Scanning electron microscopy of the microcotyledonary placenta of the horse (Equus caballus) in the latter half of gestation.

This research examined the detailed structure of the pony placenta during the second half of pregnancy using scanning electron microscopy, revealing the different developmental changes that occur throughout this period.

Methodology

• The researchers used Scanning Electron Microscopy to investigate the microstructure of the maternal and fetal placenta in 25 pregnant ponies. They analyzed samples from different stages of the second half of gestation.
• The placental samples were collected from specific areas and at different points in time including 105 days, 165-219 days, 260 days, 270-277 days, and 313-337 days, as well as immediately after birth. The size of the sampled area ranged between 2-6 cm2.

Findings

• The researchers observed that the maternal microcaruncle, a part of the horse placenta, appears to be constructed from a cluster of about 16 uterine crypts, which are small hollows or cavities. This cluster is covered in a sheath of connective tissue.
• Throughout the second half of pregnancy, there’s an increase in the depth of the maternal microcaruncle. This suggests that this part of the placenta undergoes significant developmental changes during this period.
• The fetal microcotyledon, another part of the placenta, seems to be formed by a clustering of individual fetal villi, which are small, fleshy projections from the placenta.
• There was significant growth in the length and branching of the villi during the final 2-3 months of gestation. They found that tufts emerged from the base of the main plant, with a stem bearing 3-6 branches.
• Branching did not only occur at the base of the primary stem, but also along the secondary and tertiary branches. This suggests a complex and robust development pattern within the placental structure.
• Close to birth, there was evidence of additional branching at the tips of the villi. This indicates that there are still active developmental changes in the placental structure even in the last days before delivery.

Conclusion

• The study provides detailed insights into the microstructure and developmental changes of the horse’s placenta during the latter part of gestation, which can help in understanding the physiological mechanisms supporting fetal growth and development.
• This research could be used as a foundation for further studies into equine reproduction and may also provide comparative data for studying placental structure in other mammalian species.