Microscopical characteristics of uterine wall arteries in barren aged mares.

This research article examines the morphology of arteries in the uterine wall of aged and infertile horses, revealing common features of deterioration known as ‘elastosis’ and potentially pointing to a primary cause of pregnancy failure in these animals.

Study Subjects and Purpose

• The study was performed on three multiparous mares – mature female horses that have given birth more than once. These horses had all experienced repeated pregnancy failure in later life.
• The reason for studying these particular mares was to determine any abnormalities in the uterine walls that could be linked to their infertility.

Investigation of Uterine Wall Arteries

• The researchers focused on the morphology, or shape and structure, of the arteries within the uterine wall of these mares.
• They found that these arteries exhibited elastosis – a condition where there is abnormal accumulation of elastic tissue fibres – either in the intima (inner layer) or adventitia (outer layer) of the arterial walls, or both.
• This physical state resembled a health condition known as ‘physiological pregnancy sclerosis’, essentially a hardening of tissue due to excessive growth that can occur during pregnancy.

Elastosis and its Effects

• In the areas of the uterine wall arteries affected by elastosis, the researchers frequently noticed degeneration of pre-existing elastic fibres and an increase in a type of complex carbohydrates called glycosaminoglycans.
• No evidence of newly formed elastic fibres was found, which would suggest a healthy turnover of these tissue components.
• The researchers theorised that this situation – an increase in old, degenerated elastic fibres without the emergence of new ones – might be due to delayed resorption, which is a process where old tissue components are taken back into the body for recycling or elimination.
• If the metabolic turnover, or the breakdown and renewal of tissue, is disordered, it might lead to the accumulation of elastic fibres, resulting in elastosis.
• This elastosis of the uterine wall arteries could be a significant factor contributing to the repeated pregnancy failures experienced by the mares in this study.

In conclusion, this study offers important insights into the physical changes in the uterine walls in barren aged mares and potentially sheds light on causes of infertility in these animals. Further research may desire to validate these findings and explore methods to diagnose or treat this condition in veterinary medicine.