Ultrastructural studies of the equine uterus and placenta following parturition.

This study examines the changes in the structure of the horse’s uterus and placenta after giving birth, in both normal and abnormal births. The research found minimal damage to the mother or baby after a normal birth and by the third and fourth day after giving birth, the uterus was largely reverted back to its normal state. However, in abnormal births, damage was observed in both the mother and baby.

Objectives & Methodology

• The study aimed to investigate changes in the mare’s uterus and placenta following both normal and abnormal foalings or births.
• It used ultrastructural studies, which involve interrogating the detailed structure of biological materials using high-resolution microscopy.
• Post-partum placentae and uterine biopsy samples were collected and analyzed to identify the structural changes.

Findings

• In normal deliveries, there was minimal damage to fetal or maternal tissues.
• The study found that the placenta, which specifically is of the type known as villous epitheliochorial placenta, separates cleanly from the maternal-fetal interface. This means that the afterbirth consists almost entirely of fetal tissue.
• Uterine involution or the process of the uterus returning to its normal size is well advanced by the 3rd and 4th days post partum. This process is typically completed by the oestrus 7–10 days after parturition.

Abnormal Foalings

• The process of placental separation and uterine involution was found to be normal in malpresented foals and in otherwise viable foals with musculoskeletal defects.
• In contrast, in cases of aborted, stillborn, or dysmature foals, there were clear signs of damage to both fetal and maternal tissues.

Implications

• The findings underscore the accepted belief that the growth and development of the fetus relies on a placenta with sufficient functional capabilities.
• The research also suggested that the placenta’s health is similarly dependent on its association with a normal, healthy fetus. In essence, a viable and healthy pregnancy is a two-way street with both mother and baby playing a key role.