Talk:Koala Development

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2009

Shoulder dysplasia in koalas (Phascolarctos cinereus) at San Diego Zoo

J Zoo Wildl Med. 2009 Sep;40(3):453-7.

Pye GW.

Zoological Society of San Diego, P.O. Box 120551, San Diego, California 92101, USA. gpye@sandiegozoo.org Abstract A radiographic study documented shoulder dysplasia (n = 43), with varying degrees of malformation of the supraglenoid and infraglenoid tubercles and the coracoid process, shallowing or loss of the glenoid cavity, flattening or loss of the humeral head, malformation of the greater and lesser tubercles, loss of the intertubercle groove, and humeral diaphyseal abnormalities, in northern koalas (Phascolarctos cinereus) in the San Diego Zoo (San Diego, California, USA) colony. Retrospectively, historic radiographs (n = 38) were examined where available. Prospectively, three standard views (lateral extended arm, ventrodorsal cranially positioned arms, and ventrodorsal caudally positioned arms) were imaged (n = 25). In all radiographs, shoulders were graded as normal, or mildly, moderately, or severely dysplastic. Although affected koalas typically do not exhibit clinical signs, degenerative joint disease may develop and clinical signs treated with nonsteroidal anti-inflammatory drugs. Where shoulder and hip radiographs were both available (n = 60), 92% of individuals had correlation between the degree of shoulder and hip dysplasia.

PMID: 19746859

2002

Gestational length in the koala, Phascolarctos cinereus

Anim Reprod Sci. 2002 Apr 15;70(3-4):261-6.

Gifford A, Fry G, Houlden BA, Fletcher TP, Deane EM.

Zoological Parks Board of New South Wales, P.O. Box 20, Mosman, NSW 2088, Australia. Abstract We report a possible case of extended gestation in the koala, Phascolarctos cinereus. Birth of a pouch young was first observed 127 days after the removal of the male from a multi-female colony at Taronga Zoo. No other males were present at that time or had access to the facility. Head measurements and other growth data collected at the time of detection and over the period of pouch life indicates the time from removal of the male and the date of birth to be between 50 and 77 days. DNA fingerprinting using microsatellite loci unambiguously assigned paternity of the pouch young to this male. These observations suggest either an extended period of gestation of at least 50 days, or activation of a dormant blastocyst from the previous breeding season, as the female entered the period of seasonal oestrus.

PMID: 11943495

Development of the male urogenital system of the koala phascolarctos cinereus

Anat Embryol (Berl). 1998 Mar;197(3):217-27.

Esson C, Armati PJ.

School of Biological Sciences, University of Sydney, NSW, Australia. Abstract This paper described several developmental stages of the male urogenital system in the koala Phascolarctos cinereus, employing both light and scanning electron microscopy. There are few studies of the development of the urogenital system in male marsupials. Findings by White and Timms (1994) that male koalas can be infected with Chlamydia psittaci emphasise the importance of studies on male animals and in particular their reproductive system. Specimens in our study ranged in age from 15 days postnatal to adults. Due to the rarity of such specimens, details of each specimen are linked to the changes of the structures at each available stage. Light microscopy revealed that differentiation of the gonads had commenced by 15 days postnatal and that the cytological arrangements of the urogenital system are essentially the same as those of other mammals. Scanning electron microscopy revealed stereocilia and microvilli along the lumen of each ductus epididymis and cilia and microvilli along the lumina of the vasa deferentia and urethra. The development of these structures coincided with the onset of sexual maturation, sperm production and differentiation at about three years of age.

PMID: 9543340

Other Marsupials

Developmental staging in a marsupial Dasyurus hallucatus

Anat Embryol (Berl). 1992;185(4):335-54.

Nelson JE.

Department of Ecology and Evolutionary Biology, Monash University, Clayton, Victoria, Australia. Abstract In a marsupial, Dasyurus hallucatus, pouch-young of various ages from newborn to 55 days were embedded in wax and serially sectioned. On the basis of the relative development of external and internal characteristics, they were placed in the Carnegie staging system developed by Streeter and elaborated by O'Rahilly and associates. Birth occurred at stage 15, and the end of embryogenesis (stage 23) was reached about day 33. Whereas stage 23 is characterised in all eutherians by the closure of the secondary palate, this occurs before stage 15 in D. hallucatus. Since most other characters of the newborn are at a stage 15 level of development, there has been a relative acceleration of development of the secondary palate (and forelimb) in D. hallucatus that allows it to suckle and breathe at the same time. Between D. hallucatus and eutherians, there is general agreement in the sequence of development and in the relative degree of most structures at each stage. Further marsupials should be examined to see if the minor differences noted are peculiar to D. hallucatus or apply to marsupials generally.

PMID: 1609962