embryo Flashcards
(154 cards)
1
Q
urinary system develops from
A
intermediate mesenchyme (primordial embryonic connective tissue consisting of mesenchymal cells)
2
Q
during horizontal folding of embryo, mesenchyme is carried
A
ventrally + loses connection with the somites
3
Q
longitudinal elevation of mesoderm is called the
A
urogenital ridge
4
Q
urogenital ridge forms
A
on both sides of the dorsal aorta
5
Q
part of urogenital ridge that gives rise to urinary system is called
A
the nephrogenic cord
6
Q
urinary system develops (before or after?) the genital system
A
before
7
Q
urinary system consists of the
A
kidneys, ureters, urinary bladder and urethra
8
Q
what are the 3 sets of successive overlapping kidney systems developing in embryos
A
pronephroi, metanephroi and mesonephroi
9
Q
the pronephroi are
A
the first set and rudimentary
end of 3 weeks - 6.5 weeks (3.5 weeks total)
10
Q
the mesonephroi are
A
the second set and function briefly after the early fetal period
late in 4th week - 8th week (function for 4 weeks)
11
Q
the metanephroi
A
are the 3rd set and form the perma kidneys
begin to develop at 5 weeks and become functional at 9 weeks
12
Q
kidneys develop from 2 sources
A
- ureteric bud = metanephric diverticulum
2. metanephrogenic blastema = metanephric mass of mesenchyme
13
Q
ureteric bud is an outgrowth from
A
the mesonephric duct
outgrowth = diverticulum
14
Q
metanephrogenic blastema is derived from
A
caudal part or nephrogenic cord
15
Q
the blastema is a
A
metanephric mass of mesenchyme
16
Q
mesonephric kidneys consist of
A
glomeruli (10-50 per kidney) and mesonephric tubules
17
Q
mesonephric tubules open into
A
bilateral mesonephric ducts (originally pronephric ducts)
18
Q
mesonephric ducts open into
A
the cloaca
19
Q
mesonephric ducts degenerate towards
A
the end of the 12th week
20
Q
even though mesonephric ducts degenerate, metanephric tubules become
A
the efferent ductules of the testes
mesonephric ducts have several adult derivatives in males
21
Q
stalk of ureteric bud becomes
A
the ureter
22
Q
what part of the ureteric bud undergoes repetitive branching to become collecting tubules
A
the cranial part of the bud
23
Q
first 4 generations of collection tubules do what to form the major calices
A
they enlarge and become confluent
24
Q
what forms the major calices
A
the enlargement and confluence of the first 4 generations of collecting tubules
25
the second 4 generations coalesce to form
the minor calices
26
what forms the minor calices
the coalescence of the second 4 generations of the collecting tubules (aka the major calices)
27
what does the end of each arched collecting tubule do
induces growth of clusters of mesenchyme cells in the metanephrogenic blastema
28
what do clusters of mesenchyme cells in the metanephrogenic blastema form
small metanephric vesicles
29
what do the metanephric vesicles become
metanephric tubules
30
how do the small metanephric vesicles become metanephric tubules
they elongate
31
as branching continues, some metanephric mesenchyme cells condense and form
cap mesenchyme cells
32
what happens to cap mesenchyme cells
they undergo mesenchymal to epithelial transition
33
what do the cap mesenchyme cells become
majority of the nephron's epithelium
34
what invaginates the proximal ends of the tubules
glomeruli
35
tubules differentiate into
proximal and distal convoluted tubules
36
what constitutes a nephron
the nephron loop (loop of henle)
the glomerulus
the glomerular capsule
37
what does a urineferous tubule consist of
1. a nephron = derived from metanephrogenic blastema
| 2. a collecting tubule = derived from ureteric bud
38
number of glomeruli grows gradually during the
10 - 18th weeks
39
number of glomeruli grows rapidly when
from 18 - 36th week (upper limit is reached)
40
nephron formation is completed when
at birth (in non premature births)
41
fetal kidneys are subdivided into
lobes
42
lobulation of fetal kidneys disappears when
usually at end of 1st year of infancy
43
why does lobulation of fetal/ infant children disappear
nephrons increase and grow
44
what causes increase in kidney size after birth
elongation of the proximal convoluted tubules + increase in interstitial tissue
45
when does functional maturation of kidneys + increasing rates of filtration occur
after birth
46
when does glomerular filtration begin
at approx 9th fetal week
47
what is the branching of ureteric bud dependent on
induction by the metanephric mesenchyme
48
what does the metanephric mesenchyme induce
the branching of the ureteric bud
49
differentiation of nephrons depends on
induction by the collecting tubules
50
what do the collecting tubules induce
the differentiation of the nephrons
51
what two structures are involved in reciprocal induction
the ureteric bud and metanephrogenic blastema
52
what process are the metanephrogenic blastema and the ureteric bud involved in
reciprocal induction = interact and induce each other
| to form the perma kidneys
53
nephrogenesis begins
around the beginning of 8th week
54
metanephric tubules connect with the collecting tubules to form
the uriniferous tubules
55
suprrarenal glands are usually (large/small) compared to the kidneys at a fetus
large: they will become smaller during first year of infancy
56
why do kidneys gradually relocate to the abdomen and move farther apart
because the abdomen and pelvis begin to grow so there is space
57
the ascent of the kidneys during development results from
growth of the embryo's body, caudal to the kidneys
58
what initially faces ventrally during the positional changes of the kidneys
the hilum
59
what is the hilum of the kidneys
the entry and exit site for blood vessels, ureter and nerves of the kidneys
60
what happens to the position of the hilum as the kidneys relocate
the hilum rotates medially 90 degrees
61
how does the hilum rotate during kidney relocation
rotates medially 90 degrees
62
when are the hila (plural of hilum) directed anteromedially (final position)
by the 9th week
63
kidneys are (sub/retro/pre/intra) peritoneal structures
retroperitoneal: located outside and behind the peritoneal space
64
shape of left suprrarenal gland
crescent shape
65
shape of right suprrarenal gland
pyramidal
66
renal arteries initially grow from the
common iliac artery
67
as kidneys ascend, the stop receiving blood from common iliac arteries and begin receiving it from
the distal end of the abdominal aorta
68
when kidneys are located at a high level, they receive new arterial branches from the
aorta
69
what happens to caudal branches of the renal vessels after kidney ascension
caudal branches of renal vessels undergo involution (shrinkage) and disappear
70
when do the positions of the kidneys become fixed
once the kidneys meet the suprrarenal glands
71
when do the kidneys meet the suprrarenal glands
in the 9th week
72
the (right/left) renal artery is longer and more superior
right
73
percentage of adult kidneys with 2 - 4 renal arteries
25%
74
from where do accessory renal arteries arise
the aorta (superior or inferior to main renal artery)
75
accessory renal arteries arise (superior/inferior) to the main renal artery
either superior or inferior, can vary
76
accessory renal arteries are also known as
supernumerary renal arteries
77
accessory renal arteries
a) follow the main renal artery through the hilum into the kidneys
or
b) enter the kidneys directly through superior or inferior pole
both A and B are correct
78
supernumerary renal arteries enter the kidney through the (superior/inferior) pole
can enter through either pole
79
hydronephrosis is caused by
an accessory renal artery entering through the inferior pole (polar renal artery) and crossing anterior to the ureter = obstructing ureter
80
in hydronephrosis, the supernumerary renal artery crosses (anterior/posterior) to the ureter
anterior = obstructs the ureter
81
hydronephrosis causes
swelling of the kidney as the urine cannot be drained out
82
swelling of the kidney is caused by
hydronephrosis
83
distension of the renal pelvis and calices by urine is associated with
hydronephrosis (swelling of kidney bc urine cant be drained)
84
accessory renal arteries are
end arteries
85
what happens if an accessory renal artery is damaged/ ligated
part of kidney supplied by it will become ischemic (blood flow AKA oxygen flow is reduced/ restricted)
86
accessory arteries are (more/less) common than accessory veins
more: approx 2 times more common
87
suprrarenal glands can be divided into 2 parts
cortex and medulla
88
origin of cortex of suprrarenal glands
develops from mesenchyme
89
origin of medulla of suprrarenal glands
derived from an adjacent sympathetic ganglion
90
how does the cortex of suprrarenal gland begin developing
begins as an aggregation of mesenchyme cells on each side of embryo (between root of dorsal mesentery and developing gonad)
91
when are the suprrarenal glands simply aggregations of mesenchyme cells
during the 6th week
92
when do the neural crest cells differentiate into secretory cells of the suprrarenal medulla
as they are surrounded by the cortex
93
how is the cortex enclosed
mesenchymal cells arise from mesothelium and enclose it
94
where do neural crest cells form a mass to create the medulla of suprrarenal gland
on the medial side of the embryonic suprrarenal cortex
95
when do the neural crest cells form a mass on the suprrarenal cortex
at 7 weeks
96
what are the 3 layers of the suprrarenal cortex
from most inwards to outwards:
1. zona glomerulosa
2. zona reticularis
3. zona fasciculata
97
what is the zone between the permanent cortex and fetal cortex of suprrarenal glands called
transitional zone
| indentified by immunohistochemical studies
98
from what is the zone/ layer is the zona fasciculata derived
the transitional zone
99
what 2 layers of suprrarenal gland cortex are present at birth
zona glomerulosa and zona reticularis
100
what layer of suprrarenal gland cortex is not present at birth
zona fasciculata
101
when is the zona fasciculata recognizable in the suprrarenal gland cortex
at the end of the 3rd year of infancy
102
relative to body weight, suprrarenal glands are ... times (smaller/larger) than in adult glands
10 - 20 times larger
103
why are the suprrarenal glands so large compared to the kidneys during development
bc of extensive size of fetal suprrarenal cortex = cortex produces steroid precursors
104
what are the steroid precursors secreted by fetal suprrarenal glands used for
used by placenta to synthesize estrogen
105
medulla is relatively (small/large) during development
small: will grow after birth
106
why will the suprrarenal glands rapidly become smaller
bc the fetal cortex will regress during 1st year of infancy
107
when will the fetal suprrarenal cortex regress
during the 1st year of infancy
108
glands lose approx ... of their weight during the 2-3 weeks post birth
1/3 (one third)
109
when do suprrarenal glands lose approx 1/3 of their mass
during the 2-3 weeks post birth
110
when do the suprrarenal glands regain the 1/3 mass lost during 2-3 weeks post birth
end of 2nd year of infancy
111
what happens at the end of the 2nd year of infancy
the suprrarenal glands have regained the mass lost during 2-3 weeks post birth
112
urogenital sinus has 3 parts
vesical part
pelvic part
phallic part
113
what does the vesical part of urogenital sinus do
vesical part: forms urinary bladder and is continuous with the allantois
114
what is continuous with the allantois
the vesical part of the urogenital sinus
115
what does the pelvic part of the urogenital sinus do
pelvic part: becomes urethra in neck of bladder
- in males = prostatic part of urethra
- in females = entire urethra
116
what does the phallic part of the urogenital sinus do
phallic part: grows towards the genital tubercule
| - primordium of the penis OR clitoris
117
from what does the bladder develop
the vesical part of the urogenital sinus
118
entire epithelium of bladder is derived from
endoderm of the vesical part of urogenital sinus
119
endoderm of vesical part of urogenital sinus forms
the epithelium of the bladder
120
endoderm of vesical part also known as
ventral part of cloaca
121
other layers of wall (not epithelium) of bladder develop from
the adjacent splanchnic mesenchyme
122
adjacent splanchnic mesenchyme forms
the other layers (not epithelium) of the bladder wall
123
allantois is
a fetal membrane developed from the hindgut
124
initially bladder is continuous with
allantois
125
allantois will constrict and become a thick fibrous cord called
the urachus
126
the urachus is formed by
the allantois (after it constricts and forms a fibrous cord)
127
the urachus extends from ... to the ...
from the apex of the bladder to the umbilicus
128
in adults, the urachus is represented by
median umbilical ligament
129
what used to be the median umbilical ligament
the urachus
130
why are distal parts of the mesonephric ducts incorporated into dorsal wall of bladder
bc the bladder begins enlarging
131
what happens when the bladder begins growing in size
distal parts of mesonephric ducts begin incorporating into the dorsal wall of bladder
132
connective tissue in the trigone of bladder is formed by
the absorption of the mesonephric ducts which were incorporated into the dorsal wall of the bladder
133
when do the ureters open separately into the bladder
as the mesonephric ducts incorporated into dorsal wall of bladder are absorbed
134
the orifices of the ureters move ... and enter ... through bladder base
move superolaterally and enter obliquely through bladder base
135
why do orifices of ureters move superolaterally and enter obliquely through bladder base
partly bc of traction exerted by kidneys as they ascend
136
in males, what happens to the orifices of the ureter ducts
orifices move closer + enter prostatic part of urethra + caudal ends of ducts develop into ejaculatory ducts
137
in females, what happens to the distal end of the mesonephric ducts
they degenerate
138
where is the bladder in infants and children
in the abdomen (even when empty)
139
when does the bladder begin to enter the greater pelvis
at 6 years old
140
when does the pelvis enter the lesser pelvis (and become a pelvic organ)
after puberty
141
the apex of the bladder in adults is continuous with what structure
the median umbilical ligament
142
the median umbilical ligament is continuous with what structure
in adults
the apex of the bladder
143
where does the median umbilical ligament extend in adults
posteriorly along the posterior surface of the anterior abdominal wall
144
what extends posteriorly along the posterior surface of the anterior abdominal wall in adults
the median umbilical ligament
145
from what is the epithelium of most of the male and the entire female urethra derived
endoderm of the urogenital sinus
146
the endoderm of the urogenital sinus derives what structure
- most of the male urethra
| - the entire female urethra
147
distal part of urethra in glans penis is derived from
a solid cord of ectodermal cells (which grow inwards from the tip and joins rest of spongy urethra)
148
solid cord of ectodermal cells forms what structure
the distal part of the urethra in the glans penis (which grows inwards from tip of glans penis to rest of spongy urethra)
149
how does the solid cord of ectodermal cells that forms distal part of urethra in the glans penis grow
grows inwards from tip of glans penis to rest of spongy urethra
150
what grows inwards from tip of glans penis to rest of spongy urethra
a solid cord of ectodermal cells which forms the distal part of urethra in the glans penis
151
from what is the terminal part of the urethra derived
from surface ectoderm
152
surface ectoderm will form
the epithelium of the terminal part of the urethra
153
connective tissue and smooth muscle of urethra for both sexes is derived from
splanchnic mesenchyme
154
splanchnic mesenchyme will form the
connective tissue and smooth muscle of the urethra for both sexes
