramatically depolarized and no other sperm can penetrate the egg membrane
35
~Slow block to polyspermy
● Converts the vitelline membrane into an impenetrable fertilization envelope
36
~8Parthenogenesis
● Development of an unfertilized egg
● An unfertilized egg can be activated artificially by electrical stiulation or by injection with Ca ions
● Resultin adult is haploid
37
~Drone honeybees
● Develop by natural parthenogensis from unferilized eggs and are haploid males
38
~Embryonic devel[opment
● Consists of three stages: cleavage, gastrrulation and organogenesis
39
~Sea urchin egg
● Eggs with almost no yolk
| ● Typical embryonic development
40
~Frog egg
● In eggs with more yok, such as those of the frog, cleavage is unequal, with very little cell division in the tyoky region
41
~Bird egg
● In eggs with a great deal of yolk, such as a bird egg, cleavages is limited to a small, nonyolky disc at the top of the egg
42
~Cleavage
● Rapid mitotic cell division of the zygote that occurs immediately after fertilization
● Produces a fluid-filled ball of cells caleld a blastula
● Embryo at this stage is called a blastocyst in mammals
● Clustered at one end of the blastocoel cavity is a group of cells called the inner cell mass
43
~Inner cell mass
● Will develop into the embryo
44
~Pluripotent
● THe cells of the very early blastocoel stage are pluripotent
● Are the source of embryonic stem cell lines
45
~Trophoblast
● The cells that surround the inner cell mass
| ● Secrete fluid, creating the blastocoe., and also form sturcutres that will atach the embryo to the mother's uterus
46
~Differentiation
● THe cells of the blastocyst or balstula communicate with each other and begin to differentiate
● In many animals, the movement of the cells is so regular that it is possible to leabel a specific blastomere (individiaul cells of a blastocyst) and identify the tissue that results as embryonic development proceeds
- Produces a fate map
47
~Gastrulation
● Process that involves rearrangement of the blastula or blastocyst and begins with the formation of the blastopore, an opening into the blastula
- In some animals, the blastopore become shte mouth, in others (deuterostomes), the blastopore becomes the anus
48
~Archenteron/primitive gu
● Some of the cells on the surface of the embryo migrate into the blastopore to form a new cavity
● As a result of this cell movement, gastrulation froms a three-layered embryo
49
~Gastrulation
● The three embryonic germ layered embryo formed by gastrulation
● Includes ectoderm, endoderm, and mesoderm
50
~Ectoderm
● Will become the skin and the nervous system
51
~Endoderm
● Will form the viscera including the lungs, liver, and digestive organs, and so on
52
~Mesoderm
● Will give rise to the muscle, blood, and bones
| ● Some primitive animals (sponges and cnidarians) develop a noncellular layer, the mesoglea, instead of the mesoderm
53
~Organogenesis
● Organ building
● Process by which cells continue to differentiate, producing organs from the three embryonic germ layers
● Three kinds of morphogenetic changes--folds, splitsn and dense clustering called condensation--are the first evidence of organ building
● Once all the organ systems have been developed, the embryo simply increases in size
54
~Fertilization in frog embryo
● Eggs are laid directly into water and fertilization is external
● When the sperm penetrates the egg, the pigementaed cap rotates toward hte point of penetration and a gray crescent appears
● Animal-vegetal asymetry dictates where the anterior-posterior axis forms in the embryo
55
~Vegetal pole
● One third of the frog egg is yolk, which is massed in the lower portion of the egg called vegetal pole
56
~Animal pole
● The top half is called animal pole and has a pigmented cap
57
~Gray crescent
● Appears ont he side opposite the point of entry of hte sperm
● Marker of the future doral side and is critical to normal dvelopment of hte growing embryo
58
~Cleavage and gastrulation in frog embryo
● Because of the presence of yolk, cleavage is uneven
● The blastopore forms at the border of the gray crescent and the vegetal pole
● Involution occurs
● A ectoderm cells stream inward by what is called epibolic movement, the blastocoel disappears and is replaced by another cavity called the archenteron
59
~Involution
● Cells at the dorsal lip above the blastopore begin to stream over the dorsal lip and into the blastopore
60
~Drorsal mesoderm
● THe region of mesoderm lining the archenteron that formed opposite the blastopore is caleld dorsal mesoderm
61
~Organogenesis in frog embryo
● In chordates, the organs to form first are the notochord and the neural tube
● Both notochord and neural tube form by embryonic induction
● After the blueprints of the organs are laid down, the embryo develops into a larval stage, the tadpole
● Metamorphisis will transofmr the tadpole into a frog
62
~Notochord
● The skeletal rod characteristic of all chordate embryo
63
~Neural tube
● Which will become the central nervous system
| ● Forms from the dorsal ectoderm just above the notochord
64
~Cleavage and gastrulation in bird enbryo
● The bird's egg has so much yolk that development of the embryo occurs in a flast disc of blastodisc that sits on top of the yolk
● A primitive streak forms instead of a gray crescent
● Cells migrate over the primitive streak and flow inward to form the archenteron
● As cleavage and gastrualtion occur, the yolk gets smaller
65
~Extraembryonic membranes
● Tissue outsid the embryo forms four extraembryonic memrbanes necessary to support hte growing embryo inside the shell
● THey are the yolk sac, amnion, chorion and allantois
66
~Yolk sac
● Encloses the yolk, food for the growing embryo
67
~Amnion
● Encloses the embryo in protective amniotic fluid
68
~Chorion
● Lies under the shell and allows for the diffusion of respiratory gases between the outside and the growing embryo
69
~Allantois
● Analogous to the placenta in mammals
● COnduit for respiratory gases between the environment and the embryo
● Also the repository for uric acid, the nitrogenous waste from the embryo that accumulates until the chick hatches
70
~Cytoplasmic determinants
● The dissection of eight-ball embryo demonstrates that hte cytoplasm surrounding the nucleus has profound effects on embryonic development
● The importance of the cytoplasm in the development of hte embryo is known as cytoplasmic determinants
71
~Hans Spemann
● Demonstrated the importance of the cytoplasm associated with the gray crescnet in the normal development of the animal
● He dissected embryos in the two-ball stage in different ways
- Only the cell containing the gray crescent developed normally
72
~Embryonic induction
● The ability of one group of embryonic cells to influence hte development of another group of embryonic cells
● Spemann proved that hte dorsal lip of the blastopore normally initiates a chain of inductions that results in the formation of a neural tube
73
~Apoptosis
● Programed cell death
● Many more neurons are produced during development of the vertebrate nervous system thatn exist in teha dult
- This is because neruons survive if they make connections iwth other neurons during developemtna nd self-destruct if they do not
74
~Webbing
● During early embryonic development, it connects hte spaces between fingers and toes
● As developmetn proceeds, cells that make up the webbing undergo apoptosis
● The webbing is eliminated and the fingers and toes can separatej
● Sometimes a human baby is born with some residual webing, the result of incomplete embryonic development
75
~Homeotic/homeobox/hox genes
● Master regulatory genes that control the expression of genes that regulate hte placement of specific anatomical structures
● Play a critical role in normal embryonic development
76
~What advantagaes do asexual reproductions have over sexual reproductions?
● Enable animals living in isolation to reproduce without a mate
● Can create numerous offsrping quickly
● No expenditure of energy-maintaing reproductive systems or hormonal cycles
● Because offspring are clones of the parent, it is advantageous hwen the environment is stable
77
~What advantages do sexual reproductions have over asexual reproductions?
● Genetic variation
| ● May be better able to survive than either parent, especially in an environment that is changing
78
~What does the human male reproductive system include?
```
● Epididymis
● Leydig cells
● Prostate gland
● Scrotum
● Seminal vesicles
● Seminiferous tubules
● Sertoli cells
● Testes
● Urethra
● Vas deferens
```
79
~What does the human female reproductive system include?
```
● Ovaries
● Oviducts/Fallopian tubes
● Uterus
● Endometrium
● Vagina
```
80
~What are the four phases in menstrual cycle?
● Follicular phase
● Ovulation
● Luteal phase
● Menstruation
81
~What stimulates the beginning of pserm production?
● Begins as LH induces the interstitial cells of the testes to produce testosterone
● Together with FSH, tetosterone induces maturation of the seminiferous tubules and stimulates the beginning of sperm production
82
~What happens in Spermatogenesis?
● In the seminiferous tubules, each spermatogonium cell (2N) divdies by mitosis to produce two primary spermatocytes (2N)
- Each undergoes meiosis I to produce two secondary spermatocytes (N)
- Each secondary spermatocyte then undergoes meiosis II, which yields 4 spermatids (N)
● These spermatids differentiate and move to the epididymis where they become motiel
83
~How does oogenesis differ from sperm formation?
1. Stop-start process
● It begins prior to birth and is completed after fertilization
2. Cytokinesis divides the cytoplasm of the cell unequally, producing one large cell and two small poar bodies which will disintegrate
3. One primary oogonium cell gproduces only one active egg cell
84
What is the future development of the two halves of embryo depended on?
● Plane in which they are cut
● If the dissection is longtudinal, producing embryos containing cell sfrom both animals and vegetal poles, subsequent development is normal
● If the plant fo dissection is horizontal, the result is four abnromally developing embryo
85
~What was Spemann's experient that proved the dorsal lip of the blastopore normally initiates a chain of inductions htat results in the formation of a neural tube?
● He grafted a pice of dorsal lip from one amphibian embryo onto the entral side of a second amphibian embryo
● What developed on the recipient was a complete secondary embryo attached at the site of the graft
● THe dorsal lip induced the abdomen tissue above it to become neural tissue
86
~What did Spemann name the dorsal lip and why?
● Because it plays a crucial role in development, Spemann named hte dorsal lip the primary embryonic organizer or simply the organizer
● Scientists now have identified that the protein beta-catenin is a likely candidate for the transcription factor that triggers which cells become the organizers
