Placentation in the Hottentot Golden Mole, Amblysomus hottentotus (Afrosoricida: Chrysochloridae)

Abstract

a b s t r a c tThe placentation of the Hottentot golden mole (Amblysomus hottentotus) has been examined using light and electron microscopy and lectin histochemistry of nine specimens at both mid and late gestation. The placentae were lobulated towards the allantoic surface and the lobules contained roughly parallel arrays of labyrinthine structures converging on a central spongy zone. At mid gestation, the arrays were composed of an inner cellular and outer syncytial trophoblast layer, the inner layer enclosing scant connective tissue and fetal capillaries. Maternal blood spaces coursed through the outer trophoblast and were lined by trophoblastic microvilli; the blood spaces were narrow in mid gestation but enlarged near term, while the inner trophoblast layer became thinner and seemed to be syncytial. These features were confirmed by transmission electron microscopy. The microvillous surfaces and dispersed cytoplasmic particles were heavily glycosylated, as shown by lectin histochemistry, and exhibited changes with maturation, particularly a loss in N-acetyl glucosamine oligomers bound by Phytolacca americana lectin on the microvilli lining the maternal blood spaces and outer trophoblast particles. A substantial yolk sac was present both in mid and late gestation stages. It was clearly unattached to the uterus in the later stages. These morphological features are discussed in relation to the phylogenetic position of Amblysomus with respect to other members of Afrosoricida and Afrotheria.

Retroviral envelope syncytin capture in an ancestrally diverged mammalian clade for placentation in the primitive Afrotherian tenrecs

“…The hemophagous region of Potamogalinae also possesses an ST layer at the tip of fetal villi, where fetal cells are in contact with the maternal tissues (28). Interestingly, the placental structure of a representative species of the closest Tenrecidae outgroup, the A. hottentotus species belonging to the Chrysochloridae, also has been described, and the absence of an hemophagous region has been demonstrated in this species (36). Again, this absence would be consistent with our observation that syncytin-Ten1 could not be found in the two tested Chrysochloridae species.…”

Placental glycotype of the caviomorph rodent Lagostomus maximus and its evolution within Eutheria

“…The Parsimony method finds the ancestral character states that minimize the number of steps of character change given the known terminal character state distribution in a tree, while the Likelihood method finds the character state assignment for each node that maximizes the probability of arriving at the known character states in the terminal taxa (given the stochastic model of evolution), allowing the character states at all other nodes to vary in all possible ways (Maddison & Maddison 2021). Information on the character states studied of all the species included in the analysis was recovered from what was available in the bibliography (Bulmer & Peel, 1996; Díaz et al, 2017; Dorsch et al, 2019; Fernández et al, 2000, 2014; Fiorentino et al, 2018; Jones et al, 1995, 1997, 2007, 2009, 2014, 2016; Jones & Aplin, 2009; Munson et al, 1989; Sandoval et al, 2001; Stewart et al, 2000; Sgambati et al, 2002; Tatsuzuki et al, 2009) and from our observations in L. maximus . We used a tree based on the taxon‐rich and well‐resolved phylogeny of Placentalia (O'Leary et al, 2013) combined with a more comprehensively sampled phylogeny of Rodentia (Fabre et al, 2015).…”

“…A relevant feature related to the invasiveness of the trophoblast and its expulsion at birth is the glycotype, a specific expression of different glycosidic residues (Jones et al, 1997). The glycotype of placentas with different invasiveness degrees (Jones et al, 1995, 2000, 2002, 2004, 2007, 2009, 2014; Stewart et al, 2000) has been determined using lectin histochemistry. Its knowledge allows the understanding of variations in unusual pregnancy events, such as the physiological early embryonic death (Fiorentino et al, 2018; Díaz et al, 2017; Dorsch et al, 2019), and the phylogenetic relationships between clades (Jones et al, 2007; Klisch et al, 2010).…”