Histological study of the cloacal region and associated structures in the hedgehog tenrec Echinops telfairi

Riedelsheimer, Bernd; Unterberger, Pia; Künzle, Heinz; Welsch, Ulrich

doi:10.1016/j.mambio.2006.10.012

Cited by 3 publications

(2 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Tenrecs continue to be viewed in this light (Treat et al, ). They have a low encephalisation index (Mack et al, ; Stankowich & Stensrud, ), a cloaca (Riedelsheimer, Unterburger, Kuenzle, & Welsch, ) and highly variable body temperature (Treat et al, ). Internal testes comprise another plesiomorphic feature, and this character is shared with other members of the Afrotheria clade (Kleisner, Ivell, & Flegr, ).…”

Section: Discussionmentioning

confidence: 99%

Hans Bluntschli in Berne: Researching reproduction in hedgehog tenrecs (Afrosoricida, Tenrecidae)

Carter

2019

Journal of Morphology

View full text Add to dashboard Cite

The Swiss anatomist Hans Bluntschli is best known as a primatologist. Yet, his focus during his later years in Berne was on reproduction in Malagasy tenrecs. This research was done with two graduate students, Robert Goetz and Fritz Strauss; all three had been obliged to leave Germany after the National Socialists came to power. Unique features of reproduction in tenrecs included nonantral follicles, intrafollicular fertilization, eversion of the corpus luteum, and polyovulation. The fertilized egg formed a blastula that developed into a blastocyst; there was no morula stage. A false placental cushion developed in the endometrium opposite the implantation site. Placentation was complex and included development of a prominent haemophagous organ. These findings are discussed in relation to current concepts of mammalian phylogeny that place tenrecs and golden moles in the same order and as close relatives to elephant shrews and the aardvark. K E Y W O R D S blastula, history of science, nonantral follicles, placentation, polyovulation

show abstract

Section: Discussionmentioning

confidence: 99%

Hans Bluntschli in Berne: Researching reproduction in hedgehog tenrecs (Afrosoricida, Tenrecidae)

Carter

2019

Journal of Morphology

View full text Add to dashboard Cite

show abstract

“…In marsupials, a small diverticulum represents the last trace of the cloaca. It is fully reduced in most placental mammals (Riedelsheimer et al 2007), and the coprodaeum (cranial-most part of the ancestral cloaca) becomes the terminal part of the gut and opens into the anus ( Fig. 4.2 S).…”

Section: Reproduction and Related Organsmentioning

confidence: 99%

4. Mammalian embryology and organogenesis

Werneburg¹,

Spiekman²,

Zachos³

et al. 2018

Mammalian Evolution, Diversity and Systematics

View full text Add to dashboard Cite

4.1 Historical introduction : The origin of the human being is one of the major philosophical questions. One way of answering it is through an ontogenetic and evolutionary approach. Theories about the developmental origin in the mother's womb were first documented by Greek scholars in the 5th century BC (Breidbach 2015). Being dependent on the success of reproduction, fertility has triggered human thinking for a much longer period of human evolution as is documented in the art of the Paleolithic, the Mesolithic, the Neolithic, and later phases of human cultural evolution (Fig. 4.1). Fertility was manifested by the representation of stout mother goddesses with a demonstrative focus on their hips and breasts (Fig. 4.1 C) and by the presentation of erect penises in men (Fig. 4.1 G). In some cases, the process of birth was depicted as a key event of life (Fig. 4.1 D). Birth, pregnancy, and lactation of other vertebrate species were also of interest to ancient cultures and were illustrated, particularly, among species that played an important role in everyday life, such as prey and domesticated, mostly mammalian, animals (Fig. 4.1 A and I). Fertility rites, including hierogamy (Fig. 4.1 H) and sodomy (Fig. 4.1 J), are thought to have played a major role in prehistoric cults and were meant to increase the number of offspring and to guarantee their health (Frazer 1922, Campbell 1960). These attempts to understand and to influence our own development culminated in the artificial representation of homunculi in the Renaissance age, in which a human was "created" by alchemists in a jar. The mental construct of a test-tube baby (Fig. 4.1 K) was a symbol for the development of the human mind itself, which alchemists tried to raise to a higher level of cognition (Gebelein 1996, Wiesing 2004). The historical representation of homunculi also corresponds to the ideas of preformationists in the 17th century that the human being is fully present as a miniature in the male's sperm and only has to unfold to progress through embryological development to a fully formed human (Fig. 4.1 F; Hartsoeker 1694). With the rise of evolutionary thinking (Bell et al. 2010), a broad scientific discourse about the unique anatomy and development of mammalian species emerged. Mammalian embryology received particular attention in comparative anatomy and physiology because of its relevance in understanding our own biological history (Haeckel 1874,1877, Keibel 1906). Recent scientific approaches try to manipulate the early embryology of mammals, including man, to prevent diseases (Gilbert 2006) or to select for particular forms through domestication (Clutton-Brock 1999). Experimental biological studies mainly focus on model organisms that are easy to breed, have a large number of offspring, and have short reproductive cycles. For placental embryology, the house mouse Mus musculus is most often used (

show abstract

Loss of RXFP2 and INSL3 genes in Afrotheria shows that testicular descent is the ancestral condition in placental mammals

et al. 2018

View full text Add to dashboard Cite

Descent of testes from a position near the kidneys into the lower abdomen or into the scrotum is an important developmental process that occurs in all placental mammals, with the exception of five afrotherian lineages. Since soft-tissue structures like testes are not preserved in the fossil record and since key parts of the placental mammal phylogeny remain controversial, it has been debated whether testicular descent is the ancestral or derived condition in placental mammals. To resolve this debate, we used genomic data of 71 mammalian species and analyzed the evolution of two key genes (relaxin/insulin-like family peptide receptor 2 [RXFP2] and insulin-like 3 [INSL3]) that induce the development of the gubernaculum, the ligament that is crucial for testicular descent. We show that both RXFP2 and INSL3 are lost or nonfunctional exclusively in four afrotherians (tenrec, cape elephant shrew, cape golden mole, and manatee) that completely lack testicular descent. The presence of remnants of once functional orthologs of both genes in these afrotherian species shows that these gene losses happened after the split from the placental mammal ancestor. These “molecular vestiges” provide strong evidence that testicular descent is the ancestral condition, irrespective of persisting phylogenetic discrepancies. Furthermore, the absence of shared gene-inactivating mutations and our estimates that the loss of RXFP2 happened at different time points strongly suggest that testicular descent was lost independently in Afrotheria. Our results provide a molecular mechanism that explains the loss of testicular descent in afrotherians and, more generally, highlight how molecular vestiges can provide insights into the evolution of soft-tissue characters.

show abstract

Histological study of the cloacal region and associated structures in the hedgehog tenrec Echinops telfairi

Cited by 3 publications

References 15 publications

Hans Bluntschli in Berne: Researching reproduction in hedgehog tenrecs (Afrosoricida, Tenrecidae)

Hans Bluntschli in Berne: Researching reproduction in hedgehog tenrecs (Afrosoricida, Tenrecidae)

4. Mammalian embryology and organogenesis

Loss of RXFP2 and INSL3 genes in Afrotheria shows that testicular descent is the ancestral condition in placental mammals

Contact Info

Product

Resources

About