Fetal external features and morphology of the umbilical cord of wild boars

Abstract

This study aimed to describe the gestational and morphological aspects of the fetuses and their respective umbilical cords from two pregnant wild boars (Sus scrofa). Morphological descriptions were provided for 23 fetuses and the gestational ages were estimated through fetal characteristics and formula application. The specimens were fixed in 10% formalin for subsequent macroscopic and microscopic examination. Histological characterization was performed using haematoxylin–eosin (H&E), Masson's trichrome (MT) and Verhöeff's staining techniques. The wild boar fetuses exhibited an estimated gestational age of 55 days (in the larger uterus) and 45 days (in the smaller uterus). They displayed well-developed features consistent with domestic pig fetuses, except for the presence of five pairs of mammae. Additionally, the umbilical cord consisted of two arteries, one vein, an allantoic duct, and a vitelline duct (the latter two identified only microscopically), located in the juxtafetal, intermediate and juxtaplacental portions. The arteries and veins were comprised of endothelium, smooth muscle and collagen fibres, with no elastic fibres observed in the vessel walls. The allantoic duct was lined with simple cuboidal epithelium, while the vitelline duct featured a simple squamous epithelium. In conclusion, the morphological characteristics observed in the examined structures align with the expected patterns for species of the Suidae family. Furthermore, these findings contribute substantially to the morphological characterization of the wild boar, yielding valuable insights into the fetal morphology and the structure of the umbilical cord.