Serum hormonal and stereologic evaluation of term chorioallantoic membrane in mares: influence on the development and in clinical and metabolic parameters of the foal.

Author(s)

Marcela Gonçalves Meirelles

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2014-07-03

Examining board members

Claudia Barbosa Fernandes; Estela Maris Andrade Forell Bevilacqua; Cassia Maria Barroso Orlandi

• Advisor: Claudia Barbosa Fernandes

Abstract

Many factors may influence placental and fetal development in the mare, like age, parity and maternal size. The production of steroid hormones by fetal-placental unit can also be influenced by parity and breed, but there are no previous reports relating the effects of the mares age on the production of these hormones during pregnancy. This paper has three main objectives: the first investigated the influence of maternal age and parity on placental efficiency and size of the foal at birth, using stereological analysis of the term placenta. The second determined the influence of parental size on macro and microscopy of the placenta and consequences for fetal development and growth, behavior and postnatal physiological functions. Finally, the influence of maternal age and parity was evaluated, and the breed´s foal in the production of plasmatic oestrogens, progesterone and cortisol in pregnant mares. Forty pregnant females were categorized according to age (Id1: 4-8 years; Id2: 8-12 years; Id3: ≥ 13 years), parity (Par1: nulliparous, Par2: 1 to 3 births; Par3: ≥ 4 births) and foal´s breed (MP: Mangalarga Paulista; BH: Brazilian Sporthorse). Plasma samples were collected weekly from the fifth month of pregnancy to term, and quantification of hormones was performed by Mass Spectrometry. Deliveries were accompanied and Apgar score, behavior and blood samples for biochemical analysis of the foals were collected within the first twelve hours of life. The chorioallantoic membranes were collected after delivery, weighed and photographed to scale. Tissue sections were collected from regions: uterine body, pregnant uterine horn and contralateral uterine horn to be analyzed stereologically. Neonate´s growth parameters were compared from birth up to two years old, as well as data on maternal and paternal height, weight, and thoracic perimeter were collected. No significant differences were observed in the quantification of steroids when considering maternal parity and foal´s breed for the mares groups. The concentrations of oestrogens were significantly higher in Id2 group when compared with Id3, in some months of the gestational period evaluated. It was observed that maternal age and parity influence the development of the microcotyledons and total villi surface density, as well as the vascularization and tissue composition of different regions of the placenta, contributing in fact to a larger area of fetomaternal contact and transfer of gases and nutrients between mother and fetus, culminating with foals that were taller, heavier and with larger thoracic circumference at birth. The paternal, and mainly maternal size, influenced the development of fetal villi and the area of fetomaternal contact surface with a positive effect on the development and fetal growth, resulting in the birth of foals with better metabolic and adaptive responses. It also highlights that the period of intrauterine life was decisive for the postnatal growth rate up to 24 months of life. (AU)

• FAPESP's process: 11/16387-6 - Serum hormone, stereology and immunohistochemistry evaluation of the term chorioallontoic membrane of mares: influence on the development and clinical and metabolic parameters in the foal.
• Grantee: Marcela Gonçalves Meirelles
• Support Opportunities: Scholarships in Brazil - Master