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REPRO > Fish and reptile reproduction > Flashcards

Fish and reptile reproduction Flashcards

1
Q

Where are the gonads located in snakes?

A

Near gall bladder

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2
Q

Where are the gonads in most reptiles?

A

Near cranial pole of kidney

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3
Q

What determines onset of sexual maturity in reptiles?

A

Size (and so is linked with diet)

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4
Q

Describe the male reproductive anatomy in reptiles

A
  • Intra-abdominal testes (right cranial to left)
  • No accessory sex glands
  • Phallus fibrocollagenous elastic erectile tissue
  • Single or 2 hemipenes
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5
Q

What species of reptiles have a single penis?

A

Chelonians

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6
Q

What species of reptiles have 2 hemipenes?

A
  • Lizards

- Snakes

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7
Q

Describe squamate hemipenes

A
  • Paired, kept in tail base by retractor penis muscle
  • In copulation evert hemipenis on one side
  • Erection is vascular
  • Sherp keratinised spines or flounces on surface
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8
Q

Describe the sexual segments

A
  • In distal convoluted tubules of kidney
  • Only actively present in breeding season
  • Cuboidal to columnar cell change
  • Large eosinophilic granules secreted into lumen
  • Function unknown, amy be to separate urine and semen for copulation or form copulatory plug
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9
Q

Describe female reptile anatomy

A
  • Ovaries paired in most
  • Snake: elongated ovaries (some missing left oviduct)
  • No true uterus
  • Oviducts into cloaca: genital papillae
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10
Q

What is the function of the oviducts in reptiles?

A

Secrete albumin to produce the shell

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11
Q

What are the elements of the oviducts in reptiles?

A
  • Not all elements in all species
  • Infundibulum
  • Uterine tube
  • Isthmus
  • Uterus/shell gland
  • Vagina
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12
Q

What is a vitellogenic follicle in reptiles?

A

One that is close to ovulation

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13
Q

Describe intersexuality in reptiles

A
  • Can be either true males/females or intersex (hermaphrodites)
  • Females with hemipenes
  • +/- ovotestes
  • e.g. pit viper, all pregnant animals are intersex
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14
Q

Describe parthenogenesis in reptiles

A
  • 30 species of lizards (incl. komodo, gecko, whiptail)
  • No mating
  • Chormosomes in unfertilised egg replicate in egg
  • Embryo develops
  • Females still display courting and pseudocopulation
  • Some species use sexual and asexual reproduction
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15
Q

Describe male reproductive anatomy in fish

A
  • Paired intra-abdominal testes

- Testicular duct (not salmonids)

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16
Q

What is the function of the testicular duct in fish?

A

Carries sperm outside body

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17
Q

How are sperm released by salmonids?

A
  • Released into body cavity

- Then released by pores

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18
Q

What are the 2 types of female reproductive anatomy found in fish?

A
  • Gymnovarian

- Cystovarian

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19
Q

Describe gymnovarian

A

Oocytes in coelom to oviduct funnel remants rather than via tube

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20
Q

Describe cystovarian

A

Ovarian ducts (not oviducts) grow posteriorly to form new ducts, oviducts regress and not present in adult form

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21
Q

How do the ovarian ducts of cystovarians form?

A

Peritoneal folds wrapped around each ovary

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22
Q

List the stages of reproduction in reptiles

A
  • Oocyte development
  • Vitellogenesis
  • Oocyte maturation
  • Ovulation
  • Fertilisation
  • Oviposition/parturition
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23
Q

Describe oocyte development in reptiles

A
  • Majority of reprocdution

- Pre-vitellogqenic follicle developmentq

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24
Q

Describe vitellogenesis in reptile reproduction

A
  • Yolk production

- Yolk proteins made in liver, deposited in developing oocyte in ovary

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25
Q

Describe fertilisation in reptiles

A
  • Cranial oviduct
  • Sperm viable at body temperature
  • Sperm from multiple males can be stored hence can have multiple matings
  • Higher fertility when bred in active cycle
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26
Q

How long can sperm be stored in reptiles?

A

Up to 6 years, so fertilisation can occur years after contact with male

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27
Q

Define oviparous

A

Egg laying

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28
Q

Define viviparous

A

Live bearing, can be lecithotrophy or matrotrophy

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29
Q

Define lecithotrophy

A

Egg in tract until hatching (nutrients mostly from yolk, hatch at time of parturition)

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30
Q

Define matrotrophy

A

Live bearing, chorioallantoic placenta (nutrients from mother)

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31
Q

What are the disadvantages of viviparity?

A
  • Foetus takes up space limiting GI tract function
  • Greater drain on maternal resources
  • One clutch/year vs oviparous >1
32
Q

What are the advantages of viviparity?

A
  • Common in cold climates as keeps embryos warm during incubation
  • higher chance of offspring survival
33
Q

How long is gestation in viviparous species approximately?

A

1.5-6 months

34
Q

Why is gestation hard to determine in reptiles?

A
  • Sperm storage, unsure of when fertilisation takes place

- Mating event not good way of determining fertilisation

35
Q

How long is incubation in oviparous species?

A

1-2 months typically, can be up to 270 days or more

36
Q

What is the role of FSH and LH in chelonians?

A
  • Similar to mammals
  • FSH: ovarian growth and follicular development
  • LH: surge stimulating ovulation
37
Q

What are the reproductive hormones present in squamates?

A
  • Only FSH-like compound (no LH)
  • Oestrogen
  • Progesterone
38
Q

What is the role of oestrogen in reptiles?

A
  • Yolk development

- Seasonal breeders high in early season (vitellogenesis)

39
Q

Describe the role of progesterone in reptiles

A
  • Ovulation tiggered by progesterone surge in chelonians
  • Made by CL in those that have it
  • Inhibits oviduct contraction (preventing embryo expulsion)
  • In all seasonal breeders high after ovulation
  • High during gestation in viviparous species
40
Q

What reptilian species have a CL?

A
  • All viviparous

- Not all chelonians make progesterone

41
Q

List the stages of reproduction in fish

A
  • Oocyte development
  • Vitellogenesis
  • Oocyte maturation
  • Spawning
  • Recovery
42
Q

Describe oocyte development in fish

A
  • Gonadotrophin independent

- Body size dependent (affected by nutrition)

43
Q

Describe vitellogenesis in fish

A

Yolk production, is longest phase

44
Q

Describe oocyte maturation in fish

A

Requires prostaglandins

45
Q

Descrbe spawning in fish

A
  • Release eggs and sperm
  • Optimum environment for this is species dependent
  • Mating behaviour
46
Q

Describe post-spawing recovery in fish

A
  • Body condition restored

- New oocyte development

47
Q

Describe oviparity in fish

A
  • Most common (97% of fish)

- Most use external fertilisation

48
Q

Describe viviparity in fish

A
  • Fewer young produced
  • Internal fertilisation
  • Lectitrophy or matrotrophy
49
Q

Describe lecithotrophy in fish

A
  • Nutrition from yolk sac
  • Fertilised eggs stay in body of parent (majority)
  • Does not have to be female parent e.g. seahorses
50
Q

Describe matrotrophy in fish

A
  • Placenta like structure (very rare)

- Oophagy and intrauterine cannibalism common

51
Q

Describe reproductive endocrinology in fish in general

A
  • No hypophyseal portal system
  • GnRH to pituitary via direct innervation
  • Pituitary releases GTH-I and GTH-II
52
Q

What are the actions of GTH-I in female fish?

A
  • GTH-I: stimulates ovary to release gonadohormones

- Positive feedback effect on pit stimulating release of GTH-II

53
Q

What are the actions fo oestrogen and progesterone in female fish?

A
  • Oestrogen: vitellogenesis

- Progesterone: maintaining offspring in live bearers

54
Q

Explain how GTH-I carries out its action

A
  • Oogenesis
  • Stimulates release of gonadohormones
  • Binds to theca and granulosa cells in follicles
  • Testosterone production (theca) to E2 (granulosa)
  • E2 to liver to stimulate vitellogenin production
55
Q

Describe the actions fo GTH-II in the female fish

A
  • Oocyte maturation/ovulatioin

- Progestins from granulosa cells

56
Q

Describe the impact of season in reptile reproductioin

A
  • Temperature cahnge is stimulus for seasonality
  • Temperate spp.: spring after cooling period
  • Tropical boidae: cooler period breeding or year round
  • If rainfal is seasonal then rainfall is trigger
57
Q

Describe the environmental stimuli in reptile reproduction

A
  • Female primed by exposure to sexually mature male before mating (triggers egg prod)
  • Males exposed to females stimulates gonadal development and spermatogenesis
  • Humidity and barometric pressure
  • Photoperiod
58
Q

List the environmental factors affecting fish reproduction

A
  • Photoperiod
  • Temperature
  • Presence/absence of opposite sex
  • Currents, tides, stages of moon
  • Spawning area
59
Q

For the following chromosomal arrangements possible in reptiles, give the sex

a. ZZ
b. ZW
c. XX/XY
d. ZZ/ZW
e. ZWW
f. ZZZZ
g. ZZWW

A

a. male
b. female
c. male heteromorphic
d. female heteromorphic
e. female
f. male
g. female

60
Q

Explain how temperature affects sex determination

A
  • Affects enzyme activity
  • Appropriate tem for females, produce more aromatase, T converted to E2
  • Appropriate temp for males, produce more 5-alpha reductase (T converted to DHT)
61
Q

Describe sexual dimorphism in chelonians

A
  • Shell dimorphism
  • male concave plastron for mating
  • Tail dimorphism - male longer tail in some species
  • Vent more distal in males
62
Q

List sexing methods in squamates

A
  • Manual eversion of hemipenes
  • Hydrostatic eversion
  • Cloacal probing
  • Endocrinology
  • Ultrasonography
  • Endoscopy
63
Q

Describe the manual eversion of hemipenes method of sexing squamates

A
  • Not recommended
  • Roll thumb up base of tail towards cloaca
  • Pop out hemipene
  • Can cause injury
64
Q

Describe hydrostatic eversion of hemipenes in squamates

A
  • Inject saline just below hemipene
  • Increases pressure causing eversion
  • Not recommended as can cause injury
65
Q

Describe ultrasonography in sexing of squamates

A
  • Particularly if female with eggs

- Requires mature female to definitively say is female

66
Q

Describe cloacal probing for sexing of squamates

A
  • Instrument into inverted hemipene
  • Short distance = females
  • Long distance = male
  • Need to be experienced
  • Seminal plugs in males can give misleading results
67
Q

Describe blood endocrinology for sexing of squamates

A
  • Breeding season has higher hormone production

- Look for sex hormones

68
Q

Describe endocopy for sexing of squamates

A
  • Surgical
  • Anaesthetic risks
  • Potential for surgical complications
69
Q

What are the different reproductive models possible in fish?

A
  • Separate male and female
  • Hermaphodites
  • Parthenogenesis
70
Q

Describe fish sex determination

A
  • Genetic, present in 10% of fish
  • Male XY, female ZW
  • Some temperature depenedence
71
Q

List the types of reproductive cycles in reptiles

A
  • Continuous
  • Associated
  • Dissociated
72
Q

Describe continuous breeding in reptiles

A
  • Tropical zone
  • Throughout year
  • minimal photoperiod or temp fluctuation in place of origin, hence no advantage to being seasonal
73
Q

Describe associated reproductive cycles in reptiles

A
  • Subtropical or temperate zone
  • Male and female: gonadal/hormonal events coincide
  • Gonadal activity at time of mating
  • Long active season
  • Emergence from hibernation is trigger
74
Q

Describe dissociated reproductive cycles in reptiles

A
  • Some temperate zone
  • female and male reproductive events not linked
  • Gonadal activity does not coincide with mating
  • Short active season
  • Mate before gonadogenesis
  • Sperm used for fertilisation are from previous active season, produced in summer and stored in male over witner and used in next season
  • Female can also carry sperm until ovulation takes place
75
Q

List the different cycles of reproduction in fish

A
  • Can be 4 weeks to many years
  • Some continous spring and summer
  • Or once/year to many times a year
  • Or once in lifetime (pacific salmon)

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