Oviduct - Anatomy & Physiology
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Introduction
The Oviduct is the tube that links the ovary to the uterus and which the ovulated Oocyte travels down to become fertilised by sperm present in the female tract. It is also refered to as the Fallopian tube, Uterine tube or Ovarian tube.
Structure
The oviduct is devided into 3 anatomical regions:
- Infundibulum – The cranial ovarian end of the oviduct. It comprises of numerous fimbrae and the opening into the oviduct tube, the ostium.
- Ampulla – The longest region of the oviduct occupying more than half of its total length and also has the largest diameter. This is the site of fertilisation. It is distinguished by its many mucosal folds. The ampulla is joined to the isthmus via the Ampullary-Isthmus junction. This junction is important in the mare as it acts as a regulatory checkpoint allowing only fertilised ova to pass any further along the oviduct and into the uterus.
- Isthmus – The caudal end of the oviduct joined to the uterus. The Isthmus is thicker walled than the ampulla and smaller in diameter. Its folded mucosa forms a functional reservoire for sperm in the female tract.
Function
- A connecting tube structure between the uterus and ovary where fertilisation occurs.
- To provide regulation check points for unfertilised oocytes.
- The mucosal glands produce oviduct secretions integral for:
- Supporting the unfertilised oocyte
- Supporting spermatozoa in the oviduct
- Increasing the fertilising capabilities of the spermatozoa
- Development of the early embryo
Anatomical Boundaries
- The Oviduct is suspended from the abdominal wall by the mesosalpnix broad ligament.
Histology
Infundibulum
- Fimbriae
- Finger like projections that aid the Infundibulum in gliding over the surface of the ovary. This action enhances the chances of the ovulated Oocyte being captured by the Infundibulum, as ovulation in domestic species does not occur in any one place. The exception to this being the mare, where ovulation always occurs from the ovulation fossa.
Ampulla
- Ciliated Columna Epithelium
- Thin muscularis layer
- Fern like mucosal folds
Isthmus
- Simple columna Epithelium
- Thick muscularis layer divided into inner circular layer and outer longditudinal layer
- few mucosal folds
Innervation
Vasculature
- Tubal branch of the ovarian artery.