Evolução morfométrica dos anexos embrionários e fetais bovinos obtidos por monta natural, com 10 a 70 dias da gestação

Abstract

O período inicial da gestação de bovinos é caracterizado por grandes perdas embrionárias. Considerando a importância deste fator no âmbito da reprodução animal foram estudados os anexos embrionários e fetais bovinos fecundados por monta natural de 15-70 dias de gestação, com o objetivo de estabelecer parâmetros morfométricos da placenta na fase inicial da gestação. Com uso de um paquímetro foram realizadas mensurações do comprimento (crânio caudal), largura (latero lateral) e altura (dorso ventral) das membranas corioalantóide e amniótica. O início da formação dos cotilédones foi observado e quantificado, assim como, o peso placentário. O peso médio do saco gestacional aumentou com o evoluir da idade gestacional, entretanto, o crescimento foi acelerado a partir de 20-30 dias de gestação. O comprimento crânio caudal e dorso ventral da membrana corioalantóide e do âmnio apresentaram crescimento lento e gradual com o evoluir dos períodos gestacionais analisados. Com 30-40 dias de gestação, os primeiro cotilédones já eram visualizados e contatos com facilidade na superfície coriônica. Os períodos de crescimento coincidiram com os maiores índices de perdas gestacionais em bovinos. Os parâmetros aqui analisados poderão servir para futuras investigações dos anexos embrionários de organismos manipulados em laboratório.

A morphological analysis of the transition between the embryonic primitive intestine and yolk sac in bovine embryos and fetuses

“…However, vestiges of the central part of this sac can be observed during this time. Assis Neto et al (, 2011) have described other features of membrane development in bovines.…”

Gestational losses after innovating with two embryos in a fixed-time embryo transfer program

“…It is known that modifications in the chorion (Costa et al, 2020), in the allantois (Thompson et al, 2000) and in the yolk sac (De Sousa et al, 2001) resulted in pregnancy losses. Also, despite not having been the focus of this experiment, it is possible to consider that the losses may have been caused by situations related to the development of cotyledons (Assis Neto et al, 2009), or by changes at the cellular and/or matrix level extracellular, mainly of structures called glycosaminoglycans and proteoglycans, which are responsible for ensuring hydration, tissue elasticity and have a fundamental role in vascular growth that accompanies the development of the placenta (Reynolds et al, 2001).…”

Morphological and Molecular Analysis of In Vitro Tubular Structures from Bovine Yolk Sac-Derived MSCs

“…The protocols used for this research were approved by the research ethics committee (1.656743/2011) of the Faculty of Animal Science and Food Engineering, University of São Paulo, Brazil. The uterus was collected in the slaughterhouse via incision; the embryos were analysed by measuring the crown–rump (CR) length, following previously described methodology [ 3 , 8 ]. As the yolk sac reduced in size during gestation, collected embryos were characterized into groups ( n = 3) according to the CR measurement - 25 to 34 days (crown–rump 0.3 to 1.4 cm) and separated into group I (25-29 days) and group II (30-34 days).…”

“…The yolk sac (YS) is a very important embryonic attachment in the study of embryonic development for cultivation and differentiation because it participates in important functions such as the formation of the primitive intestine and vascular system and the primordial germ cells that migrate to the developing gonads. Macroscopically, the bovine yolk sac is a transparent membrane composed of three regions: one central and two ventrally elongated projections, similar to the letter Y [ 1 – 3 ].…”