Physiology of the Reproductive Tract

Chapter 3 Physiology of the Reproductive Tract



Ovulation 46
Female Reproductive Physiology 46

Hypothalamus 49

GnRH 50

FSH 50

LH 50

Ovulation 50

Cyclical Ovarian Hormonal Changes 51
Oestrogens 51

Progesterone 51

Endometrial Cycle 51

Action of Ovarian Hormones 52
Oestrogen 52

Progesterone 52

Target Tissues 52

Effects of Ovarian Hormones 53
Genital Tract 53

Breast 53

Hypothalamus 53

Cardiovascular System 53

Skeleton 53

Psychological Characteristics 53

Puberty 54

The Menopause 55


Ovulation



Female reproductive physiology


During reproductive life, the cyclical development of ovarian follicles is the dominant process. The associated hormonal production has significant effects on the female genital tract, hypothalamus and pituitary.


In men, gamete production continues throughout life, whereas women develop their life supply of gametes during intrauterine life. See Chapter 1. The numbers decline even before birth, and there will be around 300,000 remaining at puberty.


The surface of the ovary is covered by a cuboidal ‘germinal’ epithelium. This layer is contiguous with the peritoneum. Underneath the epithelial layer is a thin layer of fibrous tissue, beneath which is the true cortex.



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The cortex consists of a specialised stroma or parenchyma; the primordial follicles are embedded in this layer.



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The primordial follicle consists of a primary oocyte surrounded by a single layer of flattened cells, the pre-granulosa, said to be derived from the cells of the sex cords.


The pre-granulosa cells become cuboidal and proliferate to form a shell several layers thick. At this stage, a hyaline membrane is formed immediately around the ovum – the zona pellucida.


The granulosa cells continue to proliferate until the follicle is approximately 200 μm in diameter. Fluid spaces now appear between the granulosa cells. They coalesce to form a cavity, the antrum, pushing the ovum to one side. The granulosa cells immediately surrounding the ovum are now known as the corona radiata, and the whole mass of cells in this situation is termed the cumulus oophorus.



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At the same time, the surrounding parenchymal cells arrange themselves concentrically around the follicle. The cells opposite the ovum become smaller and more epithelial in appearance. As the follicle increases in size, this epithelial change spreads to the parenchymal cells around the circumference of the follicle. This band of cells constitutes the theca interna. The cells are surrounded by sinusoidal capillaries, thus forming an endocrine gland-like structure. External to this band, the parenchymal cells are also arranged concentrically but retain their fusiform shape.



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Related posts:

  1. Diseases of the Vagina
  2. Gynaecological Infections
  3. Diseases of the Cervix
  4. Abnormalities of Menstruation

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Jun 4, 2016 | Posted by in GYNECOLOGY | Comments Off on Physiology of the Reproductive Tract

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