1) In the early stages of the Trichosurus vulpecula embryos, there could be noted the D1, D2, and D3 pallial zones, and the basal zones B1, B2, B3, and B4. These pallial and basal telencephalic zones resemble those noted by Kuhlenbeck (1938) in the Tropidonatus natrix embryo; and also that in the chick embryo of 5 days and 16 hours.
2) At the 16 mm Perameles nasuta embryo and the 19 mm stage of Trichosurus vulpecula, the D2 pallial zone splits into three areas, namely the D2 am area, the D2 al area and the D (2+1)c pallial area. The D2 am zone becomes the parahippocampal cortex; the D2 al zone becomes the neocortex, and the D (2+1)c zone becomes the pyriform cortex. The D3 pallial zone in Trichosurus vulpecula gives rise to the hippocampus.
3) In Trichosurus vulpecula the lateral part of the nucleus epibasalis anterior or epistriatum becomes the claustrum. The claustrum is derived from the zone D1 and the basal zones B1 and B2. A doubling of the claustrum could be definitely noted at the 44 and 48 mm stages of Trichosurus vulpecula.
4) In Trichosurus vulpecula the medial part of the epistriatum or nucleus epibasalis anterior gives rise to the caudate nucleus and the putamen. They are both derived from the zones D1, B1, and B2. The nucleus epibasalis anterior is equivalent to the neostriatum of Kappers (1921).
5) At the 30 mm stage of Trichosurus vulpecula, the primordium of the globes pallidus could be noted. It is derived from an area of the dorsolateral part of the hypothalamic zone. The globus pallidus in mammals is a differentiation of the anterior entopeduncular nucleus. The anlage of the globus pallidus migrates rostrally; and at the 40 mm stage, it joins the putamen to become the mammalian form the globus pallidus.
6) The periamygdalar cortex, which becomes the amygdalar nucleus A; is derived from the basal zones B1, B2, and B3. The other amygdalar nuclei, namely the Gamma, Delta, and the Beta amygdalar nuclei are derived from the caudal parts of the fused zones D1+B1+B2. The amygdala is derived from the posterior part of the nucleus epibasalis.
7) The precommissural hippocampus could be first noted, at the precommissural telencephalic level at the 41 mm stage of Trichosurus vulpecula. It is well defined at the 44 and 48 mm stages.
8) In the 30 mm Trichosurus vulpecula embryo, the primordium of the cornu Ammonis could be noted, at the caudal telencephalic level. At the 44 and 48 mm Trichosurus vulpecula embryos the cornu Ammonis and dentate fascia began to resemble that form noted in the adult state.
抄録全体を表示