Development of Lung, Kidney and Skin in the Brushtail Possum, <i>Trichosurus vulpecula</i>

Abstract

The thyroid gland is not present at birth in marsupials and thyroid function begins during the latter half of pouch life. The hormonal output of the thyroid gland is important for normal development. In this study the structure of the lung, kidney and skin of the developing possum was examined and the structural development of these three organs was described. The lung of the newborn brushtail possum was functional and continued to develop during pouch life, alveolar formation beginning at day 39 and concluding at day 113 postpartum. The mesonephric kidneys of the newborn possum degenerated and were replaced by the metanephric kidneys, the nephrogenic zone of the metanephric kidney being present from 35 to 96 days postpartum. No new nephrons were formed after day 96. After the completion of nephrogenesis, the kidney increases in size through glomerular and tubular growth. The sequence of steps in the development of the possum skin was identical to that observed in other marsupials. The epidermis of the possum was thickest at 60 µm on about day 28 postpartum and as development proceeded the epidermis gradually decreased in thickness. A sparse number of primordia of hair follicles were observed at day 10 and the possum had a good covering of hair by day 129 postpartum. Correlation between the development of the lung, kidney and skin with the previously published plasma thyroxine concentration in the young possum suggests that thyroxine from the mother and from the young is important in the development of these three organs.

Postnatal lung and metabolic development in two marsupial and four eutherian species

“…Lung development is characteristically slow in marsupials (Krause & Leeson, 1975; Gemmell, 1986; Buaboocha & Gemmell, 1997; Burri et al. 2003).…”

The lymphoid and immunohaematopoietic tissues of the embryonic brushtail possum (Trichosurus vulpecula)

“…Hughes and Hall (1984) described the prenatal brushtail possum lungs as having small blood vessels and cuboidal epithelium lining the developing bronchi. Buaboocha and Gemmell (1997) also described the brushtail possum lung and stated that it had squamous epithelium and surfactantsecreting cells. The lung sections in this study were similar.…”

Development of the lung of the brushtail possum, Trichosurus vulpecula

“…In some marsupial species, such as the American opossum (Krause & Leeson, 1973) and bandicoot (Gemmell, 1986), alveolar development coincides with the time at which the young first leave the pouch. Buaboocha & Gemmell (1997) recorded that alveolar formation began in the lung of the brushtail possum at 39 days, concluding at 113 days, and that the lung had an adult appearance at 129 days. Fletcher & Selwood (2000) found that pouch young of this species are permanently attached to the teat for 70 days, soon after which the teat is voluntarily released.…”

“…Those which have been published have placed emphasis on the postnatal development of alveoli. These include studies of the American opossum, Didelphis virginiana (Sorokin, 1962;Krause & Leeson, 1973, 1975Krause et al 1976), Australian eastern native cat, Dasyurus viverrinus (Hill & Hill, 1955), Australian northern native cat, Dasyurus hallucatus (Gemmell & Nelson, 1988), the red-necked wallaby, Macropus rufogriseus (Walker & Gemmell, 1983), the tammar wallaby, Macropus eugenii (Runciman et al 1996(Runciman et al , 1999, the marsupial bandicoot, Isoodon macrourus (Gemmell & Little, 1982;Gemmell, 1986), and the brushtail possum, Trichosurus vulpecula (Gemmell & Nelson (1988); Buaboocha & Gemmell, 1997). Only Krause & Leeson (1973, 1975 provide some information concerning the development of bronchi, and Tucker (1974) makes brief mention of the trachea and bronchi of the brushtail possum and koala ( Phascolarctos cinereus ).…”