Lecture 25 3/19/24 Flashcards

1
Q

What is the gonadal ridge?

A

undifferentiated primitive gonad during early embryonic development

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2
Q

What are the paramesonephric ducts?

A

part of a primitive kidney system during embryonic development

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3
Q

What is the yolk sac?

A

evolutionary remnant in mammals that still has functions in early embryonic development

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4
Q

What is the allantois?

A

part of the placenta involved in the formation of the umbilical cord and the exchange of nutrients/gas/metabolites

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5
Q

What are the characteristics of the primordial germ cells?

A

-migrate from the yolk sac to the gonadal ridge
-populate sex cords/cortical region of embryonic gonads
-become sperm or oocytes

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6
Q

What is the pronephros?

A

nonfunctional remnant of primitive kidney

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7
Q

What are the characteristics of the mesonephros?

A

-bilateral pair of intermediate kidneys
-replace the pronephros
-produce urine
-drained by the mesonephric ducts

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8
Q

What are the characteristics of the metanephros?

A

-final renal form
-develop functional nephrons
-functional form of kidney in the adult

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9
Q

What is the sexually indifferent stage?

A

when both the mesonephric and paramesonephric ducts are present, but the embryo is still undifferentiated in terms of sex

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10
Q

What is a true hermaphrodite?

A

individual with ovotestes or one ovary and one testis

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11
Q

What is a pseudohermaphrodite?

A

individual in which the gonads are consistent with the chromosomal sex, but the external genitalia is the opposite

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12
Q

Which substance controls the pathway towards being male or female?

A

testis determining factor/sex-determining region in the Y chromosome

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13
Q

How does testis determining factor (TDF) lead to a male individual?

A

-induces testicular development and differentiation of Sertoli cells
-Sertoli cells produce AMH (anti-Mullerian hormone)
-AMH induces Leydig cell differentiation and paramesonephric duct degeneration
-Leydig cells produce testosterone and DHT, leading to male duct system development

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14
Q

How does a lack of TDF lead to a female individual?

A

-absence of TDF allows gonads to develop into ovaries
-paramesonephric ducts give rise to female repro. tract

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15
Q

Which ducts are utilized in the male vs female?

A

male: mesonephric
female: paramesonephric

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16
Q

Which follicles form the cortex of the ovary?

A

primordial follicles

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17
Q

What are the characteristics of granulosa cells?

A

-surround gametes
-originate in sex cords

18
Q

What are the characteristics of theca cells?

A

-form outer layer of follicles
-originate in gonadal ridge

19
Q

How do the paramesonephric ducts give rise to the female repro tract?

A

-cranial part of duct develops into infundibulum
-uterus, cervix, and cranial vagina develop from fusion of the lower portion of the ducts

20
Q

How do the mesonephric tubes play into the male repro tract?

A

-seminiferous tubules connect to rete testis and mesonephric tubes
-efferent ducts are derived from mesonephric tubes and give rise to epididymis and ductus deferens

21
Q

What is the function of the gubernaculum?

A

-regression of the gubernaculum moves the testes into the scrotum
-remnant of the gubernaculum attaches testes to the bottom of the scrotum

22
Q

When does testicular descent complete?

A

-before or around parturition in most species
-between days 3-45 of life for dogs
-movement between scrotum and inguinal canal until 2-4 months in cats

23
Q

What is cryptorchidism?

A

failure of the testes to descend

24
Q

What is inguinal herniation?

A

when a portion of intestine passes into the vaginal cavity and enters the scrotum

25
Q

What are the characteristics of the pineal gland?

A

-involved in sleep patterns, circadian rhythms, and seasonal cycles
-produces melatonin

26
Q

What are the characteristics of the hypothalamus?

A

-regulates metabolic processes of the ANS
-produces and secretes releasing hormones that act on pituitary gland
-main repro. hormone is GnRH

27
Q

What are the repro. products of the pituitary gland?

A

-follicle stimulating hormone/FSH
-luteinizing hormone/LH

28
Q

What is the function of the tonic center?

A

spontaneous, rhythmic basal secretion of GnRH

29
Q

What are the characteristics of the surge center?

A

-responsible for preovulatory release of GnRH that stimulates LH and leads to ovulation
-releases basal levels of GnRH until appropriate stimulus is present

30
Q

What is the stimulus for the surge center?

A

threshold level of estrogen in the absence of progesterone

31
Q

Why do males only have a tonic center, and not a surge center?

A

testosterone from the fetal testis “defeminizes” the brain during development once it crosses the BBB and is converted into estrogen

32
Q

Why does estrogen not defeminize the brain in females during development?

A

-estrogen produced by the ovaries binds to alpha fetoprotein (AFP)
-estrogen bound to AFP is too large to cross the BBB and act on the hypothalamus

33
Q

What is the function of FSH?

A

responsible for growth and development of follicles during follicular phase

34
Q

What is the function of LH?

A

responsible for ovulation

35
Q

What is the positive feedback loop that acts on the female repro tract?

A

-FSH causes follicles to grow and mature
-granulosa cells in the follicle produce increasing concentrations of estradiol as they grow
-estradiol stimulates surge center to release GnRH, leading to LH secretion

36
Q

What are the negative feedback loops that act on the female repro tract?

A

-presence of large quantities of estradiol inhibits further secretion of FSH
-presence of progesterone inhibits GnRH neurons

37
Q

What are the processes associated with antral follicles?

A

-recruitment
-selection
-dominance
-atresia

38
Q

What are the characteristics of recruitment?

A

-small follicles
-low estradiol
-high FSH and low LH

39
Q

What are the characteristics of selection?

A

-medium follicles
-medium estradiol, inhibin
-decreased FSH, increasing LH

40
Q

What are the characteristics of dominance?

A

-large follicle
-surge center
-high estradiol, inhibin
-high LH

41
Q

Which negative feedback loop acts on the male repro tract?

A

testosterone inhibits both hypothalamus and pituitary gland