4,503
edits
Changes
Follicles - Anatomy & Physiology (view source)
Revision as of 12:42, 9 September 2008
, 12:42, 9 September 2008→Follicular Development
==Follicular Development==
==Follicular Development==
'''Primordial Follicle'''
=== '''Primordial Follicle''' ===
[[Image:Primordial Follicle.jpg|thumb|right|150px|Histological Section of the Ovary showing Characteristics of the Primordial Follicle- Courtesy of J.Bredl, Copyright RVC 2008]]
[[Image:Primordial Follicle.jpg|thumb|right|150px|Histological Section of the Ovary showing Characteristics of the Primordial Follicle- Courtesy of J.Bredl, Copyright RVC 2008]]
*Smallest and most immature follicle
*Smallest and most immature follicle
*Oocyte surrounded by a Single layer of squamous cells
*Oocyte surrounded by a Single layer of squamous cells
'''Primary Follicle'''
=== '''Primary Follicle''' ===
*Oocyte surrounded by a single layer of follicular cuboidal cells.
*Oocyte surrounded by a single layer of follicular cuboidal cells.
'''Secondary Follicles'''
=== '''Secondary Follicles''' ===
*The oocyte had developed a thick translucent glycoprotein layer called the Zona Pellucida.
*The oocyte had developed a thick translucent glycoprotein layer called the Zona Pellucida.
*Oocyte surrounded by two or more layers of follicular cuboidal cells. These cells differenciate into the inner Granulosa cells and outer Theca cells.
*Oocyte surrounded by two or more layers of follicular cuboidal cells. These cells differenciate into the inner Granulosa cells and outer Theca cells.
'''Tertiary/Antral Follicles'''
=== '''Tertiary/Antral Follicles''' ===
*The innermost cells of the Granulosa layer become firmly attached to the Zona Pellucida and are known as the Corona Radiata. The outermost Granulosa cells become attached to the basement membrane surrounding them and become known as the Theca Folliculi.
*The innermost cells of the Granulosa layer become firmly attached to the Zona Pellucida and are known as the Corona Radiata. The outermost Granulosa cells become attached to the basement membrane surrounding them and become known as the Theca Folliculi.
*Granulosa cells secrete fluid which accumulates within the follicle forming an Antrum.
*Granulosa cells secrete fluid which accumulates within the follicle forming an Antrum.
*Theca Cell layer becomes vascularised.
*Theca Cell layer becomes vascularised.
*Granulosa cells become responsive to Follicle Stimulating Hormone (FSH) and start producing [[Endocrine_System_-_Ovaries_-_Anatomy_%26_Physiology|17β-Oestrodiol]] and small amounts of Inhibin and Progesterone.
*Granulosa cells become responsive to Follicle Stimulating Hormone (FSH) and start producing [[Endocrine_System_-_Ovaries_-_Anatomy_%26_Physiology|17β-Oestrodiol]] and small amounts of Inhibin and Progesterone.
'''Dominant Follicle'''
=== '''Dominant Follicle''' ===
*Only a single Dominant follicle forms with each wave of folliculogenesis.
*Only a single Dominant follicle forms with each wave of folliculogenesis.
*The follicles Antrum enlarges due to the Granulosa cells becoming receptive to LH.
*The follicles Antrum enlarges due to the Granulosa cells becoming receptive to LH.