Block 4 Embryology Md 1 Genital Part A

Front 1

Starts at slide 149

Back 1

.

Front 2

Genetic sex is established at =,

Back 2

fertilization

Early genital development is referred to as the =

Hint 2

indifferent stage of sexual development

Front 3

the gonads do not begin to attain sexual characteristics until week

Back 3

7

Front 4

the external genitalia do not acquire distinct masculine or feminine characteristics until week =.

Back 4

12

Front 5

*** The gonads (testes and ovaries) are derived from three sources:

Back 5

mesothelium
mesenchyme
primordial germ cells.

Front 6

***The mesothelium (mesodermal epithelium) lining the

Back 6

posterior abdominal wall

Front 7

*** The underlying mesenchyme (embryonic

Back 7

connective tissue

Front 8

Recall: Primordium : the beginning of an

Back 8

organ or structure

The primordium of upper limb appears as a =

Hint 8

a bud (Limb bud).

Front 9

Indifferent Gonads
During the ______ week a thickened area of ________ $
develops on the medial side of the mesonephros.

Back 9

5th

mesothelium

Front 10

Proliferation of this epithelium and the underlying mesenchyme produces a bulge on the medial side of the mesonephros - the =

Back 10

gonadal ridge/cord.

Front 11

gonadal ridge/cord. comes from = $

Back 11

mesothelium
mesenchyme

Front 12

Thickened area of ____________ develops on the medial side of the mesonephros.

Back 12

mesothelium


Proliferation of this epithelium produces a bulge on the medial side of the =

Hint 12

mesonephros - the gonadal ridge/cord.

Front 13

Fingerlike
gonadal cords –
soon grow into the
underlying

Back 13

Mesenchyme

The indifferent
gonad now consists
of an =

Hint 13

external
cortex and an
internal medulla

Front 14

In embryos with an XX sex chromosome complex, the cortex of the indifferent gonad differentiates--- into

Back 14

an ovary and =

Hint 14

the medulla--- regresses.

Front 15

In embryos with an XY sex chromosome complex, the medulla--- differentiates into a =

Back 15

testis and the cortex--- regresses, except for =

Hint 15

vestigial remnants.

Front 16

Transverse section through the GC in the __week =

Back 16

8th

pic

Hint 16

Front 17

Transverse section of the GC at the __ week

Back 17

7th

pic

Hint 17

Front 18

Recall:The gonads (testes and ovaries) are derived from three sources: =

Back 18

The mesothelium,

The underlying mesenchyme,

The primordial germ cells)

Front 19

The primordial germ cells form in the wall of the yolk sac (endodermal origin) during week =

They later migrate into the developing gonads at week

Back 19

4

6

and differentiate into the definitive germ cells--

Hint 19

oogonia/spermatogonia

Front 20

primordial germ cells form in the wall of the

Back 20

yolk sac during week 4.

They later migrate into the developing gonads and differentiate into the =

Hint 20

definitive germ cells.

Front 21

Before the ___ week, the gonads of the two sexes are identical in appearance and are called =

Back 21

7th

indifferent gonads

Front 22

Development of the male phenotype requires a =

Back 22

Y chromosome

Front 23

The SRY gene for a testis-determining factor (TDF) has been localized in the sex-determining region of the =

Back 23

Y chromosome on the short arm.

Front 24

The ___ gene for a testis-determining factor (TDF) has been localized in the____________________ chromosome on the short arm.

Back 24

SRY

sex-determining region of the Y

Front 25

Under the influence of TDF, the gonadal cords differentiate into =

Back 25

seminiferous cords
(primordia of seminiferous tubules)

Front 26

absence of a Y chromosome
results in the formation of an

Back 26

(i.e., an XX sex chromosome complement)

Testosterone, produced by the fetal testes, determines maleness.

Front 27

The first step in the development of the testes is the formation of the =

Back 27

tunica albuginea

a layer of fibrous connective tissue which separates the =

Hint 27

sex cords/Gonadal cord
(now known as seminiferous cords)
from the surface epithelium.

Front 28

Within the tunica albuginea, the seminiferous cords are separated from one another by mesenchyme. This mesenchyme will go on to produce the =

Back 28

Leydig cells.

Hint 28

Front 29

_____ _____ are important as they produce
testosterone which travels to receptors in the
mesonephric duct.

Back 29

Leydig cells

This maintains the
presence of these mesonephric ducts (as
opposed to the female embryo where the duct
degenerates).

Front 30

The seminiferous cords also have an important role in male differentiation. The cords are solid (i.e. no lumen) =

Back 30

until puberty

are made up of a large number of Sertoli cells, a highly proliferative cell which secretes =

Hint 30

antimullerian hormone.

Front 31

Antimullerian hormone inhibits the ______________ ducts which then degenerate around the __week of development.

Back 31

paramesonephric

9th

Front 32

The seminiferous cords remain solid until puberty at which time a lumen develops and they become the =

Back 32

seminiferous tubules.

Hint 32

Front 33

■Gonadal cord
(mesothelium ,mesenchyme, primordial GC)

Back 33

■Gonadal cord
seminiferous cords develop
tubuli recti,
rete testis

Front 34

The rete testis becomes continuous with 15 to 20 mesonephric tubules that become =

Back 34

efferent ductules (ductuli efferentes)

Front 35

►These ductules are connected with the mesonephric duct, which becomes the =

Back 35

duct of the epididymis.