Trophoblast cells of ruminant placentas—A minireview

Abstract

Understanding of ruminant placental structure and function is essential for veterinarians and researchers. The ruminant placenta is classified as cotyledonary and synepitheliochorial on the bases of its gross anatomical features and histological characteristics respectively. The richly vascularized embryonic chorioallantois is lined on its outer surface by cells of the trophectodermal epithelium. These cells which assume specialized functions are referred to as trophoblast cells. Two morphologically and functionally distinct cell types have been recognized in the trophectoderm of the placenta of ruminant animals. These are the mononucleate trophoblast cells and the binucleate trophoblast cells. The occurrence, morphological characteristics, and specialized functions of these trophoblast cells, in relation to conceptus nutrition and survival in utero are discussed in this review.

Specific expression patterns and cell distribution of ancient and modern PAG in bovine placenta during pregnancy

“…Mononucleate cells play a fundamental role in the maternal recognition of pregnancy via the secretion of interferon-t and in foetal nutrition via the absorption of uterine histotroph. Binucleate cells have been suspected as being involved in conceptus implantation and are essential to the maintenance of pregnancy via their endocrine function (Igwebuike 2006). Among the molecules produced by trophoblastic cells, the pregnancy-associated glycoprotein (PAG) multigenic family represents a set of proteins that is synthesized in the whole cellular layer (Zoli et al 1992, Xie et al 1994.…”

Desmosomes in the Uterine Epithelium of Noninvasive Skink Placentae

“…In species with hemochorial placentation, the junctional complex of the uterine epithelial cell barrier becomes compromised at the time of implantation, which allows the trophoblast cells to fuse, displace or invade between uterine epithelial cells Enders, 1967, 1975;Finn and Lawn 1968;Enders and Schlafke, 1971;Lee et al, 1995;Igwebuike, 2006). As a consequence of this intrusion, the junctional complex of the uterine epithelium, including the tight junction, adherens junction and desmosomes, is greatly affected (Enders and Schlafke, 1971;Schlafke and Enders, 1975).…”

Dinâmica populacional de células de placenta bovina a fresco e em cultivo

“…Parte da função e caracterização das células placentárias bovinas permanece controversa ou desconhecida e, além disso, várias dessas células sofrem alterações durante o progresso da gestação, razão pela qual seu monitoramento torna-se importante (IGWEBUIKE, 2005).…”

“…As membranas apicais dessas células mostram microvilos que interdigitam com os microvilos do endotélio uterino, formando a área de contato maternofetal (BJÖRKMAN et al, 1969;DENT, 1973;IGWEBUIKE, 2005 A citometria de fluxo facilita a coleta rápida de células em suspensão, permitindo a definição precisa de subpopulações celulares com base na presença e intensidade de uma combinação de marcadores fenotípicos (SHAPIRO, 1994). A possibilidade de analisar simultaneamente diversas características celulares e um grande número de eventos permite, por um lado, a avaliação concomitante de aspectos morfológicos, fenotípicos e funcionais e, por outro, confere significado estatístico mesmo em fenômenos raros que não são detectáveis por outras metodologias (GRINDEM, 1996).…”