Reproductive Embryology Flashcards

1
Q

What do the reproductive and urinary systems develop from?

A

mesoderm just lateral to the somites called intermediate mesoderm.

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2
Q

How do the mesonephric ducts form?

A

They form cranially to caudally and then fuse with the developing bladder

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3
Q

Where does the pronephros (first kidney) develop?

A

it develops in the cervical region and regresses (never functions)

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4
Q

Where does the mesonephros (middle kidney) develop?

A

in the thoracic to lumbar region (functions)

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5
Q

Where does the metanephros (third and definitive kideny) develop?

A

The mesonephric duct.

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6
Q

What are the the two parts of the metanephros?

A

The excretory system and the collecting system.

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7
Q

Where does the collecting system develop?

A

From the ureteric bud that sprouts from the mesonephric duct.

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8
Q

Where does the excretory system develop from?

A

Intermediate mesoderm cells that surround the ureteric bud, froming the metanephric blastema or metanephric mesenchyme.

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9
Q

What does the collecting system consist of?

A

The ureter, renal pelvic, calyces and 1-3 million collecting ducts.

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10
Q

What does the excretory system consist of?

A

nephrons, the functional unit of the kidney

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11
Q

What are nephrons?

A

They are vesicles or tubules that produce urine in the process of removing waste and excess substances from the blood.

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12
Q

What are glomeruli (capillary tufts)?

A

Capillaries that grow into the distal end of each nephron

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13
Q

How do kidneys shift due to the growth of the body?

A

cranially

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14
Q

What is a kidney that doesn’t completely ascend

A

pelvic kidney

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15
Q

what is a horeshoe kidney?

A

the fused kidneys ascend until caught under the IMA

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16
Q

What is bifed ureter or a double ureter?

A

the ureteric bud bifurcates before the metanephric blastema forms.

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17
Q

What is an ectopic kidney?

A

The kidney crosses to the other side during ascension

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18
Q

What is a thoracic kidney?

A

when the kidney ascends too far

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19
Q

What can congenital anomalies of the urinary system lead to?

A

urinary blockage, infection or kidney stones

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20
Q

What is multiple renal arteries?

A

The kidney is supplied by several arteries off the aorta during ascension, usually they degenerate. If these accesory renal arteries are damaged or ligated, part of the kidney can becomes ischemic.

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21
Q

When are the kidneys functional by?

A

The 12th week

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22
Q

How is fluid recycled through the kidneys?

A

urine is passed into amniotic cavity and mixes with amniotic fluid, fluid is swallowed by the fetus and recycles through the kidneys

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23
Q

What does bilateral renal agenesis result in?

A

oligohydraminos or insufficient amniotic fluid, causing compression of the fetus by the uterus.

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24
Q

What is potters sequence?

A

it results from oligohydraminos and results in limb deformities, wrinkly, dry skin; fascial anomalies (wide set eyes with infra-obrital skin creases, beak nose, recessed chin and low set ears); and pulmonary hypoplasia.

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25
Q

Where does the urinary bladder form from?

A

The caudal end of the hindgut (called the cloaca) when the urorectal septum (mesoderm) divides it into the urogenital sinus and the anorectal canal.

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26
Q

What does the urogenital sinus become?

A

The bladder and urethra

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27
Q

What does the allantois connect?

A

The apex of the bladder with the umbilicus.

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28
Q

What does the allantois become?

A

A fibrous cord called the urachus.

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29
Q

What is the urachus covered by and what does it become?

A

It is covered by peritoenum and becomes the median umbilical ligament on posterior aspect of the anterior abdominal wall.

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30
Q

What abnormalities can occur if the urorectal septum does not form correctly?

A

imperforate anus, urorectal fistula (an abnormal connect between the rectum and the bladder or the rectum and the urethra), and anal or anorectal agenesis.

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31
Q

What can persistence of a lumen in the urachus cause?

A

urachal fistula (urine can come out of the umbilicus), a urachal cyst, or a urachal sinus.

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32
Q

What does the reproductive system develop with?

A

The urinary system

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33
Q

What do primordial germ cells originate from? Where do they migrate and form?

A

They are originally from the epiblast, they migrate from the yolk sac into the intermediate mesoderm medial to the mesonephros causing formation of the gonadal ridge.

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34
Q

What does the epithelium covering the gonadal ridge do?

A

it is mesodermal in origin and it invades the underlying mesoderm to form the primitive or primary sex cords that surround the germ cells

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35
Q

By six week what is the embryo at in the reproductive development?

A

The indifferent stage

36
Q

What happens following the indifferent stage?

A

The reproductive system takes over early urinary structures as the indifferent gonads differentiate into the testes and ovaries.

37
Q

What do the mesonephric (Wolffian) ducts become?

A

The epididymis, vas deferens, and seminal vesicles.

38
Q

What do the paramesonephric (Mullerian) ducts become?

A

The uterus, uterine tubes, and upper vagina.

39
Q

When does sexual differentiation begin?

A

after the sixth week of development.

40
Q

What does the gonad develop into?

A

Either an ovary or testis.

41
Q

In the male what do primitive sex cords become?

A

testis cords

42
Q

In the male at the hilum, what do cord form?

A

The rete testis

43
Q

In the male, what do mesonephric tubules become?

A

efferent ducts

44
Q

In the male, what do mesonephric duct become?

A

epididymis, ductus deferens, and seminal vesicle

45
Q

In the female, what do primitive sex cords become?

A

somatic support cells and then follicle cells

46
Q

In the female, what do follicle cells surround

A

the PGCs (oogonia)

47
Q

What do the paramesonephric ducts become in a female?

A

the uterine tube, uterus, and upper vagina

48
Q

What do male accessory glands develop from?

A

Either endoderm or the mesonephric duct

49
Q

What do the prostate and bulbourethral glands bud off?

A

the urethra

50
Q

What do the seminal vesicles bud off?

A

the mesonephric duct

51
Q

What is the trigone?

A

the lower end of the mesonephric ducts are incorporated into the bladder to form the trigone. This results in the vas deferens wrapping over the ureter after the testes descend (bridge over troubled waters).

52
Q

When do the uterus and upper vagina form?

A

when the caudal ends of the paramesonephric ducts fuse.

53
Q

What are the remaining unfused paramesonephric ducts?

A

the uterine tubes.

54
Q

What does the lower vagina from from?

A

sinovaginal bulbs (proliferation of endodermal tissue on the posterior wall of urogenital sinus (future bladder and urethra).

55
Q

What do uterine and vaginal anomalies result from?

A

problems with development of the paramesonephric ducts.

56
Q

What is diethylstilbestrol (DES)?

A

a synthetic estrogen used to prevent miscarriage from 1947-71. it resulted in a higher risk of uterine anomalies and clear cell carcinoma of the vagina in offspring.

57
Q

What does the embryo have at the indifferent stage?

A

genital tubercle, urogenital folds, labioscrotal swellings, and anal folds

58
Q

In the female what does the genital tubercle become?

A

the clitoris

59
Q

in the female what do the urogenital folds form?

A

the labia minora

60
Q

in the female what do labioscrotal swellings form?

A

the labia majora

61
Q

in males what do urogenital fold form?

A

they fuse and genital tubercle elongates to become the shaft and glans of the penis.

62
Q

In males what does the urogenital (urethral) fold fusion form?

A

the penile urethra

63
Q

inWhat does the distal urethra form from in males?

A

the canalization of urethral endoderm extending into the glans.

64
Q

What do labioscrotal swellings fuse to form in males?

A

they fuse to form the scrotum.

65
Q

What are hypospadias?

A

occur when the urethral folds (another name for urogenital folds in the male) dont fuse completely (penile hypospadias) or form abnormal canalization of the urethral plate withing the glans penis (glans hypospadias).

66
Q

What are epispadias?

A

they occur when the urethral orifice opens into the dorsal suface of the penis (the anatomical position assumes the penis is erect); epispadias are usually associated with exstrophy of the bladder (the bladder is outside the ventral/anterior body wall due to a defect in the ventral body wall, i.e. it doesn’t form completely during body folding, this is very rare).

67
Q

Where are the gonads?

A

they form on the posterior body wall and must descend ot reach their usual anatomic position. They are attached cranially to the diaphragm by a suspensory ligament, and caudally to the labioscrotal swelling by a fibrous cord called gubernaculum.

68
Q

What is the gubernaculum?

A

a fibrous cord that connect the gonads caudally to the labioscrotal swelling

69
Q

What happens as the gonads descend?

A

the gubernaculum shortens, and an outpouching of parietal peritoenum, called the processus vaginalis (or vaginal process) is pushed along in front.

70
Q

What does the processus vaginalis form from?

A

the inguinal canal.

71
Q

What does the processus vaginalis close to become?

A

The tunica vaginalis.

72
Q

In the male, what do the layers of the abdominal wall pushed into the scotum by the processus vaginalis form?

A

three layers of the spermatic fascia in the spermatic cord.

73
Q

When do the testes reach the deep inguinal ring?

A

Around 4 months of embryonic development and descend through the inguinal canal shortly before (or right after) birth.

74
Q

What is cryptorchdism?

A

the testis fails to descend, it occurs in 1-4% of live male births and increases the risk for infertility and testicular cancer.

75
Q

What is the surgical correction of cyptorchidism?

A

orchipexy

76
Q

What is testicular tosion?

A

twisting of the spermatic cord that crimps the testicular artery.

77
Q

What is testicular hydrocele?

A

fluid between the parietal and visceral layers of the tunica vaginalis.

78
Q

What is an indirect (congenital) hernia?

A

protrusion of the perioteneal contents (mesentery, fat, bowel) through the inguinal canal. It represents 75% of inguinal hernias. Occurs lateral to the inferior epigastric vessels, passes through the deep inguinal ring and inguinal canal as a protrusion along the spermatic cord, and lies within the internal spermatic fascia.

79
Q

What do many indirect inguinal hernias arise from?

A

incomplete closure or weakness of the processus vaginalis. The herniated peritoneal contents may extends into the scrotum (or labia majora, but less common in females) if the processus vaginalis is patent along its entire course.

80
Q

Where do direct inguinal hernias pass through?

A

the inguinal triangles. They are more limited in the extent to which they can protrude through the ineromedial abdominal wall.

81
Q

How do direct inguinal hernias occur?

A

Because of an acquired weakness in the lower abdominal wall.

82
Q

Where can direct inguinal hernias exit?

A

at the superficial ring and acquire a lyaer of external spermatic fascia, they rarely herniate into the scrotum.

83
Q

Where do the ovaries descent into?

A

the pelvis but do not enter the labia majora.

84
Q

Where is the round ligament?

A

it transverses the inguinal canal into the labia majora (because it is the gubernaculum).

85
Q

How does the broad ligament form?

A

When the peritoneal folds covering the paramesonephric ducts fuse.

86
Q

What does the suspensory ligament of the ovary contain?

A

Ovarian vessels.

87
Q

What is the second pair of ducts that form lateral to the mesonephric ducts called?

A

paramesonephric ducts