Development of the blood-forming tissues of the tammar wallaby Macropus eugenii

Abstract

The development of the haematopoietic tissues of the tammar wallaby Macropus eugenii follows a similar pattern to that observed in eutherian and other metatherian mammals. At birth, the liver appears to be the only site of haematopoiesis with significant numbers of neutrophils and stem cells present in the circulation. By Day 3, the spleen shows limited haematopoietic activity and by Day 12 contains areas of erythroid and myeloid cells. At two weeks after birth, the haematopoetic activity in the liver declines and small areas of haematopoiesis are apparent in the bone marrow. By the end of the first month, the bone marrow appears to be the major site of haematopoiesis.

A Histological Investigation of the Lymphoid and Immunohaematopoietic Tissues of the Adult Stripe-Faced Dunnart <i>(Sminthopsis macroura)</i>

“…This is similar to observations in the pouchless opossum, which had scanty white pulp with older animals lacking white pulp entirely [Bryant and Shrifrine, 1974]. In the tammar wallaby at 60 days the spleen contained mainly red pulp with a rise in white pulp as the animal aged [Basden et al, 1996].…”

“…During early life the marrow is red and filled with many haematopoietic cells but in adulthood the marrow recedes to the axial skeleton and is replaced by adipose tissue [Weiss, 1972]. This is also the case in the metatherian species studied to date, including the Virginian opossum [Block, 1964] and tammar wallaby [Basden et al, 1996]. It also appears to be the case in the stripe-faced dunnart, as a few haematopoietic cells remained within the bone marrow matrix and the majority of cells present were adipocytes.…”

“…Whilst the liver is the initial site of haematopoiesis in metatherians [Block, 1964;Yadav and Papadimitriou, 1969;Basden et al, 1996], the adult stripe-faced dunnart liver is similar in appearance to that of other adult mammalian species [Cutts et al, 1973] and lacks haematopoietic regions. Lipids were present in some of the adult stripe-faced dunnart livers.…”

“…In general, however, the histological appearance of the major lymphoid tissues resembles that seen in eutherians. This has been documented, to varying degrees, in the American polyprotodont opossums, Monodelphis domestica [Stone et al, 1996], Didelphis virginiana [Block, 1964] and Didelphis albiventris [Coutinho et al, 1990] and a number of Australian diprotodonts and polyprotodonts including the common antechinus, Antechinus stuartii and Antechinus swainsonii [Poskitt et al, 1984a-c], the tammar wallaby, Macropus eugenii [Basden et al, 1996], the quokka, Setonix brachyurus [Yadav et al, 1972a, b], the brushtail possum, Trichosurus vulpecula and the koala, Phascolarctos cinereus . Most recently the availability of species cross-reactive antibodies to lymphocyte-associated antigens has permitted a more specific analysis of the lymphocyte populations in the lymphoid tissues of D. albiventris [Coutinho et al, 1994], the koala, the brushtail possum and the ringtail possum, Pseudocheirus peregrinus , the northern brown bandicoot, Isoodon macrourus [Cisternas and Armati, 1999] and the eastern grey kangaroo (Macropus giganteus) [Old and Deane, 2001].…”

Possible antimicrobial compounds from the pouch of the koala,Phascolarctos cinereus

“…These documented strategies include pre and post natal transfer of maternal immunoglobulins, high levels of neutrophils in neonatal blood and lymphoid cells in early mammary gland secretions [4,5,6,7]. The possible secretion of antimicrobial substances by the marsupial pouch was first suggested nearly 30 yr ago [8].…”