ANHB2216 Lecture Notes - Lecture 5: Female Reproductive System, Sertoli Cell, Rete Testis

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Lecture'5:'Life'Cycle'1:'Sexual'Differentiation:'
'
Sex'and'Gender:'
!
Biological!Sex:!
-!Chromosomal!sex!
-!Genetic!sex!
-!Gonadal!sex!
-!Phenotypic!sex!
!
Gender:!
-!Gender!roles!
-!Gender!identity!
-!Gender!presentation!
!
-!Legal!recognition!of!sex!and!gender!in!documents!and!government!records!tended!to!be!
determined!by!phenotypic!sex!
-!Now!people!can!now!note!which!gender!they!identify!as!
!
Sex'Determination:'
'
-!Experiments!of!Alfred!Jost!~!1940s!
o!Female!is!the!default!type!
!
Chromosomal!Sex:!Karyotypes:!
-!Some!individuals!can!have!varying!
karyotypes:!
!
Karyotype'
Phenotype'
46!XX!
Normal!Female!
46!XY!!
Normal!Male!
45!XO!
Turners!Syndrome!(F)!
47!XXX!
Triple!X!(F)!
47!XYY!
Double!Y!(M)!
47!XXY!
Klinefelter’s!Syndrome!(M)!
!
-!Femaleness!the!‘default’!mode!
-!Gene(s)!on!the!Y!chromosome!!!make!a!testis!
!
Genetic'Sex:'
!
-!XY!female!–!deletion!or!mutation!
in!a!short!piece!of!DNA!on!Y!
chromosome!
-!XX!male!–!presence!of!a!small!bit!
of!‘Y!chromosome’!DNA!on!X!
chromosome!
!
-!Error!during!crossing!over!in!
meiosis!(spermatogenesis)!
o!Prophase!1!
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Presence!of!SRY!gene!on!Y!chromosome:!
-!SRY!protein:!‘Testis!Determining!Factor’!(TDF)!
o!Sets!off!a!cascade!of!other!actions!!!development!of!testis!!!hormones!produced!by!
testis!!!male!characteristics!
o!Organises!testis;!Sertoli!cells,!Leydig!cells,!spermatogonia!
-!Absence!of!SRY!gene!(WNT4!–!chromosome!1!and!FOXL2!–!chromosome!3)!!!SRY!gene!
overrides!these!genes!in!male!!
o!Ovary:!Granulosa!cells,!Theca!cells,!oogonia!
!
Gonad'Formation:'
!
Gonad!comprised!of!two!tissue!types:!
-!Mesenchyme!!!matrix!of!gonad!
-!Primordial!germ!cells!!!gametes!
!
3-5!weeks:!Primordial!germ!cells!(PGC)!migrate!from!yolk!sac!!!genital!
ridge!
!
6!weeks:!epithelium!of!genital!ridge!!!somatic!support!cells!which!later!
!!granulosa!OR!sertoli!cells!
o!Gonad!is!indifferent!
!
7!weeks:!WITH!SRY!GENE!(MALE):!
!
-!SRY!gene!expressed!in!somatic!support!cells!!!Sertoli'cells!
!
-!Sertoli!cells!form!the!testis'cords!enclosing!PGC!
!
-!Testis!cords!elongate!!!seminiferous'tubules!(at!puberty!
become!hollow!and!form!tube)!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!rete'testis'!
!
-!Leydig'cells!differentiate!from!mesenchyme!cells!about!week!9-10!
!
-!Sertoli!cells!produce!AMH!(Antimullerian!hormone)!
!
-!Leydig!cells!secrete!Testosterone!
!
o!!!influence!developing!duct!systems!
!
7!weeks:!WITHOUT!SRY!GENE!(FEMALE):!
!
-!PGC!differentiate!into!oogonia!and!are!surrounded!by!somatic!
support!cells!
!
-!Oogonia!!!Primary'oocyte!and!enter!Meiosis!I!
!
-!Somatic!support!cells!!!follicle'(granulosa)'cells!!
!
-!Follicle!cells!surround!oocyte!to!form!primordial'follicle!
!
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Development'of'Internal'and'External'Genitalia:'
'
Male:!
-!Development!of!male!internal!and!external!genitalia!
is!dependent!on!hormone!activity!of!the!fetal!testis!
o!Antimullerian!hormone!(AMH)!
o!Testosterone!
!
-!Formation!of!female!genitalia!occurs!in!the!absence!
of!Testosterone!and!AMH!
!
Internal!Genitalia:!
!
7!weeks:!two!duct!systems!are!present!!
-!Mesonephric!=!male!
-!Paramesonephric!=!female!
!
12!weeks:!differentiation!
-!-!T!&!AMH:!1/3!vagina,!uterus,!uterine!tube!
-!+!T!&!AMH:!Epididymis,!Vas!deferens,!seminal!vesicles!
!
!
!
!
!
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