Flashcards in Embryology Deck (50)
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1
______ forms in the upper thoracic to upper lumbar region. It develops from superior to inferior, and performs filtration from about ______ weeks gestation (though not all parts at once).
Mesonephros, 4-10
2
____ takes care of filtration for the embryo < 4 weeks
Pronephros
3
Eventually the mesonephros’ filtration function is replaced by the ____ which becomes the
metanephros, adult kidney.
4
Eventually, around week ____ the mesonephros’ filtration function is replaced by the ____ which becomes the
5, metanephros, adult kidney.
5
Primordial germ cells differentiate in _______ and migrate to the ______ at the ___ week
Neck of the yolk sac
Genital ridge
4-5th weeks
6
the "indifferent stage"
- Before 10 weeks
- both male and female genital ducts are present
7
Male duct system develops from the _______
Mesonephric / Wolffian Ducts
8
Female duct system develops from the _____
Paramesonephric / Mullerian Ducts
9
Mesonephric ducts form the _______ in males
epididymis,
ductus deferens,
efferent ducts,
ejaculatory duct
10
Paramesonephric ducts form the _____ in females
fallopian tubes,
uterus,
upper 1/3 to 2/3 of the vagina.
11
Genital duct differentiation begins
during 3rd month of gestation (8-9 weeks)
12
Genital duct differentiation begins
during 3rd month of gestation (8-9 weeks)
13
______ causes Wolffian (mesonephric) ducts to differentiate into male genital structures, the gonads to become testes
TDF (Testes determining factor)
14
The testes make _______ to cause the mullerian/paramesonephric ducts to regress
Mullerian Inhibiting Substance
15
Primary sex cords of testes containing the primordial germ cells, and are located __
Testes cords (spermatic cords), medulla of testes
**spermatic cords are solid until puberty, when then canalize and become Seminiferous Tubules**
16
Spermatic cords contain what two types of cells
(epithelial cells >>) Sertoli cells ("nurse" cells for sperm)
(primordial germ cells >>) Spermatoblasts
17
With puberty, spermatic cords become the
Seminiferous Tubules
18
Cells within the seminiferous tubules which make testosterone
Cells of Leydig
19
What if testes fail to ever develop in the fetus, or are removed from the fetus very early on?
Paramesonephric ducts will be uninhibited (by MIS) and will become female genetalia
20
What if ovaries fail to develop or are removed in the female fetus?
Has no effect on fetal sexual development– still female genitalia
21
What if ovaries fail to develop or are removed in the female fetus?
Has no effect on fetal sexual development– still female genitalia
22
a common opening shared by the digestive, reproductive, and the urinary tracts.
Cloaca
23
A ______ develops at the anterior end of the cloacal membrane/ Elongates to form the Phallus
genital tubercle
24
Fusion of the ______ makes the scrotum.
Fusion of the ______creates the penis and the elongated urethra.
Labioscrotal folds
Urogenital folds
25
Incomplete fusion of the ureteral folds.
Typically more distal, though proximal variations can occur.
Hypospadia
26
The testicles descend to the level of internal inguinal ring at about which time point during gestation?
7th month
27
The testicles descend to the level of internal inguinal ring at about which time point during gestation?
7th month
28
Ovary cannot be defined histologically until
10th week
29
The sex cords which become seminiferous tubules in males become what in females
Primordial follicles
30
Each primordial follicle consists of
Oogonium (from primordial germ cells)
Follicular cells (from surface epithelium, surround oogonium)
31
About how many oogonium remain to become primary oocytes at birth
2 million
32
by puberty about how many oocytes remain
500,000
33
by puberty about how many oocytes remain
500,000
34
Mesonephric ducts will form the _____ which will deliver sperm to the region of the prostate
Ductus Deferens
35
The paramesonephric ducts fuse to form_________ in the midline and will become the ______
a Y-shaped uterovaginal primordium
Uterus and superior portion of vagina
36
The uterine (fallopian) tubes develop from ____
the unfused, cranial part of the paramesonephric ducts.
37
When the paramesonephric ducts fuse, the process also brings together two sides of a peritoneal fold that, when folded together, form the
broad ligament
38
An enlargement at the end of the____ induces the formation of paired endodermal outgrowths called ____
urogenital sinus
sinovaginal bulbs.
39
The sinovaginal bulbs fuse to form a
vaginal plate.
40
The two sets of tissue which fuse and canalize to form the vagina
urigenital sinus
sinovaginal bulbs
41
The precursor for all steroid hormones is ___
cholesterol
42
Progesterone is both
an active steroid hormone and an important intermediary.
43
What would happen if 21α-hydroxylase was missing
Progesterone wouldnt be able to convert into Aldosterone and Cortisol
The extra progesterone instead would be converted to testosterone (/estrogens)
44
What would happen if 11 β-hydroxylase was missing
Same as 21α - Abundance of testosterone, shortage of Cortisol and Aldosterone
45
Congenital adrenal hyperplasia is usually due to deficiency in which enzyme
21α-hydroxylase
Deficiency of Cortisol (and sometimes Aldosterone) occurs, which causes fetal pituitary to make more ACTH.
With enough ACTH, finally cortisol is made… but MUCH MORE androgen is made as well.
The adrenals enlarge because of all the cortisol precursor they make
46
Urine test for CAH
Serum 17-OHP, will be elevated
47
A less-active form of estrogen, created in low levels in fat cells when steroids are stored there
Estrone
48
The major form of estrogen made by the ovaries
The most hormonally-active form of estrogen
Estradiol
49
Much less active form
Created in small amounts in the liver
Created in higher amounts in the placenta
Can be used as a marker for NTD’s
Estriol
50
