Placentation in the rock cavy, Kerodon rupestris (Wied)
Introduction
The rock cavy, Kerodon rupestris (Wied), lives in the semi-arid caatinga of northeast Brazil. Its local name is the mocó. It belongs to the same family as the guinea pig (Caviidae), but although similar in size to the guinea pig, it differs in general appearance and way of life. Rock cavies are gregarious and crepuscular, passing the day in burrows under rocks or stones. They leave their shelters in the late afternoon or evening and run on the ground or climb trees looking for food, mainly tender leaves. They are especially partial to some species of creeper [1], [2].
The rock cavy is an extreme habitat specialist, having adapted to the near arid conditions of the caatinga [3], [4]. It is currently under threat due to destruction of this habitat as well as hunting. Elsewhere, efforts are underway to raise rock cavies under controlled conditions as a potential source of food [5]. It is therefore important to understand the reproductive biology of this species.
The placentae of hystricomorph rodents have a number of distinguishing features [6], [7], [8]. These include a varying amount of lobulation of the exchange area and the presence of a subplacenta. As in many rodents, an inverted yolk sac placenta is present until term. The present study was undertaken to describe the morphology of the rock cavy placenta at the light microscopical and ultrastructural level and to compare it with the placentae of other hystricomorph rodents [9].
Section snippets
Tissue collection
Placentae, fetal membranes and parts of the uteri were collected from 15 rock cavies bred in captivity at the Center for Breeding of Wild Animals, Mossoró. The research was authorized by the Brazilian Institute of the Environment and Renewable Natural Resources (IBAMA). The experimental protocol was approved by the Bioethics Committee of the School of Veterinary Medicine, University of Sao Paulo.
The animals were premedicated with midazolam (Dormine, Cristália, Itapira, S.P., Brazil; 1 mg/kg) and
Results
We obtained five placentae from early gestation, five from mid-gestation and seven from late gestation. There were two pairs of twins and 13 singleton pregnancies. Details of fetal and placental weight and size are given in Table 1. Maternal weight ranged from 0.7 to 1.0 kg. In late gestation, combined fetal and placental weights were 4.1% of maternal weight for singleton pregnancies and 10.9% for twin pregnancies.
Discussion
The overall plan of the rock cavy placenta resembles that of other hystricomorph rodents [6], [7], [8], [9]. It is highly lobed with a prominent subplacenta. The structure of hystricomorph placentae at the light microscopical level has been dealt with elsewhere [9], as has the vascular architecture of the placenta [10]. The present discussion focuses on the reproductive biology of the rock cavy; placental investments, which differ between species; and placental ultrastructure.
Acknowledgements
This study was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil. We are grateful for the skilled assistance of Antonio Almeida dos Santos, Caubi Rocha de Macedo and the kind support of Professor Idércio Luiz Sinhorini and Dr. Tatiana Carlesso dos Santos.
References (30)
- et al.
Placentation in the capybara (Hydrochaerus hydrochaeris), agouti (Dasyprocta aguti) and paca (Agouti paca)
Placenta
(2002) - et al.
Vascular organization of the hystricomorph placenta: a comparative study in the agouti, capybara, guinea pig, paca and rock cavy
Placenta
(2004) - et al.
Immunohistochemical identification of epithelial and mesenchymal cell types in the chorioallantoic and yolk sac placentae of the guinea-pig
Placenta
(1998) An electron microscopic study of the chorioallantoic placenta and the subplacenta of the cane rat (Thryonomys swinderianus Temminck)
Placenta
(1984)Ultrastructural evidence for transtrophoblastic channels in the hemomonochorial placenta of the degu (Octodon degus)
Placenta
(1992)- et al.
The ultrastructure of the trophoblastic layer of the degu (Octodon degus) placenta: a re-evaluation of the “channel problem”
Placenta
(1997) The role of coated vesicles in selective transfer across yolk sac epithelium
J Ultrastruct Res
(1982)Walker's mammals of the world
(1999)Plantas e animais para o nordeste
(1987)The comparative social behavior of Kerodon rupestris and Galea spixii and the evolution of behavior in the Caviidae
Bull Carnegie Mus Nat Hist
(1981)
Preservação e exploração de animais silvestres nativos: preá, cutia e mocó
Caatinga
Rates of growth in Kerodon rupestris and an assessment of its potential as a domesticated food source
Papéis Avulsos de Zoologia, Mus Zool Univ Sao Paulo
Development and phylogenetic significance of the fetal membranes and placenta of the African hystricognathous rodents Bathyergus and Hystrix
Am J Anat
Vertebrate fetal membranes: comparative ontogeny and morphology; evolution; phylogenetic significance; basic functions; research opportunities
Evolutionary transformations of chorioallantoic placental characters in rodentia with special reference to hystricognath species
J Exp Zool Part A Comp Exp Biol
Cited by (37)
Placentation and embryo death in the plains viscacha (Lagostomus maximus)
2021, PlacentaCitation Excerpt :In some species the decidua basalis forms a dense connective tissue structure called the capsule. This structural pattern for the caviomorph placenta has been described in numerous species such as Cavia porcellus (Guinea pig) [28,29], Kerodon rupestris (Rock cavy) [30]; Galea spixii (Spix's yellow-toothed cavy) [31]; Hydrochaeris hydrochaeris (capybara) [32] and Cuniculus paca (paca) [33], among other species. The umbilical cord of L. maximus included mostly two arteries and two veins.
Behavioural ecology in a predator-prey system
2018, Mammalian BiologyIFPA Senior Award Lecture: Mammalian fetal membranes
2016, PlacentaDoppler ultrasound of the placenta and maternal and fetal vessels during normal gestation in captive agoutis (Dasyprocta prymnolopha, Wagler, 1831)
2016, TheriogenologyCitation Excerpt :The subplacenta of agoutis is defined histologically as being formed by a single layer of cytotrophoblasts supported on a thin mesenchymal lamella [8,9]. Other authors report similar findings in other species of rodents, such as the guinea pig [25,32], lowland paca [7], and rock cavy [14]. The subplacental vascularization was mapped by the color Doppler examination of the umbilical artery.