Oocyte Development: Difference between revisions

Revision as of 10:32, 13 May 2010

Introduction

--Mark Hill 10:32, 13 May 2010 (EST) Page template only. Content being prepared.

Female Gametogenesis

In females, the total number of eggs ever to be produced are present in the newborn female.

All eggs are arrested at an early stage of the first meiotic division as a primary oocyte (primordial follicle). Following purberty, during each menstrual cycle, pituitary gonadotrophin stimulates completion of meiosis 1 the day before ovulation.
In meiosis 1, a diploid cell becomes 2 haploid (23 chromosomes) daughter cells, each chromosome has two chromatids. One cell becomes the secondary oocyte the other cell forms the first polar body.
The secondary oocyte then commences meiosis 2 which arrests at metaphase and will not continue without fertilization.
At fertilization meiosis 2 completes, forming a second polar body. Note that the first polar body may also undergo this process forming a third polar body.

Female Abnormalities

Trisomy 21 female karyotype

Meiotic non-disjunction resulting in aneuploidy, most are embryonic lethal and not seen. The potential for genetic abnormalities increase with maternal age.

Autosomal chromosome aneuploidy
- trisomy 21 - Down syndrome
- trisomy 18 - Edwards syndrome
- trisomy 13 - Patau syndrome

Sex chromosome aneuploidy
- monosomy X - Turner's Syndrome
- trisomy X - Triple-X syndrome
- 47 XXY - Klinefelter's Syndrome

References

Search

NCBI Bookshelf oocyte | oogenesis | oocyte development

Pubmed oocyte | oogenesis | oocyte development

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2024, April 16) Embryology Oocyte Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Oocyte_Development

What Links Here?

@@ Line 1: / Line 1: @@
 ==Introduction==
+--[[User:S8600021|Mark Hill]] 10:32, 13 May 2010 (EST) Page template only. Content being prepared.
 [[File:Human-oocyte.jpg]] [[File:Human_oocyte-metaphase_I.jpg]] [[File:Human_oocyte-metaphase_II.jpg]]
@@ Line 8: / Line 10: @@
 '''Links:'''  [[2009_Lecture_2|2009 Lecture - Fertilization]] | [[2009_Lecture_3|2009 Lecture - Week 1 and 2]] | [[2009 Lecture 16|2009 Lecture - Genital Development]] | [[Zona pellucida]] | [[Spermatozoa]] | [http://embryology.med.unsw.edu.au/Notes/genital.htm original Genital Notes] | [http://embryology.med.unsw.edu.au/Notes/urogen.htm original Urogenital Notes]
+== Female Gametogenesis ==
+In females, the total number of eggs ever to be produced are present in the newborn female.
+# All eggs are arrested at an early stage of the first meiotic division as a primary oocyte (primordial follicle). Following purberty, during each menstrual cycle, pituitary gonadotrophin stimulates completion of '''meiosis 1''' the day before ovulation.
+# In '''meiosis 1''', a diploid cell becomes 2 haploid (23 chromosomes) daughter cells, each chromosome has two chromatids. One cell becomes the secondary oocyte the other cell forms the first polar body.
+# The secondary oocyte then commences '''meiosis 2''' which arrests at metaphase and will not continue without fertilization.
+# At fertilization '''meiosis 2''' completes, forming a second polar body. Note that the first polar body may also undergo this process forming a third polar body.
+[[File:Female_gametogenesis.jpg|600px|Female gametogenesis]]
+===Female Abnormalities===
+[[File:Trisomy21female.jpg|thumb|Trisomy 21 female karyotype]]
+Meiotic non-disjunction resulting in aneuploidy, most are embryonic lethal and not seen. The potential for genetic abnormalities increase with maternal age.
+* Autosomal chromosome aneuploidy
+** trisomy 21 - [[trisomy 21|Down syndrome]]
+** trisomy 18 - Edwards syndrome
+** trisomy 13 - Patau syndrome
+* Sex chromosome aneuploidy
+** monosomy X - Turner's Syndrome
+** trisomy X - Triple-X syndrome
+** 47 XXY - Klinefelter's Syndrome
 ==References==