Expression of mRNAs encoding oestrogen receptor (ER) alpha and ERbeta, androgen receptor and progesterone receptor during gonadal and follicular development in the marsupial brushtail possum (Trichosurus vulpecula)
Reprod Fertil Dev. 2008;20(3):335-49.
Haydon LJ1, Juengel JL, Thomson BP, Eckery DC.
The objective of the present study was to determine which ovarian cells express mRNAs for oestrogen (ERalpha and ERbeta), androgen (AR) and progesterone (PR) receptors during ovarian and follicular development in the brushtail possum. Expression of ERalpha and/or ERbeta mRNA was observed from birth, initially in cells of the blastema, then in the medullary cords from Day 20. ERalpha was expressed in the oocytes and granulosa cells of secondary and antral follicles. Preovulatory follicles did not express ERalpha mRNA, although their oocytes were not examined for any gene. ERbeta mRNA was observed in oocytes at all follicular stages examined, but was not consistently observed in granulosa or theca cells. Expression of AR mRNA before Day 40 was very faint; thereafter, expression was observed in the medullary cords, peaking between Days 60 and 120. Oocytes, granulosa cells and theca of secondary and antral, but not preovulatory, follicles expressed AR mRNA. PR mRNA was expressed throughout the gonad by Day 20. Granulosa cells of some secondary and antral follicles and theca of antral follicles expressed PR mRNA. Thus, the expression of mRNAs encoding steroidogenic receptors in a time- and cell-specific manner supports a role for steroids in the process of ovarian follicular formation and growth. PMID: 18402753
Ontogenetic and phylogenetic transformations of the ear ossicles in marsupial mammals
J Morphol. 2002 Mar;251(3):219-38.
Sánchez-Villagra MR1, Gemballa S, Nummela S, Smith KK, Maier W.
This study is based on the examination of histological sections of specimens of different ages and of adult ossicles from macerated skulls representing a wide range of taxa and aims at addressing several issues concerning the evolution of the ear ossicles in marsupials. Three-dimensional reconstructions of the ear ossicles based on histological series were done for one or more stages of Monodelphis domestica, Caluromys philander, Sminthopsis virginiae, Trichosurus vulpecula, and Macropus rufogriseus. Several common trends were found. Portions of the ossicles that are phylogenetically older develop earlier than portions representing more recent evolutionary inventions (manubrium of the malleus, crus longum of the incus). The onset of endochondral ossification in the taxa in which this was examined followed the sequence; first malleus, then incus, and finally stapes. In M. domestica and C. philander at birth the yet precartilaginous ossicles form a supportive strut between the lower jaw and the braincase. The cartilage of Paauw develops relatively late in comparison with the ear ossicles and in close association to the tendon of the stapedial muscle. A feeble artery traverses the stapedial foramen of the stapes in the youngest stages of M. domestica, C. philander, and Sminthopsis virginiae examined. Presence of a large stapedial foramen is reconstructed in the groundplan of the Didelphidae and of Marsupialia. The stapedial foramen is absent in all adult caenolestids, dasyurids, Myrmecobius, Notoryctes, peramelids, vombatids, and phascolarctids. Pouch young of Perameles sp. and Dasyurus viverrinus show a bicrurate stapes with a sizeable stapedial foramen. Some didelphids examined to date show a double insertion of the Tensor tympani muscle. Some differences exist between M. domestica and C. philander in adult ossicle form, including the relative length of the incudal crus breve and of the stapes. Several differences exist between the malleus of didelphids and that of some phalangeriforms, the latter showing a short neck, absence of the lamina, and a ventrally directed manubrium. Hearing starts in M. domestica at an age in which the external auditory meatus has not yet fully developed, the ossicles are not fully ossified, and the middle ear space is partially filled with loose mesenchyme. The ontogenetic changes in hearing abilities in M. domestica between postnatal days 30 and 40 may be at least partially related to changes in middle ear structures. Copyright 2002 Wiley-Liss, Inc. PMID 11835361
The Comparative Anatomy of the Koala (Phascolartos cinereus) and Vulpine Phalanger (Trichosurus vulpecula)
=The Development of the Thymus, Epithelial Bodies, and Thyroid in the Marsupialia. Part I.--Trichosurus vulpecula
Fraser, E.; Hill, J. Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character (1905-1934). 1915-08-02. 89 (610):97–99
The early development of the marsupialia, with special reference to the native cat (dasyurus viverrinus)
The Development of the Pancreas, the Pancreatic and Hepatic Ducts, in Trichosurus vulpecula
Philosophical Transactions of the Royal Society of London. Series B, Containing Papers of a Biological Character (1896-1934). 1918-01-01. 208:307–350