The materno-fetal interface in llama (Lama guanicoe glama)

Abstract

Samples from 9 llamas (28 through 36 weeks of gestation) were collected and fixed in 4% buffered paraformaldehyde (light microscopy) and in 2.5% buffered glutaraldehyde (transmission and scanning electron microscopy). The material was processed in paraplast and slides (5mm) were stained with HE, PAS, Masson-Trichrome, acid phosphatase and Perl's. The uteroferrin was immunolocalized. The results show that llama placenta is chorioallantoic, diffuse, folded and epitheliochorial, and the fetus is covered with an epidermal membrane. The trophoblast cells have variable morphology: cubic, rounded and triangular cells, with cytoplasm containing PAS-positive granules. Binucleated cells with large cytoplasm and rounded nuclei, as well as giant trophoblastic cells with multiple nuclei were also observed. Numerous blood vessels were observed beneath the cells of the uterine epithelium and around the chorionic subdivided branches. Glandular activity was shown by PAS, Perl's, and acid phosphatase positive reactions in the cytoplasm and glandular lumen, and by immunolocalization of the uteroferrin in the glandular epithelium. The uterine glands open in spaces formed by the areoles, which are filled by PAS-positive material. The llama fetus was covered by the epidermal membrane, composed of stratified epithelium, with up to seven layers of mono-, bi- or trinucleated cells. The high level of maternal and fetal vascularization surfaces indicates an intense exchange of substances across both surfaces. The metabolic activity shown in the uterine glands suggests an adaptation of the gestation to the high altitudes of the natural habitat of this species.

Uterine Epithelial Morphology and Progesterone Receptors in a Mifepristone‐treated Viviparous Lizard Pseudemoia entrecasteauxii (Squamata: Scincidae) During Gestation

“…4B-D, insert). These structures resemble absorptive plaques that have been previously observed in the viviparous skink genus Mabuya (Ramirez-Pinilla et al, 2006), as well as in llamas (Iturrizaga et al, 2007). This is the first reported observation of this structure in P. entrecasteauxii, and indicates a common structural and functional relationship with absorptive placques in both sauropsid and mammalian taxa.…”

Morphology and ultrastructure of the chorioallantoic placenta of the Iberian mole (Talpa occidentalis) with special reference to heterophagous areolas and the nature of interhaemal barrier

“…Remarkably, the uterine glands and areolas of T. occidentalis show the same histochemical characters as those of the llama, a species with epitheliochorial placentation (Iturrizaga et al. 2007).…”

Pathogens and the placental fortress

“…Some—but not all—animals with minimally invasive epitheliochorial placentas show only patchy or absent syncytialization (horse, pig, camelids) [6,50], though they evolved convergently from more invasive ancestors [51]. Thus, closer contact with maternal blood is coincident with robust syncytialization.…”