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Repro. Med 1 > Fetal Embryology > Flashcards

Fetal Embryology Flashcards

1
Q

Urogenital anatomy begins to develop at what week developmentally?

A

~ wk 4

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2
Q

Development of a ______ ______, occurs first in the fetus, which forms along dorsal aspect of _____ ____ (body cavity, lined w/ ______), Posterioolateral to the vertebral region.

A

Urogenital Ridge

coelomic cavity

mesoderm

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3
Q

There are three regions of the urogenital ridge, the _____ region, a ____ region, and a ____ region

A

pronephric region

mesonephric region

metanephric region

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4
Q

At 3 wks, a _______ forms in the cervical region of embryo, which functions [very minimally] as the ______.

It then differentiates into one ___ on each side

A

pronephros

kidney

long nephron

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5
Q

By 4-4.5 wks, the embryo needs more filtration, and so the pronephros dies off by ______ as the _______ takes over, which forms in the _______ region and develops from (inferior/superior to inferior/superior).

A

apoptosis

mesonephros

upper thoracic-upper lumbar

Superior to inferior

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6
Q

The mesonephros performs filtration from _____ wks gestation, with (all/not all) parts at once

A

~4-10 weeks

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7
Q

At 4-5 wks, mesonephros filtration is replaced by the ______, which becomes the adult kidney, and part to all (depending on hormones present) of the mesonephric ducts are reabsorbed via ______.

A

metanephros

apoptosis

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8
Q

The metanephros begins to form at wk ___ and becomes functional around wks ____

A

5

9-10

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9
Q

Gonads begin to form during wks ____, which is considered the “_____ stage” because sex is not yet [genotypically/phenotypically] obvious.

A

5-6

indifferent; phenotypically

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10
Q

______ and ______ ducts are destined to be gonads

A

mesonephric

paramesonephric

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11
Q

Gonads (testes and ovaries) develop from a thickening of the ______ surface of the _______, called the gonadal ridge.

A

ventromedial

gonadal ridge

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12
Q

When and where do primordial germ cells (PGCs) differentiate?

A

In the neck of the yolk sac early in the 4th week

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13
Q

PGCs migrate to the _____ via a process called “____ ____”

A

genital ridge

amoeboid movement

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14
Q

By end of ____ wk, the PGC become incorporated into the primary sex cords/gonads via diapedesis through the _______ (otherwise known as the _____ duct), which causes the ____ to grow

A

6th

umbilical cord

vitelline

gonads

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15
Q

In developement of genital ducts __ weeks is the ____ stage

B/c Both male and female genital ducts are present

A

<10

Indifferent

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16
Q

Male duct system develops from the _____

Mesonephric ducts form ___, ___, ___, ___

A

mesonephric/wolffian ducts

epididymis

ductus deferens

efferent ducts

ejaculatory duct

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17
Q

Female duct system dev. from the ____

Paramesonephric ducts form ___, ____, ____

A

paramesonephric/mullerian duct

fallopian tubes

uterus

upper ⅔ of the vagina

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18
Q

Development of the genital ducts Begins during the ___ month of gestation or __-__ wks

From here, much depends on the presence or absence of a __ chromosome, specifically, the presence of the ___ region of the this chromosome

A

3rd

8-9

Y

sex-determining (SR-Y)

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19
Q

SR-Y codes for a protein called ___

This protein causes ___ ducts to differentiate into male genital structures, the gonads to become testes, & testes make ____→ Mullerian (paramesonephric) ducts to regress

A

TDF (testis determining factor)

Wolffian (mesonephric)

Mullerian Inhibiting substance

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20
Q

W/o an SR-Y region, there is no ___ → ___ ducts regress, gonads become ovaries, and there is no ____ → the Mullerian ducts develop into female internal genitalia

A

TDF

Wolffian

mullerian inhibiting substance

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21
Q

____ are Primary sex cords of testes containing primordial germ cells.

They are well-defined cords w/in the ___ of the testis

A

testes cords (spermatic cords)

medulla (middle)

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22
Q

The Testes cords (spermatic cords) contain two types of cells:

____, _____

A

Epithelial cells

Primordial germ cells

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23
Q

Epithelial cells become_____

Primordial germ cells become____

A

Sertoli cells (nurse cells for developing sperm)

Spermatoblasts

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24
Q

The spermatic cords remain ____ until puberty

They then ____ to form ____

A

solid

canalize

seminiferous tubules (ST)

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25
Q

Seminiferous tubules are separated from each other by ___, giving rise to____, which make ____

A

mesenchyme

interstitial cells (cells of Leydig)

testosterone

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26
Q

Fetal testes produce ___ whi

Stimulate dev. of the ____, Suppress formation of the ___

A

androgens

mesonephric (Wolffian) ducts

paramesonephric (Mullerian) ducts

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27
Q

If the testes fail to develop in the fetus, or are removed from the fetus early on, ____ will develop into female internal genitalia

If ovaries fail to develop or are removed in the female fetus, there (Is/Is no) effect on fetal sexual development

A

paramesonephric ducts

IS NO

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28
Q

A __ is a common opening shared by the digestive/reproductive/urinary tracts

Humans this develops in utero, but it becomes divided by __ of gestation

A

cloaca

wk 7

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29
Q

Cloacal separation In the indifferent stage:

___ develops at anterior end of cloacal membrane, it slongates eo form the ___

____ swellings and _____ folds appear

A

Genital tubercle

phallus (gonad)

Labioscrotal, Urogenital

30
Q

In male external genitalia, the ___ elongates to form the penis

Elongation pulls the urogenital folds together

Folds fuse to enclose the urethra, urethral opening moves towards (end/bottom) of penis

A

Phallus

Bottom

31
Q

Labioscrotal swellings meet ___ and fuse, forming scrotum

labioscrotal folds move inferior to the urogenital sinus and then fuse→ urogenital folds do the same

Fusion of the urogenital folds creates the ___ and the ____

A

posteromedially

penis, elongated urethra

32
Q

____ is Incomplete fusion of urethral folds→ typically more distal

A

Hypospadias

33
Q

Descent of the testes occurs due to the pulll from the ____ & tethers the testes in the scrotum.

Descent of the testes to the level of the internal inguinal ring occurs __ month gestation.

A

gubernaculum shortening

~ 7

34
Q

Gonadal development occurs (Fast/Slow) in females

Until ____, the ovary cannot be identified histologically

A

SLOW

wk 10

35
Q

___ carry the genes for ovarian development

___ genes also appear to play a role in ovarian development

A

X chromosomes

Autosomal

36
Q

Early fetal period: Cords of ____ (sex cords) extend from surface epithelium of the developing gonad into the underlying mesenchyme (think surface area).

The ___ comes from mesodermal tissue

(pertains to ovarian development)

Sex cords ↑ in size & ____ cells are incorporated into them

___ weeks: those cords begin to break up, forming ____

A

Cortical tissue

Epithelium

primordial germ

~16

primordial follicles

37
Q

Primordial Follicles consists of ___ & ____

A

Oogonium: from a primordial germ cell

Follicular Cells: from surface epithelium and surround oogonium as a layer of flattened cells

38
Q

Active ___ of the oogonia occurs during fetal life, producing millions of primordial follicles ~20 wks

(No/more) oogonia form postnatally→ all are formed prior to birth

~2 million remain to become primary oocytes at time of birth; by puberty ~ ____ remain

A

mitosis

NO

½ million remain

39
Q

In female embryos, the mesonephric ducts regress in the absence of ___

Female sexual development (does/does not) depend on the presence of ovaries or hormones→ just on the absence of MIS, which is coded for in the SR-Y region

A

testosterone

Does not

40
Q

Both of the paramesonephric ducts pass caudally and reach the future pelvic region

They cross-over (anterior/posterior) to the mesonephric ducts to meet at the midline in the pelvic region and fuse to form a _____ in the midline

This tubular structure projects into dorsal wall of urogenital sinus, will become the____ and ____

A

Anterior

Y-shaped uterovaginal primordium

uterus & superior part of vagina

41
Q

From where do the Fallopian tubes develop

A

develop from the unfused, cranial part of the paramesonephric ducts

42
Q

Endometrial stroma (structural, non-glandular part of the endometrium) and myometrium are derived from a special subset of mesodermal cells called ____ (also found in heart & kidneys)

A

splanchnic mesenchyme

43
Q

When paramesonephric ducts fuse, the process also brings together two sides of a peritoneal fold that, when folded together, form the ___.

The process also forms two peritoneal compartments: ___ and ____

A

broad ligament

Rectouterine pouch

Vesicouterine pouch

44
Q

Enlargement at end of uterovaginal primordium induces formation of paired endodermal outgrowths called ___, which fuse to form a ___ → later, central cells of vaginal plate break down, forming the ____

A

sinovaginal bulbs

vaginal plate

vaginal lumen

45
Q

At the most caudal part of uterovaginal canal, the sinovaginal bulbs meet w/ urogenital sinus; the urogenital sinus inverts, and moves into the pelvic cavity to meet the sinovaginal bulbs→ the 2 sets of tissue fuse and canalize, forming the _____.

A

vagina

46
Q

The ____ is formed by invagination of the posterior wall of urogenital sinus, resulting from expansion of caudal end of the vagina

A

Hymen

47
Q

What hormone from placenta & fetal ovaries are involved in feminization of external genitalia?

A

Estrogen

48
Q

In females the Phallus grows but remains small, becoming the ___

A

clitoris

49
Q

Clitoris is relatively large at 18 wks→ it develops like a penis, but the urogenital folds only fuse just posterior to the glans to form the frenulum of the ___→ the unfused parts of the urogenital folds form the ____

A

labia minora

labia minora

50
Q

Labioscrotal folds fuse posteriorly to form the ____ and fuse anteriorly to form anterior___ and ____

A

posterior labial commissure

labial commissure and mons pubis

51
Q

Most parts of the labioscrotal folds remain unfused and form 2 large folds of skin called ____ (homologous to the ___)

A

labia majora

52
Q

Describe the structure of Steroids and how they are distinguished from each other , derived from cholesterol & closely related

A

4-ring structure of carbon atoms

by their side chains

53
Q

What are steroids derived from and where are they made?

A

cholesterol & closely related

Ovaries

Testes

adrenal glands

54
Q

What are the 3 steroid hormones

A

Testosterone

Estrogen

Progesterone

55
Q

____ is an active steroid hormone & an important intermediary

A

Progesterone

56
Q

_______ is Cortisol deficiency (sometimes Aldosterone) occurs, causing fetal pituitary to make more ACTH, causing cortisol to be made but much more androgen is made as well

A

Congenital Adrenal Hyperplasia (CAH)

57
Q

90%+ of the time, CAH is due to ______ deficiency in a developing fetus

A

21α-hydroxylase

58
Q

In Congenital Adrenal Hyperplasia (CAH) what happens to the Adrenals how does this impact the hormones being produced?

how does this impact the female and male genitalia

A

They enlarge because of the cortisol precursor they make

Normally, the adrenal cortex makes a small amount of testosterone→ in this case, testosterone is drastically ↑

Females appear significantly different phenotypically, males will appear the same

59
Q

What is the test for CAH

A

check their serum and urine for elevated 17-OHP (precursor to 21a-hydroxylase)

60
Q

T/F Congenital Adrenal Hyperplasia (CAH) → is an EMERGENCY

A

True

61
Q

The genital tubercle becomes the ____ in females and the ____ in males

A

F = clitoral glans

M= glans penis

62
Q

the Urogenital folds become the ____ in females and the ____ in males

A

F= vuval and labial openings

M = Phallic shaft

63
Q

the scrotum in men are homologu to the ___ in females

A

Labia majora

64
Q

the fore skin on men is homologus to the ___ and ____ in females

A

labia minora

clitoral hood

65
Q

Estrogen controls dev.of ____ and promotes _____ development

In females, estrogen is produced by the ____

A

2° sex characteristics

normal bone

developing follicles of the ovaries

66
Q

Estrogen variants

A

Estradiol (E2)

Estrone (E1)

Estriol (E3)

67
Q

_____Less-active form of estrogen; created in ↓lvls in fat cells when steroids are stored there

A

Estrone (E1):

68
Q

____ Much less active form→ created in small amounts in the liver; created in ↑ amounts in placenta; can be used as a marker for Neural Tube Defects

A

Estriol (E3):

69
Q

____ is a Major form of estrogen made by ovaries; most hormonally-active

A

Estradiol (E2):

70
Q

Peripheral Hormone Conversions of estrogen occur in the presence of ___

A

Aromatase

71
Q

Only___, ___ steroid hormone can participate in enzymatic rxns

A

free, unbound

72
Q

Estrogen target tissues include:

A

Brain (hypothalamic/pituitary)

CV

mammary gland

liver

reproductive tract (uterus/cervix/vagina/ovary/testes/prostate)

bone

Repro. Med 1 (9 decks)

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